1IDL(3) User Contributed Perl Documentation IDL(3)
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6 PDL::IO::IDL -- I/O of IDL Save Files
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9 PDL::IO::IDL allows you to read and write IDL(tm) data files.
10 Currently, only reading is implemented. Scalars, arrays, and
12 structures are all supported. Heap pointers, compiled code, and
13 objects are not supported. Of those three, only heap pointers are
14 likely to be supported in the future.
15 This code was not developed by RSI, makers of IDL.
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19 These things seem to work:
20 BYTE, SHORT, LONG, FLOAT, and DOUBLE numeric types and arrays
22 All of these types seem to work fine. The corresponding variable is
23 stored as a PDL in the hash element with the same name as the
24 original variable in the file. Arrays are byteswapped as needed and
25 are read in so that the dim list has the same indexing order within
26 PDL as it did within IDL.
27 STRINGs and arrays of STRINGs
29 String types are stored as Perl list refs, in the hash element with
30 the same name as the original variable in the file.
31 Structures
33 Structures are stored as hash refs. The elements of the hash may be
34 accessed as values within the hash.
35 Common blocks
37 Variables that are notated as being in a common block are read as
38 normal. Common-block names are collected in the special hash value
39 '+common', which contains a hash each keyword of which is the name
40 of a common block and each value of which is an array of variable
41 names.
42 These things are known to be not working and may one day be fixed:
44 COMPLEX numbers
46 These could be implemented as 2-arrays or as PDL::Complex values,
47 but aren't yet.
48 PTR types
50 These could be implemented as perl refs but currently aren't.
51 writing
53 Maybe one day -- but why bother writing a broken file format?
54 NetCDF is better.
55 These things are known to be not working and will probably never be
57 fixed
58 Compiled code
60 Decompiling IDL code is a violation of the IDL end-user license. To
61 implement this, someone who does not hold an IDL license would have
62 to reverse-engineer a set of .SAV files sent to that person by
63 someone else with an IDL license.
64 Objects
66 IDL objects contain compiled code.
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69 ridl
70 $x = ridl("foo.sav");
71 Read an IDL save file from a file.
73 Upon successful completion, $x is a hash ref containing all of the
75 variables that are present in the save file, indexed by original
76 variable name.
77 IDL identifiers are case insensitive; they're all converted to upper-
79 case in the hash that gets returned. This may be adjustable at a
80 future date. Furthermore, because IDL identifiers can't contain
81 special characters, some fields that start with '+' are used to store
82 metadata about the file itself.
83 Numeric arrays are stored as PDLs, structures are stored as hashes, and
85 string and structure arrays are stored as perl lists. Named structure
86 types don't exist in perl in the same way that they do in IDL, so named
87 structures are described in the 'structs' field of the global metadata.
88 Anonymous structures are treated as simple hashes. Named structures
89 are also simple hashes, but they also contain a field '+name' that
90 refers to the name of the structure type.
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93 THIS CODE IS PROVIDED WITH NO WARRANTY and may be distributed and/or
94 modified under the same terms as PDL itself.
95 This code is based on the analysis of the IDL save file format
97 published by Craig Markwardt in 2002.
98 IDL is a trademark of Research Systems Incorporated (RSI). The PDL
100 development team, and authors of this code, are not affiliated with
101 RSI.
102perl v5.34.0 2021-08-16 IDL(3)