IDL(3) User Contributed Perl Documentation IDL(3)NAMEPDL::IO::IDL-- I/O of IDL Save Files
DESCRIPTIONPDL::IO::IDL allows you to read and write IDL(tm) data files.
Currently, only reading is implemented. Scalars, arrays, and
structures are all supported. Heap pointers, compiled code, and
objects are not supported. Of those three, only heap pointers are
likely to be supported in the future.
This code was not developed by RSI, makers of IDL.
NOTES
These things seem to work:
BYTE, SHORT, LONG, FLOAT, and DOUBLE numeric types and arrays
All of these types seem to work fine. The corresponding variable is
stored as a PDL in the hash element with the same name as the
original variable in the file. Arrays are byteswapped as needed and
are read in so that the dim list has the same indexing order within
PDL as it did within IDL.
STRINGs and arrays of STRINGs
String types are stored as Perl list refs, in the hash element with
the same name as the original variable in the file.
Structures
Structures are stored as hash refs. The elements of the hash may be
accessed as values within the hash.
Common blocks
Variables that are notated as being in a common block are read as
normal. Common-block names are collected in the special hash value
'+common', which contains a hash each keyword of which is the name
of a common block and each value of which is an array of variable
names.
These things are known to be not working and may one day be fixed:
COMPLEX numbers
These could be implemented as 2-arrays or as PDL::Complex values,
but aren't yet.
PTR types
These could be implemented as perl refs but currently aren't.
writing
Maybe one day -- but why bother writing a broken file format?
NetCDF is better.
These things are known to be not working and will probably never be
fixed
Compiled code
Decompiling IDL code is a violation of the IDL end-user license. To
implement this, someone who does not hold an IDL license would have
to reverse-engineer a set of .SAV files sent to that person by
someone else with an IDL license.
Objects
IDL objects contain compiled code.
FUNCTIONS
ridl
$a = ridl("foo.sav");
Read an IDL save file from a file.
Upon successful completion, $a is a hash ref containing all of the
variables that are present in the save file, indexed by original
variable name.
IDL identifiers are case insensitive; they're all converted to upper-
case in the hash that gets returned. This may be adjustable at a
future date. Furthermore, because IDL identifiers can't contain
special characters, some fields that start with '+' are used to store
metadata about the file itself.
Numeric arrays are stored as PDLs, structures are stored as hashes, and
string and structure arrays are stored as perl lists. Named structure
types don't exist in perl in the same way that they do in IDL, so named
structures are described in the 'structs' field of the global metadata.
Anonymous structures are treated as simple hashes. Named structures
are also simple hashes, but they also contain a field '+name' that
refers to the name of the structure type.
AUTHOR, LICENSE, NO WARRANTY
THIS CODE IS PROVIDED WITH NO WARRANTY and may be distributed and/or
modified under the same terms as PDL itself.
This code is based on the analysis of the IDL save file format
published by Craig Markwardt in 2002.
IDL is a trademark of Research Systems Incorporated (RSI). The PDL
development team, and authors of this code, are not affiliated with
RSI.
perl v5.18.1 2013-05-12 IDL(3)
