Window(3) User Contributed Perl Documentation Window(3)NAMEPDL::Graphics::PGPLOT::Window - A OO interface to PGPLOT windows
SYNOPSIS
perldl> use PDL::Graphics::PGPLOT::Window
perldl> $win = pgwin(Device => '/xs');
perldl> $a = pdl [1..100]
perldl> $b = sqrt($a)
perldl> $win->line($b)
perldl> $win->hold()
perldl> $c = sin($a/10)*2 + 4
perldl> $win->line($c)
In the following documentation the commands are not shown in their OO
versions. This is for historical reasons and should not cause too much
trouble.
DESCRIPTION
This package offers a OO interface to the PGPLOT plotting package. This
is intended to replace the traditional interface in
PDL::Graphics::PGPLOT and contains interfaces to a large number of
PGPLOT routines. Below the usage examples for each function tend to be
given in the non-OO version for historical reasons. This will slowly be
changed, but in the meantime refer to the section on OO-interface below
to see how to convert the usage information below to OO usage (it is
totally trivial).
PDL::Graphics::PGPLOT::Window is an interface to the PGPLOT graphical
libraries. It currently supports PGPLOT-5.2 and PGPLOT-5.2-cd2. The
-cd2 version includes RGB output and anti-aliasing.
High-level plotting commands:
imag - Display an image (uses pgimag/pggray/pgrgbi as appropriate)
fits_imag - Display a FITS image in scientific coordinates
cont - Display image as contour map
fits_cont - Display a FITS image in scientific coordinates as a contour map
vect - Display 2 images as a vector field
fits_vect - Display 2 FITS images in sci. coordinates as a vector field
ctab - Load an image colour table
ctab_info - Get information about currently loaded colour table
line - Plot vector as connected points
tline - Plot a collection of vectors as lines
lines - Plot a polyline, multicolor vector [threadable]
points - Plot vector as points
tpoints - Plot a collection of vectors as points [threadable]
errb - Plot error bars
bin - Plot vector as histogram (e.g. bin(hist($data)) )
hi2d - Plot image as 2d histogram (not very good IMHO...)
tcircle - Plot vectors as circles [threadable]
label_axes - Print axis titles
legend - Create a legend with different texts, linestyles etc.
Low-level plotting commands:
arrow - Draw an arrow
poly - Draw a polygon
rectangle - Draw a rectangle
text - Write text in the plot area
cursor - Interactively read cursor positions.
circle - Draw a circle
ellipse - Draw an ellipse.
Device manipulation commands:
new - Construct a new output device
pgwin - Exported hook to new()
close - Close a PGPLOT output device.
hold - Hold current plot window range - allows overlays etc.
release - Release back to freshly autoscaling for each command.
held - Indicates whether the current window is held.
focus - Set focus to the given device.
erase - Erase the current window (or panel).
options - Get the options set for the present output device.
id - The ID for the device.
device - The device type.
name - The window name.
Notes: $transform for image/cont etc. is used in the same way as the
"TR()" array in the underlying PGPLOT FORTRAN routine but is,
fortunately, zero-offset. The transform() routine can be used to create
this piddle.
For completeness: The transformation array connect the pixel index to a
world coordinate such that:
X = tr[0] + tr[1]*i + tr[2]*j
Y = tr[3] + tr[4]*i + tr[5]*j
Variable passing and extensions
In general variables are passed to the pgplot routines by using
"get_dataref" to get the reference to the values. Before passing to
pgplot routines however, the data are checked to see if they are in
accordance with the format (typically dimensionality) required by the
PGPLOT routines. This is done using the routine "checkarg" (internal
to PGPLOT). This routine checks the dimensionality of the input data.
If there are superfluous dimensions of size 1 they will be trimmed away
until the dimensionality is correct. Example:
Assume a piddle with dimensions (1,100,1,1) is passed to "line", which
expects its inputs to be vectors. "checkarg" will then return a piddle
with dimensions (100). If instead the same piddle was passed to "imag",
which requires 2D piddles as output, "checkarg" would return a piddle
with dimensionality (100, 1) (Dimensions are removed from the start)
Thus, if you want to provide support for another PGPLOT function, the
structure currently look like this (there are plans to use the Options
package to simplify the options parsing):
# Extract the hash(es) on the commandline
($arg, $opt)=_extract_hash(@_);
<Check the number of input parameters>
<deal with $arg>
checkarg($x, 3); # For a hypothetical 3D routine.
&catch_signals;
...
pgcube($n, $x->get_dataref);
&release_signals;
1;
(the catch_signals/release_signals pair prevent problems with the perl-
PGPLOT interface if the user hits c-C during an operation).
Setting options
All routines in this package take a hash with options as an optional
input. This options hash can be used to set parameters for the
subsequent plotting without going via the PGPLOT commands.
This is implemented such that the plotting settings (such as line
width, line style etc.) are affected only for that plot, any global
changes made, say, with "pgslw()" are preserved. Some modifications
apply when using the OO interface, see below.
Alphabetical listing of standard options
The following options are always parsed. Whether they have any
importance depend on the routine invoked - e.g. line style is
irrelevant for "imag", or the "justify" option is irrelevant if the
display is on 'hold'. This is indicated in the help text for the
commands below.
The options are not case sensitive and will match for unique
substrings, but this is not encouraged as obscure options might
invalidate what you thought was a unique substring.
In the listing below examples are given of each option. The actual
option can then be used in a plot command by specifying it as an
argument to the function wanted (it can be placed anywhere in the
command list).
E.g:
$opt={COLOR=>2};
line $x, $y, $opt; # This will plot a line with red color
If you are plotting to a hardcopy device then a number of options use a
different name:
HardLW instead of LineWidth
HardCH instead of CharSize
HardFont instead of Font
HardAxisColour instead of AxisColour
HardColour instead of Colour
[although I'm not sure when HardColour is actually used]
align
If "pix" is set, then images and plots are not stretched to fill
the plot area. the "align" string tells how to align them within
the available area. 'L' and 'R' shove the plot against the left
and right edges, respectively; 'B' and 'T' shove the plot against
the bottom and top edges. The default is to center the image.
e.g. 'BL' puts the image on the bottom left corner, while 'CT'
centers the image horizontally while placing it at the top of the
available plot area. This defaults to 'BT' for non-justified
images, to 'CC' for justified images.
arrow
This options allows you to set the arrow shape, and optionally size
for arrows for the vect routine. The arrow shape is specified as a
hash with the key FS to set fill style, ANGLE to set the opening
angle of the arrow head, VENT to set how much of the arrow head is
cut out and SIZE to set the arrowsize.
The following
$opt = {ARROW => {FS=>1, ANGLE=>60, VENT=>0.3, SIZE=>5}};
will make a broad arrow of five times the normal size.
Alternatively the arrow can be specified as a set of numbers
corresponding to an extention to the syntax for pgsah. The
equivalent to the above is
$opt = {ARROW => pdl([1, 60, 0.3, 5})};
For the latter the arguments must be in the given order, and if any
are not given the default values of 1, 45, 0.3 and 1.0 respectively
will be used.
arrowsize
The arrowsize can be specified separately using this option to the
options hash. It is useful if an arrowstyle has been set up and one
wants to plot the same arrow with several sizes. Please note that
it is not possible to set arrowsize and character size in the same
call to a plotting function. This should not be a problem in most
cases.
$opt = {ARROWSIZE => 2.5};
axis
Set the axis value (see "env"). If you pass in a scalar you set
the axis for the whole plot. You can also pass in an array ref for
finer control of the axes.
If you set the option to a scalar value, you get one of a few
standard layouts. You can specify them by name or by number:
EMPTY (-2) draw no box, axes or labels
BOX (-1) draw box only
NORMAL (0) draw box and label it with coordinates
AXES (1) same as NORMAL, but also draw (X=0,Y=0) axes
GRID (2) same as AXES, but also draw grid lines
LOGX (10) draw box and label X-axis logarithmically
LOGY (20) draw box and label Y-axis logarithmically
LOGXY (30) draw box and label both axes logarithmically
When using logarithmic axes ("LOGX", "LOGY" and "LOGXY") you
normally need to log the data yourself, e.g.
line $x->log10, $y, {axis=>'LOGX'};
For your convenience you can put PDL::Graphics::PGPLOT into autolog
mode. In this mode a call to "line" or "points" will log the data
for you and you can pass in the unmodified data, e.g.
autolog(1); # enable automatic logarithm calculation
line $x, $y, {axis=>'LOGX'}; # automatically displays logged x data
You can use the function interface to enable autologging:
autolog(1);
or use it with a window reference (mode switching on a per window
basis)
$win->autolog(1);
"autolog" without arguments returns the current autolog setting
(0=off, 1=on).
If you set the "AXIS" option to an array ref, then you can specify
the box/axis options separately for the horizontal (ordinate; X
coordinate; 0th element) and vertical (abscissa; Y coordinate; 1st
element)) axes. Each element of the array ref should contain a
PGPLOT format string. Presence or absence of specific characters
flags particular options. For normal numeric labels, the options
are:
A : draw axis for this dimension.
B : draw bottom (X) or left (Y) edge of frame.
C : draw top (X) or right (Y) edge of frame.
G : draw Grid of vertical (X) or horizontal (Y) lines.
I : Invert ticks: draw them outside the plot rather than inside.
L : Label the axis Logarithmically.
P : Extend ("Project") major tick marks outside the box.
M : Numeric labels go in the alternate place above (X) or to the
right (Y) of the viewport.
N : Numeric labels go in the usual location below (X) or to the
left (Y) of the viewport
T : Draw major tick marks at the major coordinate interval.
S : Draw minor tick marks (subticks).
V : Orient numeric labels Vertically. Only applicable to Y.
(The default is to write them parallel to the axis.)
1 : Force decimal labelling, instead of automatic choice
2 : Force exponential labeling, instead of automatic.
If you don't specify any axis value at all, the default is
['BCNST','BCNST'] for plots and ['BCINST','BCINST'] for images.
(These list ref elements are handed on directly to the low-level
PGPLOT routines).
In addition, you can specify that your axis labels should be
printed as days, hours, minutes, and seconds (ideal for julian
dates and delta-t, or for angular quantities). You do that by
setting additional character flags on the affected axis:
X : Use HH MM SS.S time labeling rather than conventional numeric
labels. The ordinate is in secsonds. Hours roll over at 24.
Y : Like 'X' but the hour field runs past 24 if necessary.
Z : Like 'X' but with a days field too (only shown where nonzero).
H : Label the numbers with superscript d, h, m, and s symbols.
D : Label the numbers with superscript o, ', and '' symbols.
F : Omit first (lowest/leftmost) label; useful for tight layouts.
O : Omit leading zeroes in numbers under 10 (e.g. " 3h 3m 1.2s"
rather than "03h 03m 01.2s").
For example, to plot a numeric quantity versus Julian day of the
year in a standard boxed plot with tick marks, you can use
["BNCSTZHO","BCNST"].
border
Normally the limits are chosen so that the plot just fits; with
this option you can increase (or decrease) the limits by either a
relative (ie a fraction of the original axis width) or an absolute
amount. Either specify a hash array, where the keys are "TYPE"
(set to 'relative' or 'absolute') and "VALUE" (the amount to change
the limits by), or set to 1, which is equivalent to
BORDER => { TYPE => 'rel', VALUE => 0.05 }
charsize
Set the character/symbol size as a multiple of the standard size.
$opt = {CHARSIZE => 1.5}
The HardCH option should be used if you are plotting to a hardcopy
device.
colour (or color)
Set the colour to be used for the subsequent plotting. This can be
specified as a number, and the most used colours can also be
specified with name, according to the following table (note that
this only works for the default colour map):
0 - WHITE 1 - BLACK 2 - RED 3 - GREEN 4 - BLUE
5 - CYAN 6 - MAGENTA 7 - YELLOW 8 - ORANGE 14 - DARKGRAY
16 - LIGHTGRAY
However there is a much more flexible mechanism to deal with
colour. The colour can be set as a 3 or 4 element anonymous array
(or piddle) which gives the RGB colours. If the array has four
elements the first element is taken to be the colour index to
change. For normal work you might want to simply use a 3 element
array with R, G and B values and let the package deal with the
details. The R,G and B values go from 0 to 1.
In addition the package will also try to interpret non-recognised
colour names using the default X11 lookup table, normally using the
"rgb.txt" that came with PGPLOT.
For more details on the handling of colour it is best that the user
consults the PGPLOT documentation. Further details on the handling
of colour can be found in the documentation for the internal
routine "_set_colour".
The HardColour option should be used if you are plotting to a
hardcopy device [this may be untrue?].
diraxis
This sets the direction of the axes of a plot or image, when you
don't explitly set them with the XRange and YRange options. It's
particularly useful when you want (for example) to put long
wavelengths (larger numbers) on the left hand side of your plot, or
when you want to plot an image in (RA,dec) coordinates.
You can use either a scalar or a two-element perl array. If you
set it to 0 (the default) then PDL will guess which direction you
want to go. If you set it to a positive number, the axis will
always increase to the right. If you set it to a negative number,
the axis will always increase to the left.
For example, [0,0] is the default, which is usually right. [1,1]
tells PGPLOT to always increase the axis values up and to the
right. For a plot of intensity (y-axis) versus wavelength (x-axis)
you could say [-1,1].
This option is really only useful if you want to allow autoranging
but need to set the direction that the axis goes. If you use the
ranging options ("XRange" and "YRange"), you can change the
direction by changing the order of the maximum and minimum values.
That direction will override "DirAxis".
filltype
Set the fill type to be used by "poly", "circle", "ellipse", and
"rectangle" The fill can either be specified using numbers or name,
according to the following table, where the recognised name is
shown in capitals - it is case-insensitive, but the whole name must
be specified.
1 - SOLID
2 - OUTLINE
3 - HATCHED
4 - CROSS_HATCHED
$opt = {FILLTYPE => 'SOLID'};
(see below for an example of hatched fill)
font
Set the character font. This can either be specified as a number
following the PGPLOT numbering or name as follows (name in
capitals):
1 - NORMAL
2 - ROMAN
3 - ITALIC
4 - SCRIPT
(Note that in a string, the font can be changed using the escape
sequences "\fn", "\fr", "\fi" and "\fs" respectively)
$opt = {FONT => 'ROMAN'};
gives the same result as
$opt = {FONT => 2};
The HardFont option should be used if you are plotting to a
hardcopy device.
hatching
Set the hatching to be used if either fillstyle 3 or 4 is selected
(see above) The specification is similar to the one for specifying
arrows. The arguments for the hatching is either given using a
hash with the key ANGLE to set the angle that the hatch lines will
make with the horizontal, SEPARATION to set the spacing of the
hatch lines in units of 1% of "min(height, width)" of the view
surface, and PHASE to set the offset the hatching. Alternatively
this can be specified as a 1x3 piddle "$hatch=pdl[$angle, $sep,
$phase]".
$opt = {FILLTYPE => 'HATCHED',
HATCHING => {ANGLE=>30, SEPARATION=>4}};
Can also be specified as
$opt = {FILL=> 'HATCHED', HATCH => pdl [30,4,0.0]};
For another example of hatching, see "poly".
justify
If "justify" is set true, then the plot axes are shrunk to fit the
plot or image and it specifies the aspect ratio of pixel
coordinates in the plot or image. Setting justify=>1 will produce
a correct-aspect-ratio, shrink-wrapped image or plot; setting
justify=>0.5 will do the same thing but with a short and fat plot.
The difference between "justify" and "pix" is that "pix" does not
affect the shape of the axes themselves.
linestyle
Set the line style. This can either be specified as a number
following the PGPLOT numbering:
1 - SOLID line
2 - DASHED
3 - DOT-DASH-dot-dash
4 - DOTTED
5 - DASH-DOT-DOT-dot
or using name (as given in capitals above). Thus the following two
specifications both specify the line to be dotted:
$opt = {LINESTYLE => 4};
$varopt = {LINESTYLE => 'DOTTED'};
The names are not case sensitive, but the full name is required.
linewidth
Set the line width. It is specified as a integer multiple of 0.13
mm.
$opt = {LINEWIDTH => 10}; # A rather fat line
The HardLW option should be used if you are plotting to a hardcopy
device.
pitch
Sets the number of data pixels per inch on the output device. You
can set the "unit" (see below) to change this to any other PGPLOT
unit (millimeters, pixels, etc.). Pitch is device independent, so
an image should appear exactly the same size (e.g. "Pitch=>100" is
100 dpi) regardless of output device.
pix Sets the pixel aspect ratio height/width. The height is adjusted
to the correct ratio, while maintaining any otherwise-set pitch or
scale in the horizontal direction. Larger numbers yield tall,
skinny pixels; smaller numbers yield short, fat pixels.
scale
Sets the number of output display pixels per data pixel. You can
set the "unit" (see below) to change this to number of PGPLOT units
(inches, millimeters, etc.) per data pixel. "scale" is deprecated,
as it is not device-independent; but it does come in handy for
quick work on digital displays, where aliasing might otherwise
interfere with image interpretation. For example, "scale=>1"
displays images at their native resolution.
Panel
It is possible to define multiple plot ``panels'' with in a single
window (see the NXPanel and NYPanel options in the constructor).
You can explicitly set in which panel most plotting commands occur,
by passing either a scalar or an array ref into the "Panel" option.
There is also a panel method, but its use is deprecated because of
a wart with the PGPLOT interface.
plotting & imaging range
Explicitly set the plot range in x and y. X-range and Y-range are
set separately via the aptly named options "XRange" and "YRange".
If omitted PGPLOT selects appropriate defaults (minimum and maximum
of the data range in general). These options are ignored if the
window is on hold.
line $x, $y, {xr => [0,5]}; # y-range uses default
line $x, $y, {XRange => [0,5], YRange => [-1,3]}; # fully specified range
imag $im, {XRange => [30,50], YRange=>[-10,30]};
fits_imag $im, {XRange=>[-2,2], YRange=>[0,1]};
Imaging requires some thought if you don't want to lose a pixel off
the edge of the image. Pixels are value-centered (they are
centered on the coordinate whose value they represent), so the
appropriate range to plot the entirety of a 100x100 pixel image is
"[-0.5,99.5]" on each axis.
OBJECT-ORIENTED INTERFACE
This section will briefly describe how the
PDL::Graphics::PGPLOT::Window package can be used in an object-oriented
(OO) approach and what the advantages of this would be. We will start
with the latter
Multiple windows.
For the common user it is probably most interesting to use the OO
interface when handling several open devices at the same time. If
you have one variable for each plot device it is easier to
distribute commands to the right device at the right time. This is
the angle we will take in the rest of this description.
Coding and abstraction
At a more fundamental level it is desirable to approach a situation
where it is possible to have a generic plotting interface which
gives access to several plotting libraries, much as PGPLOT gives
access to different output devices. Thus in such a hypothetical
package one would say:
my $win1 = Graphics::new('PGPLOT', {Device => '/xs'});
my $win2 = Graphics::new('gnuplot', {Background => 'Gray'};
From a more practical point of of view such abstraction also comes
in handy when you write a large program package and you do not want
to import routines nilly-willy in which case an OO approach with
method calls is a lot cleaner.
The pgwin exported constructor, arguably, breaks this philosophy;
hopefully it will ``wither away'' when other compatible modules are
available.
Anyway, enough philosophizing, let us get down to Earth and give some
examples of the use of OO PGPLOT. As an example we will take Odd (which
happens to be a common Norwegian name) who is monitoring the birth of
rabbits in O'Fib-o-nachy's farm (alternatively he can of course be
monitoring processes or do something entirely different). Odd wants the
user to be able to monitor both the birth rates and accumulated number
of rabbits and the spatial distribution of the births. Since these are
logically different he chooses to have two windows open:
$rate_win = PDL::Graphics::PGPLOT::Window->new(Device => '/xw',
Aspect => 1, WindowWidth => 5, NXPanel => 2);
$area_win = PDL::Graphics::PGPLOT::Window->new(Device => '/xw',
Aspect => 1, WindowWidth => 5);
See the documentation for new below for a full overview of the options
you can pass to the constructor.
Next, Odd wants to create plotting areas for subsequent plots and maybe
show the expected theoretical trends
$rate_win->env(0, 10, 0, 1000, {XTitle => 'Days', YTitle => '#Rabbits'});
$rate_win->env(0, 10, 0, 100, {Xtitle=>'Days', Ytitle => 'Rabbits/day'});
$area_win->env(0, 1, 0, 1, {XTitle => 'Km', Ytitle => 'Km'});
# And theoretical prediction.
$rate_win->line(sequence(10), fibonacci(10), {Panel => [1, 1]});
That is basically it. The commands should automatically focus the
relevant window. Due to the limitations of PGPLOT this might however
lead you to plot in the wrong panel... The package tries to be smart
and do this correctly, but might get it wrong at times.
STATE and RECORDING
A new addition to the graphics interface is the ability to record plot
commands. This can be useful when you create a nice-looking plot on the
screen that you want to re-create on paper for instance. Or if you want
to redo it with slightly changed variables for instance. This is still
under development and views on the interface are welcome.
The functionality is somewhat detached from the plotting functions
described below so I will discuss them and their use here.
Recording is off by default. To turn it on when you create a new device
you can set the "Recording" option to true, or you can set the
$PDL::Graphics::PGPLOT::RECORDING variable to 1. I recommend doing the
latter in your ".perldlrc" file at least since you will often have use
for recording in the perldl script.
Use of recording
The recording is meant to help you recreate a plot with new data or to
a different device. The most typical situation is that you have created
a beautiful plot on screen and want to have a Postscript file with it.
In the dreary old world you needed to go back and execute all commands
manually, but with this wonderful new contraption, the recorder, you
can just replay your commands:
dev '/xs', {Recording => 1}
$x = sequence(10)
line $x, $x**2, {Linestyle => 'Dashed'}
$s = retrieve_state() # Get the current tape out of the recorder.
dev '/cps'
replay $s
This should result in a "pgplot.ps" file with a parabola drawn with a
dashed line. Note the command "retrieve_state" which retrieves the
current state of the recorder and return an object (of type
PDL::Graphics::State) that is used to replay commands later.
Controlling the recording
Like any self-respecting recorder you can turn the recorder on and off
using the "turn_on_recording" and "turn_off_recording" respectively.
Likewise you can clear the state using the "clear_state" command.
$w=PDL::Graphics::PGPLOT::Window->new(Device => '/xs');
$w->turn_on_recording;
$x=sequence(10); $y=$x*$x;
$w->line($x, $y);
$w->turn_off_recording;
$w->line($y, $x);
$w->turn_on_recording;
$w->line($x, $y*$x);
$state = $w->retrieve_state();
We can then replay $state and get a parabola and a cubic plot.
$w->replay($state);
Tips and Gotchas!
The data are stored in the state object as references to the real data.
This leads to one good and one potentially bad consequence:
The good is that you can create the plot and then subsequently redo the
same plot using a different set of data. This is best explained by an
example. Let us first create a simple gradient image and get a copy of
the recording:
$im = sequence(10,10)
imag $im
$s=retrieve_state
Now this was a rather dull plot, and in reality we wanted to show
an image using "rvals". Instead of re-creating the plot (which of
course here would be the simplest option) we just change $im:
$im -= sequence(10,10)
$im += rvals(10,10)
Now replay the commands
replay $s
And hey presto! A totally different plot. Note however the trickery
required to avoid losing reference to $im
This takes us immediately to the major problem with the recording
though. Memory leakage! Since the recording keeps references to the
data it can keep data from being freed (zero reference count) when you
expect it to be. For instance, in this example, we lose totally track
of the original $im variable, but since there is a reference to it in
the state it will not be freed
$im = sequence(1000,1000)
imag $im
$s = retrieve_state
$im = rvals(10,10)
Thus after the execution of these commands we still have a
reference to a 1000x1000 array which takes up a lot of memory...
The solution is to call "clear" on the state variable:
$s->clear()
(This is done automatically if the variable goes out of scope). I
forsee this problem to most acute when working on the "perldl"
command line, but since this is exactly where the recording is most
useful the best advice is just to be careful and call clear on
state variables.
If you are working with scripts and use large images for instance I
would instead recommend that you do not turn on recording unless
you need it.
FUNCTIONS
A more detailed listing of the functions and their usage follows. For
all functions we specify which options take effect and what other
options exist for the given function. The function descriptions below
are all given for the non-OO usage for historical reasons, but since
the conversion to an OO method is trivial there is no major need for
concern. Whenever you see a function example of the form
Usage: a_simple_function($x, $y, $z [, $opt]);
and you wish to use the OO version, just let your mind read the above
line as:
Usage: $win->a_simple_function($x, $y, $z [, $opt]);
where $win is a PDL::Graphics::PGPLOT::Window object. That is all.
Window control functions.
pgwin
Exported constructor for PGPLOT object/device/plot window.
Usage: pgwin($opt);
Usage: pgwin($option->$value,...);
Usage: pgwin($device);
Parameters are passed on to new() and can either be specified by hash
reference or as a list.
See the documentation fo PDL::Graphics::PGPLOT::Window::new for
details.
Because pgwin is a convenience function, you can specify the device by
passing in a single non-ref parameter. For even further convenience,
you can even omit the '/' in the device specifier, so these two lines
deliver the same result:
$a = pgwin(gif);
$a = new PDL::Graphics::PGPLOT::Window({Dev=>'/gif'});
new
Constructor for PGPLOT object/device/plot window.
Usage: PDL::Graphics::PGPLOT::Window->new($opt);
Usage: PDL::Graphics::PGPLOT::Window->new($option=>$value,...);
Options to new() can either be specified via a reference to a hash
$win = PDL::Graphics::PGPLOT::Window->new({Dev=>'/xserve',ny=>2});
or directly, as an array
# NOTE: no more {} !
$win = PDL::Graphics::PGPLOT::Window->new(Dev=>'/xserve',ny=>2);
The following lists the recognised options:
AspectRatio
The aspect ratio of the image, in the sense vertical/horizontal.
See the discussion on size setting.
Device
The type of device to use. The syntax of this is the one used by
PGPLOT.
Hold
Hold the plot window so that subsequent plots can plot over
existing plots. This can be adjusted with the "hold()" and
"release()" methods.
NXPanel
The number of panels in the X-direction
NYPanel
The number of panels in the Y-direction
Size
Yet another way to identify the plot window size -- this takes a
scalar or an array ref containing one, two, or three numbers. One
number gives you a square window. Two gives you a rectangular
window "(X,Y)". Three lets you specify the unit compactly (e.g.
"[<X>,<Y>,1]" for inches, "[<X>,<Y>,2]" for mm) but is deprecated
in favor of using the "Unit" option. See the discussion on size
setting.
Unit
The unit to use for size setting. PGPLOT accepts inch, mm, or
pixel. The default unit is inches for historical reasons, but you
can choose millimeters or (God forbid) pixels as well. String or
numeric specifications are OK (0=normalized, 1=inches, 2=mm,
3=pixels). Normalized units make no sense here and are not
accepted. Ideally someone will one day hook this into the CPAN
units parser so you can specify window size in rods or attoparsecs.
WindowName
The name to give to the window. No particular use is made of this
at present. It would be great if it was possible to change the
title of the window frame.
WindowWidth
The width of the window in inches (or the specified Unit). See the
discussion on size setting.
WindowXSize and WindowYSize
The width and height of the window in inches (or the specified
Unit). See the discussion on size setting.
An important point to note is that the default values of most options
can be specified by passing these to the constructor. All general
options (common to several functions) can be adjusted in such a way,
but function specific options can not be set in this way (this is a
design limitation which is unlikely to be changed).
Thus the following call will set up a window where the default axis
colour will be yellow and where plot lines normally have red colour and
dashed linestyle.
$win = PDL::Graphics::PGPLOT::Window->new(Device => '/xs',
AxisColour => 'Yellow', Colour => 'Red', LineStyle => 'Dashed');
Size setting: There are a gazillion ways to set window size, in keeping
with TIMTOWTDI. In general you can get away with passing any unique
combination of an "<X>" size, a "<Y>"size, and/or an aspect ratio. In
increasing order of precedence, the options are: ("Units",
"AspectRatio", "WindowWidth", "Window<X,Y>Size", "Size").
So if you specify an AspectRatio *and* an X and a Y coordinate, the
AspectRatio is ignored. Likewise, if you specify Units and a three-
component Size, the Units option is ignored in favor of the numeric
unit in the Size.
If you don't specify enough information to set the size of the window,
you get the default pane size and shape for that device.
close
Close a plot window
Usage: $win->close()
Close the current window. This does not necessarily mean that the
window is removed from your screen, but it does ensure that the device
is closed.
A message will be printed to STDOUT giving the name of the file created
if the plot was made to a hardcopy device and $PDL::verbose is true.
held
Check if a window is on hold
$is_held = $win->held();
Function to check whether the window is held or not.
hold
Hold the present window.
Usage: $win->hold()
Holds the present window so that subsequent plot commands overplots.
panel
Switch to a different panel
$win->panel(<num>);
Move to a different panel on the plotting surface. Note that you will
need to erase it manually if that is what you require.
This routine currently does something you probably don't want, and
hence is deprecated for most use: if you say
$win->panel(1);
$win->imag($image);
then $image will actually be displayed in panel 2. That's because the
main plotting routines such as line and imag all advance the panel when
necessary. Instead, it's better to use the Panel option within
plotting commands, if you want to set the panel explicitly.
release
Release a plot window.
$win->release()
Release a plot window so that subsequent plot commands move to the next
panel or erase the plot and create a new plot.
erase
Erase plot
$win->erase($opt);
Erase a plot area. This accepts the option "Panel" or alternatively a
number or array reference which makes it possible to specify the panel
to erase when working with several panels.
Plotting functions
env
Define a plot window, and put graphics on 'hold'
$win->env( $xmin, $xmax, $ymin, $ymax, [$justify, $axis] );
$win->env( $xmin, $xmax, $ymin, $ymax, [$options] );
$xmin, $xmax, $ymin, $ymax are the plot boundaries. $justify is a
boolean value (default is 0); if true the axes scales will be the same
(see "justify"). $axis describes how the axes should be drawn (see
"axis") and defaults to 0.
If the second form is used, $justify and $axis can be set in the
options hash, for example:
$win->env( 0, 100, 0, 50, {JUSTIFY => 1, AXIS => 'GRID',
CHARSIZE => 0.7} );
In addition the following options can also be set for "env":
PlotPosition
The position of the plot on the page relative to the view surface
in normalised coordinates as an anonymous array. The array should
contain the lower and upper X-limits and then the lower and upper
Y-limits. To place two plots above each other with no space between
them you could do
$win->env(0, 1, 0, 1, {PlotPosition => [0.1, 0.5, 0.1, 0.5]});
$win->env(5, 9, 0, 8, {PlotPosition => [0.1, 0.5, 0.5, 0.9]});
Axis, Justify, Border
See the description of general options for these options.
AxisColour
Set the colour of the coordinate axes.
XTitle, YTitle, Title, Font, CharSize
Axes titles and the font and size to print them.
label_axes
Label plot axes
$win->label_axes(<xtitle>, <ytitle>, <plot title>, $options);
Draw labels for each axis on a plot.
imag
Display an image (uses "pgimag()"/"pggray()" as appropriate)
$win->imag ( $image, [$min, $max, $transform], [$opt] )
NOTES
$transform for image/cont etc. is used in the same way as the "TR()"
array in the underlying PGPLOT FORTRAN routine but is, fortunately,
zero-offset. The transform() routine can be used to create this piddle.
If $image is two-dimensional, you get a grey or pseudocolor image using
the scalar values at each X,Y point. If $image is three-dimensional
and the third dimension has order 3, then it is treated as an RGB true-
color image via rgbi.
There are several options related to scaling. By default, the image is
scaled to fit the PGPLOT default viewport on the screen. Scaling,
aspect ratio preservation, and 1:1 pixel mapping are available. (1:1
pixel mapping is useful for avoiding display artifacts, but it's not
recommended for final output as it's not device-independent.)
Here's an additional complication: the "pixel" stuff refers not
(necessarily) to normal image pixels, but rather to transformed image
pixels. That is to say, if you feed in a transform matrix via the
"TRANSFORM" option, the "PIX", "SCALE", etc. options all refer to the
transformed coordinates and not physical image pixels. That is a Good
Thing because it, e.g., lets you specify plate scales of your output
plots directly! See fits_imag for an example application. If you do
not feed in a transform matrix, then the identity matrix is applied so
that the scaling options refer to original data pixels.
To draw a colour bar (or wedge), either use the "DrawWedge" option, or
the "draw_wedge()" routine (once the image has been drawn).
Options recognised:
ITF
the image transfer function applied to the pixel values. It may be
one of 'LINEAR', 'LOG', 'SQRT' (lower case is acceptable). It
defaults to 'LINEAR'.
MIN
Sets the minimum value to be used for calculation of the color-table
stretch.
MAX
Sets the maximum value for the same.
RANGE
A more compact way to specify MIN and MAX, as a list: you can say
"Range=>[0,10]" to scale the color table for brightness values
between 0 and 10 in the iamge data.
CRANGE
Image values between MIN and MAX are scaled to an interval in
normalized color domain space, on the interval [0,1], before lookup
in the window's color table. CRANGE lets you use only a part of the
color table by specifying your own range -- e.g. if you say
"CRange=>[0.25,0.75]" then only the middle half of the pseudocolor
space will be used. (See the writeup on ctab().)
TRANSFORM
The PGPLOT transform 'matrix' as a 6x1 vector for display
DrawWedge
set to 1 to draw a colour bar (default is 0)
Wedge
see the draw_wedge() routine
The following standard options influence this command:
AXIS, BORDER, JUSTIFY, SCALE, PIX, PITCH, ALIGN, XRANGE, YRANGE
To see an image with maximum size in the current window, but square
pixels, say:
$win->imag( $a, { PIX=>1 } );
An alternative approach is to try:
$win->imag( $a, { JUSTIFY=>1 } );
To see the same image, scaled 1:1 with device pixels, say:
$win->imag( $a, { SCALE=>1 } );
To see an image made on a device with 1:2 pixel aspect ratio, with
X pixels the same as original image pixels, say
$win->imag( $a, { PIX=>0.5, SCALE=>2 } );
To display an image at 100 dpi on any device, say:
$win->imag( $a, { PITCH=>100 } );
To display an image with 100 micron pixels, say:
$win->imag( $a, { PITCH=>10, UNIT=>'mm' } );
imag1
Display an image with correct aspect ratio
$win->imag1 ( $image, [$min, $max, $transform], [$opt] )
This is syntactic sugar for
$win->imag( { PIX=>1, ALIGN=>'CC' } );
rgbi
Display an RGB color image
The calling sequence is exactly like "imag", except that the input
image must have three dimensions: "N x M x 3". The last dimension is
the (R,G,B) color value. This routine requires pgplot 5.3devel or
later. Calling rgbi explicitly is not necessary, as calling image with
an appropriately dimensioned RGB triplet makes it fall through to rgbi.
fits_imag
Display a FITS image with correct axes
$win->fits_imag( image, [$min, $max], [$opt] );
NOTES
Titles:
Currently fits_imag also generates titles for you by default and
appends the FITS header scientific units if they're present. So if
you say
$pdl->hdr->{CTYPE1} = "Flamziness";
$pdl->hdr->{CUNIT1} = "milliBleems";
$win->fits_imag($pdl);
then you get an X title of "Flamziness (milliBleems)". But you can
(of course) override that by specifying the XTitle and YTitle
switches:
$win->fits_imag($pdl,{Xtitle=>"Arbitrary"});
will give you "Arbitrary" as an X axis title, regardless of what's
in the header.
Scaling and aspect ratio:
If CUNIT1 and CUNIT2 (or, if they're missing, CTYPE1 and CTYPE2)
agree, then the default pixel aspect ratio is 1 (in scientific
units, NOT in original pixels). If they don't agree (as for a
spectrum) then the default pixel aspect ratio is adjusted
automatically to match the plot viewport and other options you've
specified.
You can override the image scaling using the SCALE, PIX, or PITCH
options just as with the imag() method -- but those parameters refer
to the scientific coordinate system rather than to the pixel
coordinate system (e.g. "PITCH=>100" means "100 scientific units per
inch", and "SCALE=>1" means "1 scientific unit per device pixel".
See the imag() writeup for more info on these options.
The default value of the "ALIGN" option is 'CC' -- centering the
image both vertically and horizontally.
Axis direction:
By default, fits_imag tries to guess which direction your axes are
meant to go (left-to-right or right-to-left) using the CDELT
keywords: if "CDELn" is negative, then rather than reflecting the
image fits_imag will plot the X axis so that the highest values are
on the left.
This is the most convenient behavior for folks who use calibrated
(RA,DEC) images, but it is technically incorrect. To force the
direction, use the DirAxis option. Setting "DirAxis=>1"
(abbreviated "di=>1") will force the scientific axes to increase to
the right, reversing the image as necessary.
Color wedge:
By default fits_imag draws a color wedge on the right; you can
explicitly set the "DrawWedge" option to 0 to avoid this. Use the
"WTitle" option to set the wedge title.
Alternate WCS coordinates:
The default behaviour is to use the primary/default WCS information
in the FITS header (i.e. the "CRVAL1","CRPIX1",... keywords). The
Greisen et al. standard
(<http://fits.cv.nrao.edu/documents/wcs/wcs.html>) allows
alternative/additional mappings to be included in a header; these
are denoted by the letters "A" to "Z". If you know that your image
contains such a mapping then you can use the "WCS" option to select
the appropriate letter. For example, if you had read in a Chandra
image created by the CIAO software package then you can display the
image in the "physical" coordinate system by saying:
$win->fits_imag( $pdl, { wcs => 'p' } );
The identity transform is used if you select a mapping for which
there is no information in the header. Please note that this suport
is experimental and is not guaranteed to work correctly; please see
the documentation for the _FITS_tr routine for more information.
fits_rgbi
Display an RGB FITS image with correct axes
$win->fits_rgbi( image, [$min,$max], [$opt] );
Works exactly like fits_imag, but the image must be in (X,Y,RGB) form.
Only the first two axes of the FITS header are examined.
fits_cont
Draw contours of an image, labelling the axes using the WCS information
in the FITS header of the image.
$win->fits_cont( image, [$contours, $transform, $misval], [$opt] )
Does the same thing for the cont routine that fits_imag does for the
imag routins.
draw_wedge
Add a wedge (colour bar) to an image.
$win->draw_wedge( [$opt] )
Adds a wedge - shows the mapping between colour and value for a pixel -
to the current image. This can also be achieved by setting "DrawWedge"
to 1 when calling the "imag" routine.
The colour and font size are the same as used to draw the image axes
(although this will probably fail if you did it yourself). To control
the size and location of the wedge, use the "Wedge" option, giving it a
hash reference containing any of the following:
Side
Which side of the image to draw the wedge: can be one of 'B', 'L',
'T', or 'R'. Default is 'R'.
Displacement
How far from the egde of the image should the wedge be drawn, in
units of character size. To draw within the image use a negative
value. Default is 1.5.
Width
How wide should the wedge be, in units of character size. Default
is 2.
Label
A text label to be added to the wedge. If set, it is probably
worth increasing the "Width" value by about 1 to keep the text
readable. Default is ''. This is equivalent to the "WTitle"
option to imag, fits_imag, and similar methods.
ForeGround (synonym Fg)
The pixel value corresponding to the "maximum" colour. If "undef",
uses the value used by "imag" (recommended choice). Default is
"undef".
BackGround (synonym Bg)
The pixel value corresponding to the "minimum" colour. If "undef",
uses the value used by "imag" (recommended choice). Default is
"undef".
$a = rvals(50,50);
$win = PDL::Graphics::PGPLOT::Window->new();
$win->imag( $a, { Justify => 1, ITF => 'sqrt' } );
$win->draw_wedge( { Wedge => { Width => 4, Label => 'foo' } } );
# although the following might be more sensible
$win->imag( $a, { Justify => 1, ITF => 'sqrt', DrawWedge => 1,
Wedge => { Width => 4, Label => 'foo'} } );
ctab
Load an image colour table.
Usage:
ctab ( $name, [$contrast, $brightness] ) # Builtin col table
ctab ( $ctab, [$contrast, $brightness] ) # $ctab is Nx4 array
ctab ( $levels, $red, $green, $blue, [$contrast, $brightness] )
ctab ( '', $contrast, $brightness ) # use last color table
Note: See PDL::Graphics::LUT for access to a large number of colour
tables.
Notionally, all non-RGB images and vectors have their colors looked up
in the window's color table. Colors in images and such are scaled to a
normalized pseudocolor domain on the line segment [0,1]; the color
table is a piecewise linear function that maps this one-dimensional
scale to the three-dimensional normalized RGB color space [0,1]^3.
You can specify specific indexed colors by appropriate use of the
(levels,red,green,blue) syntax -- but that is deprecated, since the
actual available number of colors can change depending on the output
device. (Someone needs to write a specific hardware-dependent lookup
table interface).
See also imag for a description of how to use only part of the color
table for a particular image.
ctab_info
Return information about the currently loaded color table
autolog
Turn on automatic logarithmic scaling in "line" and "points"
Usage: autolog([0|1]);
Setting the argument to 1 turns on automatic log scaling and setting it
to zero turns it off again. The function can be used in both the object
oriented and standard interface. To learn more, see the documentation
for PDL::Graphics::PGPLOT::Window.
my $win = PDL::Graphics::PGPLOT::Window->new(dev=>'/xserve');
my $x=sequence(10);
my $y=$x*$x+1;
$win->autolog(1);
$win->line($x,$y, {Axis => 'LogY'});
line
Plot vector as connected points
If the 'MISSING' option is specified, those points in the $y vector
which are equal to the MISSING value are not plotted, but are skipped
over. This allows one to quickly draw multiple lines with one call to
"line", for example to draw coastlines for maps.
Usage: line ( [$x,] $y, [$opt] )
The following standard options influence this command:
AXIS, BORDER, COLO(U)R, LINESTYLE, LINEWIDTH, MISSING,
JUSTIFY, SCALE, PITCH, PIX, ALIGN
$x = sequence(10)/10.;
$y = sin($x)**2;
# Draw a red dot-dashed line
line $x, $y, {COLOR => 'RED', LINESTYLE=>3};
lines
Plot a list of vectors as discrete sets of connected points
This works much like line, but for discrete sets of connected points.
There are two ways to break lines: you can pass in x/y coordinates just
like in line, but with an additional "pen" piddle that indicates
whether the pen is up or down on the line segment following each point
(so you set it to zero at the end of each line segment you want to
draw); or you can pass in an array ref containing a list of single
polylines to draw.
Happily, there's extra meaning packed into the "pen" piddle: it
multiplies the COLO(U)R that you set, so if you feed in boolean values
you get what you expect -- but you can also feed in integer or
floating-point values to get multicolored lines.
Furthermore, the sign bit of "pen" can be used to draw hairline
segments: if "pen" is negative, then the segment is drawn as though it
were positive but with LineWidth and HardLW set to 1 (the minimum).
Equally happily, even if you are using the array ref mechanism to break
your polylines you can feed in an array ref of "pen" values to take
advantage of the color functionality or further dice your polylines.
Note that, unlike line, "lines" has no no specify-$y-only calling path.
That's because "lines" is intended more for line art than for plotting,
so you always have to specify both $x and $y.
Infinite or bad values are ignored -- that is to say, if your vector
contains a non-finite point, that point breaks the vector just as if
you set pen=0 for both that point and the point before it.
Usage: $w->( $x, $y, [$pen], [$opt] );
$w->( $xy, [$pen], [$opt] );
$w->( \@xvects, \@yvects, [\@pen], [$opt] );
$w->( \@xyvects, [\@pen], [$opt] );
The following standard options influence this command:
AXIS, BORDER, COLO(U)R, LINESTYLE, LINEWIDTH, MISSING,
JUSTIFY, SCALE, PITCH, PIX, ALIGN
CAVEAT:
Setting "pen" elements to 0 prevents drawing altogether, so you can't
use that to draw in the background color.
points
Plot vector as points
Usage: points ( [$x,] $y, [$symbol(s)], [$opt] )
Options recognised:
SYMBOL - Either a piddle with the same dimensions as $x, containing
the symbol associated to each point or a number specifying
the symbol to use for every point, or a name specifying the
symbol to use according to the following (recognised name in
capital letters):
0 - SQUARE 1 - DOT 2 - PLUS 3 - ASTERISK
4 - CIRCLE 5 - CROSS 7 - TRIANGLE 8 - EARTH
9 - SUN 11 - DIAMOND 12- STAR
PLOTLINE - If this is >0 a line will be drawn through the points.
The following standard options influence this command:
AXIS, BORDER, CHARSIZE, COLOUR, LINESTYLE, LINEWIDTH,
JUSTIFY, SCALE, PIX, PITCH, ALIGN
"SymbolSize" allows to adjust the symbol size, it defaults to CharSize.
The "ColorValues" option allows one to plot XYZ data with the Z axis
mapped to a color value. For example:
use PDL::Graphics::LUT;
ctab(lut_data('idl5')); # set up color palette to 'idl5'
points ($x, $y, {ColorValues => $z});
$y = sequence(10)**2+random(10);
# Plot blue stars with a solid line through:
points $y, {PLOTLINE => 1, COLOUR => BLUE, symbol => STAR}; # case insensitive
errb
Plot error bars (using "pgerrb()")
Usage:
errb ( $y, $yerrors, [$opt] )
errb ( $x, $y, $yerrors, [$opt] )
errb ( $x, $y, $xerrors, $yerrors, [$opt] )
errb ( $x, $y, $xloerr, $xhierr, $yloerr, $yhierr, [$opt])
Any of the error bar parameters may be "undef" to omit those error
bars.
Options recognised:
TERM - Length of terminals in multiples of the default length
SYMBOL - Plot the datapoints using the symbol value given, either
as name or number - see documentation for 'points'
The following standard options influence this command:
AXIS, BORDER, CHARSIZE, COLOUR, LINESTYLE, LINEWIDTH,
JUSTIFY, SCALE, PIX, PITCH, ALIGN
$y = sequence(10)**2+random(10);
$sigma=0.5*sqrt($y);
errb $y, $sigma, {COLOUR => RED, SYMBOL => 18};
# plot X bars only
errb( $x, $y, $xerrors, undef );
# plot negative going bars only
errb( $x, $y, $xloerr, undef, $yloerr, undef );
cont
Display image as contour map
Usage: cont ( $image, [$contours, $transform, $misval], [$opt] )
Notes: $transform for image/cont etc. is used in the same way as the
"TR()" array in the underlying PGPLOT FORTRAN routine but is,
fortunately, zero-offset. The transform() routine can be used to create
this piddle.
Options recognised:
CONTOURS - A piddle with the contour levels
FOLLOW - Follow the contour lines around (uses pgcont rather than
pgcons) If this is set >0 the chosen linestyle will be
ignored and solid line used for the positive contours
and dashed line for the negative contours.
LABELS - An array of strings with labels for each contour
LABELCOLOUR - The colour of labels if different from the draw colour
This will not interfere with the setting of draw colour
using the colour keyword.
MISSING - The value to ignore for contouring
NCONTOURS - The number of contours wanted for automatical creation,
overridden by CONTOURS
TRANSFORM - The pixel-to-world coordinate transform vector
The following standard options influence this command:
AXIS, BORDER, COLOUR, LINESTYLE, LINEWIDTH,
JUSTIFY, SCALE, PIX, PITCH, ALIGN
$x=sequence(10,10);
$ncont = 4;
$labels= ['COLD', 'COLDER', 'FREEZING', 'NORWAY']
# This will give four blue contour lines labelled in red.
cont $x, {NCONT => $ncont, LABELS => $labels, LABELCOLOR => RED,
COLOR => BLUE}
bin
Plot vector as histogram (e.g. "bin(hist($data))")
Usage: bin ( [$x,] $data )
Options recognised:
CENTRE - if true, the x values denote the centre of the bin
otherwise they give the lower-edge (in x) of the bin
CENTER - as CENTRE
The following standard options influence this command:
AXIS, BORDER, COLOUR, JUSTIFY, LINESTYLE, LINEWIDTH
hi2d
Plot image as 2d histogram (not very good IMHO...)
Usage: hi2d ( $image, [$x, $ioff, $bias], [$opt] )
Options recognised:
IOFFSET - The offset for each array slice. >0 slants to the right
<0 to the left.
BIAS - The bias to shift each array slice up by.
The following standard options influence this command:
AXIS, BORDER, JUSTIFY, SCALE, PIX, PITCH, ALIGN
Note that meddling with the "ioffset" and "bias" often will require you
to change the default plot range somewhat. It is also worth noting that
if you have TriD working you will probably be better off using mesh3d
or a similar command - see the PDL::Graphics::TriD module.
$r=sequence(100)/50-1.0;
$y=exp(-$r**2)*transpose(exp(-$r**2))
hi2d $y, {IOFF => 1.5, BIAS => 0.07};
arrow
Plot an arrow
Usage: arrow($x1, $y1, $x2, $y2, [, $opt]);
Plot an arrow from "$x1, $y1" to "$x2, $y2". The arrow shape can be set
using the option "Arrow". See the documentation for general options for
details about this option (and the example below):
Example:
arrow(0, 1, 1, 2, {Arrow => {FS => 1, Angle => 1, Vent => 0.3, Size => 5}});
which draws a broad, large arrow from (0, 1) to (1, 2).
rect
Draw a non-rotated rectangle
Usage: rect ( $x1, $x2, $y1, $y2 )
Options recognised:
The following standard options influence this command:
AXIS, BORDER, COLOUR, FILLTYPE, HATCHING, LINESTYLE, LINEWIDTH
JUSTIFY, SCALE, PIX, PITCH, ALIGN
poly
Draw a polygon
Usage: poly ( $x, $y )
Options recognised:
The following standard options influence this command:
AXIS, BORDER, COLOUR, FILLTYPE, HATCHING, LINESTYLE, LINEWIDTH
JUSTIFY, SCALE, PIX, PITCH, ALIGN
# Fill with hatching in two different colours
$x=sequence(10)/10;
# First fill with cyan hatching
poly $x, $x**2, {COLOR=>5, FILL=>3};
hold;
# Then do it over again with the hatching offset in phase:
poly $x, $x**2, {COLOR=>6, FILL=>3, HATCH=>{PHASE=>0.5}};
release;
circle
Plot a circle on the display using the fill setting.
Usage: circle($x, $y, $radius [, $opt]);
All arguments can alternatively be given in the options hash using the
following options:
XCenter and YCenter
The position of the center of the circle
Radius
The radius of the circle.
ellipse
Plot an ellipse, optionally using fill style.
Usage: ellipse($x, $y, $a, $b, $theta [, $opt]);
All arguments can alternatively be given in the options hash using the
following options:
MajorAxis
The major axis of the ellipse - this must be defined or $a must be
given.
MinorAxis
The minor axis, like A this is required.
Theta (synonym Angle)
The orientation of the ellipse - defaults to 0.0. This is given in
radians.
XCenter and YCenter
The coordinates of the center of the ellipse. These must be
specified or $x and $y must be given.
NPoints
The number of points used to draw the ellipse. This defaults to 100
and might need changing in the case of very large ellipses.
The routine also recognises the same standard options as accepted by
poly.
rectangle
Draw a rectangle.
Usage: rectangle($xcenter, $ycenter, $xside, $yside, [, $angle, $opt]);
This routine draws a rectangle with the chosen fill style. Internally
it calls poly which is somewhat slower than "pgrect" but which allows
for rotated rectangles as well. The routine recognises the same options
as "poly" and in addition the following:
XCenter and YCenter
The position of the center of the rectangle. XCentre and YCentre
are valid synonyms.
XSide and YSide
The length of the X and Y sides. If only one is specified the shape
is taken to be square with that as the side-length, alternatively
the user can set Side
Side
The length of the sides of the rectangle (in this case a square) -
syntactic sugar for setting XSide and YSide identical. This is
overridden by XSide or YSide if any of those are set.
Angle (synonym Theta)
The angle at which the rectangle is to be drawn. This defaults to
0.0 and is given in radians.
vect
Display 2 images as a vector field
Usage: vect ( $w, $a, $b, [$scale, $pos, $transform, $misval], { opt } );
$w->vect($a,$b,[$scale,$pos,$transform,$misval], { opt });
Notes: $transform for image/cont etc. is used in the same way as the
"TR()" array in the underlying PGPLOT FORTRAN routine but is,
fortunately, zero-offset. The transform() routine can be used to create
this piddle.
This routine will plot a vector field. $a is the horizontal component
and $b the vertical component. The scale factor converts between
vector length units and scientific positional units. You can set the
scale, position, etc. either by passing in parameters in the normal
parameter list or by passing in options.
Options recognised:
SCALE - Set the scale factor for vector lengths.
POS - Set the position of vectors.
<0 - vector head at coordinate
>0 - vector base at coordinate
=0 - vector centered on the coordinate
TRANSFORM - The pixel-to-world coordinate transform vector
MISSING - Elements with this value are ignored.
The following standard options influence this command:
ARROW, ARROWSIZE, AXIS, BORDER, CHARSIZE, COLOUR,
LINESTYLE, LINEWIDTH,
$a=rvals(11,11,{Centre=>[5,5]});
$b=rvals(11,11,{Centre=>[0,0]});
vect $a, $b, {COLOR=>YELLOW, ARROWSIZE=>0.5, LINESTYLE=>dashed};
fits_vect
Display a pair of 2-D piddles as vectors, with FITS header
interpretation
Usage: fits_vect ($a, $b, [$scale, $pos, $transform, $misval] )
"fits_vect" is to vect as fits_imag is to imag.
transform
Create transform array for contour and image plotting
$win->transform([$xdim,$ydim], $options);
(For information on coordinate transforms, try PDL::Transform.) This
function creates a transform array in the format required by the image
and contouring routines. You must call it with the dimensions of your
image as arguments or pass these as an anonymous hash - see the example
below.
Angle
The rotation angle of the transform, in radians. Positive numbers
rotate the image clockwise on the screen.
ImageDimensions
The dimensions of the image the transform is required for. The
dimensions should be passed as a reference to an array.
Pixinc
The increment in output coordinate per pixel.
ImageCenter (or ImageCentre)
The centre of the image as an anonymous array or as a scalar, in
scientific coordinates. In the latter case the x and y value for
the center will be set equal to this scalar. This is particularly
useful in the common case when the center is (0, 0). (ImageCenter
overrides RefPos if both are specified).
RefPos (or ReferencePosition)
If you wish to set a pixel other than the image centre to a given
value, use this option. It should be supplied with a reference to
an array containing 2 2-element array references, e.g.
RefPos => [ [ $xpix, $ypix ], [ $xplot, $yplot ] ]
This will label pixel "($xpix,$ypix)" as being at position
"($xplot,$yplot)". For example
RefPos => [ [100,74], [ 0, 0 ] ]
sets the scientific coordinate origin to be at the center of the
(100,74) pixel coordinate. The pixel coordinates are pixel-
centered, and start counting from 0 (as all good pixel coordinates
should).
Example:
$im = rvals(100, 100);
$w = PDL::Graphics::PGPLOT::Window->new(Device => '/xs');
$t = $w->transform(dims($im), {ImageCenter => 0, Pixinc => 5});
$w->imag($im, {Transform => $t});
tline
Threaded line plotting
$win->tline($x, $y, $options);
This is a threaded interface to "line". This is convenient if you have
a 2D array and want to plot out every line in one go. The routine will
apply any options you apply in a "reasonable" way. In the sense that it
will loop over the options wrapping over if there are less options than
lines.
Example:
$h={Colour => ['Red', '1', 4], Linestyle => ['Solid' ,'Dashed']};
$tx=zeroes(100,5)->xlinvals(-5,5);
$ty = $tx + $tx->yvals;
$win->tline($tx, $ty, $h);
tpoints
A threaded interface to points
Usage: tpoints($x, $y, $options);
This is a threaded interface to "points". This is convenient if you
have a 2D array and want to plot out every line in one go. The routine
will apply any options you apply in a "reasonable" way. In the sense
that it will loop over the options wrapping over if there are less
options than lines.
Example:
$h={Colour => ['Red', '1', 4], Linestyle => ['Solid' ,'Dashed']};
$tx=zeroes(100,5)->xlinvals(-5,5);
$ty = $tx + $tx->yvals;
tpoints($tx, $ty, $h);
tcircle
A threaded interface to circle
Usage: tcircle($x, $y, $r, $options);
This is a threaded interface to "circle". This is convenient if you
have a list of circle centers and radii and want to draw every circle
in one go. The routine will apply any options you apply in a
"reasonable" way, in the sense that it will loop over the options
wrapping over if there are less options than circles.
Example:
$x=sequence(5);
$y=random(5);
$r=sequence(5)/10 + 0.1;
$h={justify => 1,Color => ['red','green','blue'], filltype => ['solid','outline','hatched','cross_hatched']};
tcircle($x, $y, $r, $h);
Note that $x and $y must be the same size (>1D is OK, though
meaningless as far as "tcircle" is concerned). $r can be the same size
as $x OR a 1-element piddle OR a single perl scalar.
Text routines
text
Write text in a plot window at a specified position.
Usage: text ($text, $x, $y [, $opt])
Options recognised:
"ANGLE"
The angle in degrees between the baseline of the text and the
horisontal (increasing counter-clockwise). This defaults to 0.
"JUSTIFICATION"
The justification of the text relative to the position specified.
It defaults to 0.0 which gives left-justified text. A value of 0.5
gives centered text and a value of 1.0 gives right-justified text.
"XPos", "YPos", "Text"
These gives alternative ways to specify the text and position.
"BackgroundColour"
This sets the background colour for the text in case an opaque
background is desired. You can also use the synonyms "Bg" and
"BackgroundColor".
The following standard options influence this command:
COLOUR, CHARSIZE
line sequence(10), sequence(10)**2;
text 'A parabola', 3, 9, {Justification => 1, Angle=>atan2(6,1)};
legend
Add a legend to a plot
Usage: legend($text, $x, $y, [, $width], $opt]);
This function adds a legend to an existing plot. The action is
primarily controlled by information in the options hash, and the basic
idea is that $x and $y determines the upper left hand corner of the box
in which the legend goes. If the width is specified either as an
argument or as an option in the option hash this is used to determine
the optimal character size to fit the text into part of this width
(defaults to 0.5 - see the description of "TextFraction" below). The
rest of the width is filled out with either lines or symbols according
to the content of the "LineStyle", "Symbol", "Colour" and "LineWidth"
options.
The local options recognised are as follows:
"Text"
An anonymous array of annotations, can also be specified directly.
"XPos" and "YPos"
The X and Y position of the upper left-hand corner of the text.
"Width" and "Height"
The width and/or height of each line (including symbol/line). This
is used to determine the character size. If any of these are set to
'Automatic' the current character size will be used.
"TextFraction"
The text and the symbol/line is set inside a box. "TextFraction"
determines how much of this box should be devoted to text. This
defaults to 0.5. You can also use "Fraction" as a synonym to this.
"TextShift"
This option allows for fine control of the spacing between the text
and the start of the line/symbol. It is given in fractions of the
total width of the legend box. The default value is 0.1.
"VertSpace" or "VSpace"
By default the text lines are separated by one character height (in
the sense that if the separation were 0 then they would lie on top
of each other). The "VertSpace" option allows you to increase (or
decrease) this gap in units of the character height; a value of 0.5
would add half a character height to the gap between lines, and
-0.5 would remove the same distance. The default value is 0.
"BackgroundColour"
This sets the background colour for the text in case an opaque
background is desired. You can also use the synonyms "Bg" and
"BackgroundColor".
line $x, $y, {Color => 'Red', LineStyle => 'Solid'};
line $x2, $y2, {Color => 'Blue', 'LineStyle' => 'Dashed', LineWidth => 10};
legend ['A red line', 'A blue line'], 5, 5,
{LineStyle => ['Solid', 'Dashed'], Colour => ['Red', 'Blue']
LineWidth => [undef, 10]}; # undef gives default.
Cursor routines
cursor
Interactively read cursor positions.
Usage: ($x, $y, $ch, $xref, $yref) = cursor($opt)
This routine has no standard input parameters, but the type of cursor
can be set by setting the option "Type" as a key in the anonymous hash
$opt. The first three return values from the function are always
defined and gives the position selected by the user and the character
pressed.
Depending on the cursor type selected the last two arguments might also
be defined and these give a reference position. For instance if the
cursor is selected to be "Rectangle" then the reference position gives
one of the corners of the rectangle and $x and $y the diagonally
opposite one.
Options recognised:
XRef, YRef
The reference position to be used
Type
The type of cursor. This can be selected using a number between 0
and 7 as in PGPLOT, or alternatively you can specify these as,
"Default" (0), "RadialLine" (1), "Rectangle" (2),
"TwoHorizontalLines" (3), "TwoVerticalLines" (4), "HorizontalLine"
(5), "VerticalLine" (6) and "CrossHair" (7) respectively. The
default cursor is just the normal mouse cursor.
For the "RadialLine" you must specify the reference point, whereas
for the "Two(Vertical|Horizontal)Lines" cursor the X or Y reference
point, respectively, must be specified.
To select a region on a plot, use the rectangle cursor:
($x, $y, $ch, $xref, $yref) = cursor({Type => 'Rectangle'});
poly pdl($x, $xref, $xref, $x, $x), pdl($y, $y, $yref, $yref, $y);
To select a region of the X-axis:
($x1, $y1, $ch) = cursor({Type => 'VerticalLine'});
($x2, $y2, $ch) = cursor({Type => 'TwoVerticalLines', XRef => $x1});
Internal routines
signal_catcher, catch_signals, release_signals
To prevent pgplot from doing a fandango on core, we have to block
interrupts during PGPLOT calls. Specifically, INT needs to get caught.
These internal routines provide a mechanism for that.
You simply bracket any PGPLOT calls with &catch_signals above and
&release_signals below, and the signal_catcher will queue up any
signals (like INT -- the control-C interrupt) until the
&release_signals call.
Any exit path from your hot code must include &release_signals, or
interrupts could be deferred indefinitely (which would be a bug). This
includes calls to &barf -- even barfs from someone you called! So
avoid calling out of the local module if possible, and use
release_and_barf() instead of barf() from within this module.
Perl 5.6.1 interrupt handling has a bug that this code tickles --
sometimes the re-emitted signals vanish into hyperspace. Perl 5.8
seems NOT to have that problem.
_open_new_window
Open a new window. This sets the window ID, which is the one used when
accessing a window later using "pgslct". It also sets the window name
to something easily remembered if it has not been set before.
_setup_window
This routine sets up a new window with its shape and size. This is also
where the size options are actually parsed. These are then forgotten
(well, they are stored in $self->{Options}) and the corresponding
aspect ratio and window width is stored. See the discussion under
new() for the logic.
Finally the subpanels are set up using "pgsubp" and colours and
linewidth are adjusted according to whether we have a hardcopy device
or not.
_status
This routine checks PGPLOT's status for the window. It returns OPEN if
the window is open and CLOSED if it is closed. (Windows can be closed
but still exist).
_reopen
This functions reopens a window. Since this is an internal function it
does not have a lot of error-checking. Make sure the device is closed
before calling this routine.
There is an unfortunate problem which pops up viz. that the window name
cannot be changed at this point since we are offering that to the rest
of the world. That might be sensible, but it means that the window name
will not reflect the id of the window - use "id()" for that (this is
also why we do not call "open_new_window" )
_advance_panel
This routine advances one plot panel, updating the CurrentPanel as
well. If the advance will proceed past the page the page will be
erased. Also note that when you advance one panel the hold value will
be changed.
_check_move_or_erase
This routine is a utility routine which checks if we need to move
panel, and if so will do this. It also checks if it is necessary to
advance panels, and whether they need to be erased.
_thread_options
This function is a cludgy utility function that expands an options hash
to an array of hashes looping over options. This is mainly of use for
"threaded" interfaces to standard plotting routines.
options
Access the options used when originally opening the window. At the
moment this is not updated when the window is changed later.
id
Access the window ID that PGPLOT uses for the present window.
device
This function returns the device type of the present window.
name
Accessor to set and examine the name of a window.
focus
Set focus for subsequent PGPLOT commands to this window.
info
Get general information about the PGPLOT environment.
@ans = $self->info( @item );
The valid values of @item are as below, where case is not important:
VERSION - What PGPLOT version is in use.
STATE - The status of the output device, this is returns 'OPEN'.
if the device is open and 'CLOSED' otherwise.
USER - The username of the owner of the spawning program.
NOW - The current date and time in the format
'dd-MMM-yyyy hh:mm'. Most people are likely to use Perl
functions instead.
DEVICE * - The current PGPLOT device or file, see also device().
FILE * - The filename for the current device.
TYPE * - And the device type for the current device.
DEV/TYPE * - This combines DEVICE and TYPE in a form that can be used
as input to new.
HARDCOPY * - This is flag which is set to 'YES' if the current device is
a hardcopy device and 'NO' otherwise.
TERMINAL * - This flag is set to 'YES' if the current device is the
user's terminal and 'NO' otherwise.
CURSOR * - A flag ('YES' or 'NO') to inform whether the current device
has a cursor.
Those items marced with a "*" only return a valid answer if the window
is open. A question mark ("?") is returned if the item is not
recognised or the information is not available.
_extract_hash
This routine takes and array and returns the first hash reference found
as well as those elements that are not hashes. Note the latter point
because all other references to hashes in the array will be lost.
_parse_unit
Convert a unit string or number into a PGPLOT-certified length unit
specification, or return undef if it won't go.
_parse_options
This is a convenience routine for parsing a set of options. It returns
both the full set of options and those that the user has set.
_save_status
Saves the PGPLOT state so that changes to settings can be made and then
the present state restored by "_restore_status".
_restore_status
Restore the PGPLOT state. See "_save_status".
_checkarg
This routine checks and optionally alters the arguments given to it.
_set_colour
This is an internal routine that encapsulates all the nastiness of
setting colours depending on the different PGPLOT colour models
(although HLS is not supported).
The routine works in the following way:
· At initialisation of the plot device the work colour index is
set to 16. The work index is the index the routine will modify
unless the user has specified something else.
· The routine should be used after standard interpretation and
synonym matching has been used. So if the colour is given as
input is an integer that colour index is used.
· If the colour is a reference the routine checks whether it is
an "ARRAY" or a "PDL" reference. If it is not an error message
is given. If it is a "PDL" reference it will be converted to
an array ref.
· If the array has four elements the first element is interpreted
as the colour index to modify and this overrules the setting
for the work index used internally. Otherwise the work index is
used and incremented until the maximum number of colours for
the output device is reached (as indicated by "pgqcol"). Should
you wish to change that you need to read the PGPLOT
documentation - it is somewhat device dependent.
· When the array has been recognised the R,G and B colours of the
user-set index or work index is set using the "pgscr" command
and we are finished.
· If the input colour instead is a string we try to set the
colour using the PGPLOT routine "pgscrn" with no other error-
checking. This should be ok, as that routine returns a rather
sensible error-message.
_standard_options_parser
This internal routine is the default routine for parsing options. This
routine deals with a subset of options that most routines will accept.
_image_xyrange
Given a PGPLOT tr matrix and an image size, calculate the data world
coordinates over which the image ranges. This is used in imag and
cont. It keeps track of the required half-pixel offset to display
images properly -- eg feeding in no tr matrix at all, nx=20, and ny=20
will will return (-0.5,19.5,-0.5,19.5). It also checks the options
hash for XRange/YRange specifications and, if they are present, it
overrides the appropriate output with the exact ranges in those fields.
_FITS_tr
Given a FITS image, return the PGPLOT transformation matrix to convert
pixel coordinates to scientific coordinates. Used by fits_imag,
fits_rgbi, and fits_cont, but may come in handy for other methods.
my $tr = _FITS_tr( $win, $img );
my $tr = _FITS_tr( $win, $img, $opts );
The return value ($tr in the examples above) is the same as returned by
the transform() routine, with values set up to convert the pixel to
scientific coordinate values for the two-dimensional image $img. The
$opts argument is optional and should be a HASH reference; currently it
only understands one key (any others are ignored):
WCS => undef (default), "", or "A" to "Z"
Both the key name and value are case insensitive. If left as "undef" or
"" then the primary coordinate mapping from the header is used,
otherwise use the additional WCS mapping given by the appropriate
letter. We make no checks that the given mapping is available; the
routine falls back to the unit mapping if the specified system is not
available.
The WCS option has only been tested on images from the Chandra X-ray
satellite (<http://chandra.harvard.edu/>) created by the CIAO software
package (<http://cxc.harvard.edu/ciao/>), for which you should set "WCS
=> "P"" to use the "PHYSICAL" coordinate system.
See <http://fits.cv.nrao.edu/documents/wcs/wcs.html> for further
information on the Representation of World Coordinate Systems in FITS.
INTERNAL
The coding tries to follow reasonable standards, so that all functions
starting with an underscore should be considered as internal and should
not be called from outside the package. In addition most routines have
a set of options. These are encapsulated and are not accessible outside
the routine. This is to avoid collisions between different variables.
AUTHOR
Karl Glazebrook [kgb@aaoepp.aao.gov.au] modified by Jarle Brinchmann
(jarle@astro.ox.ac.uk) who is also responsible for the OO interface,
docs mangled by Tuomas J. Lukka (lukka@fas.harvard.edu) and Christian
Soeller (c.soeller@auckland.ac.nz). Further contributions and bugfixes
from Kaj Wiik, Doug Burke, Craig DeForest, and many others.
All rights reserved. There is no warranty. You are allowed to
redistribute this software / documentation under certain conditions.
For details, see the file COPYING in the PDL distribution. If this file
is separated from the PDL distribution, the copyright notice should be
included in the file.
POD ERRORS
Hey! The above document had some coding errors, which are explained
below:
Around line 1234:
Deleting unknown formatting code T<>
perl v5.10.0 2006-01-13 Window(3)
