1Misc(3) User Contributed Perl Documentation Misc(3)
2
6 PDL::IO::Misc - misc IO routines for PDL
7
9 Some basic I/O functionality: FITS, tables, byte-swapping
10
12 use PDL::IO::Misc;
13
15 bswap2
16 Signature: (x(); )
17 Swaps pairs of bytes in argument x()
19 bswap2 does not process bad values. It will set the bad-value flag of
21 all output piddles if the flag is set for any of the input piddles.
22 bswap4
24 Signature: (x(); )
25 Swaps quads of bytes in argument x()
27 bswap4 does not process bad values. It will set the bad-value flag of
29 all output piddles if the flag is set for any of the input piddles.
30 bswap8
32 Signature: (x(); )
33 Swaps octets of bytes in argument x()
35 bswap8 does not process bad values. It will set the bad-value flag of
37 all output piddles if the flag is set for any of the input piddles.
38 rcols()
40 Read ASCII whitespaced cols from a file into piddles and perl arrays
41 (also see "rgrep()").
42 There are two calling conventions - the old version, where a pattern
44 can be specified after the filename/handle, and the new version where
45 options are given as as hash reference. This reference can be given as
46 either the second or last argument.
47 The default behaviour is to ignore lines beginning with a # character
49 and lines that only consist of whitespace. Options exist to only read
50 from lines that match, or do not match, supplied patterns, and to set
51 the types of the created piddles.
52 Can take file name or *HANDLE, and if no columns are specified, all are
54 assumed. For the allowed types, see "Datatype_conversions" in
55 PDL::Core.
56 Options:
58 EXCLUDE or IGNORE - ignore lines matching this pattern (default
60 '/^#/').
61 INCLUDE or KEEP - only use lines which match this pattern (default '').
63 LINES - which line numbers to use. Line numbers start at 0 and the
65 syntax is 'a:b:c' to use every c'th matching line between a and b
66 (default '').
67 DEFTYPE - default data type for stored data (if not specified, use the
69 type stored in $PDL::IO::Misc::deftype, which starts off as double).
70 TYPES - reference to an array of data types, one element for each
72 column to be read in. Any missing columns use the DEFTYPE value
73 (default []).
74 PERLCOLS - an array of column numbers which are to be read into perl
76 arrays rather than piddles. References to these arrays are returned
77 after the requested piddles (default undef).
78 Usage:
80 ($x,$y,...) = rcols( *HANDLE|"filename", { EXCLUDE => '/^!/' },
81 $col1, $col2, ... )
82 ($x,$y,...) = rcols( *HANDLE|"filename", $col1, $col2, ...,
83 { EXCLUDE => '/^!/' } )
84 ($x,$y,...) = rcols( *HANDLE|"filename", "/foo/", $col1, $col2, ... )
85 e.g.,
87 $x = PDL->rcols 'file1';
89 ($x,$y) = rcols *STDOUT;
90 # read in lines containing the string foo, where the first
92 # example also ignores lines that with a # character.
93 ($x,$y,$z) = rcols 'file2', 0,4,5, { INCLUDE => '/foo/' };
94 ($x,$y,$z) = rcols 'file2', 0,4,5,
95 { INCLUDE => '/foo/', EXCLUDE => '' };
96 # ignore the first 27 lines of the file, reading in as ushort's
98 ($x,$y) = rcols 'file3', { LINES => '27:-1', DEFTYPE => ushort };
99 ($x,$y) = rcols 'file3',
100 { LINES => '27:', TYPES => [ ushort, ushort ] };
101 # read in the first column as a perl array and the next two as piddles
103 ($x,$y,$name) = rcols 'file4', 1, 2, { PERLCOLS => [ 0 ] };
104 printf "Number of names read in = %d\n", 1 + $#$name;
105 Notes:
107 1. Quotes are required on patterns.
109 2. Columns are separated by whitespace by default, use
111 $PDL::IO::Misc::colsep to specify an alternate separator.
112 3. For PDL-2.003, the meaning of the 'c' value in the LINES option has
114 changed: it now only counts matching lines rather than all lines as in
115 previous versions of PDL.
116 4. LINES => '-1:0:3' may not work as you expect, since lines are
118 skipped when read in, then the whole array reversed.
119 wcols()
121 Write ASCII whitespaced cols into file from piddles efficiently.
122 If no columns are specified all are assumed. Will optionally only
124 process lines matching a pattern. Can take file name or *HANDLE, and
125 if no file/filehandle is given defaults to STDOUT.
126 Options:
128 HEADER - prints this string before the data. If the string is not
130 terminated by a newline, one is added (default '').
131 Usage: wcols $piddle1, $piddle2,..., *HANDLE|"outfile", [\%options];
133 e.g.,
135 wcols $x, $y+2, 'foo.dat';
137 wcols $x, $y+2, *STDERR;
138 wcols $x, $y+2, '|wc';
139 wcols $a,$b,$c; # Orthogonal version of 'print $a,$b,$c' :-)
140 wcols "%10.3f", $a,$b; # Formatted
142 wcols "%10.3f %10.5g", $a,$b; # Individual column formatting
143 wcols $a,$b, { HEADER => "# a b" };
145 Note: columns are separated by whitespace by default, use
147 $PDL::IO::Misc::colsep to specify an alternate separator.
148 swcols()
150 generate string list from "sprintf" format specifier and a list of
151 piddles
152 "swcols" takes an (optional) format specifier of the printf sort and a
154 list of 1d piddles as input. It returns a perl array (or array
155 reference if called in scalar context) where each element of the array
156 is the string generated by printing the corresponding element of the
157 piddle(s) using the format specified. If no format is specified it uses
158 the default print format.
159 Usage: @str = swcols format, pdl1,pdl2,pdl3,...;
161 or
162 $str = swcols format, pdl1,pdl2,pdl3,...;
163 rgrep()
165 Read columns into piddles using full regexp pattern matching.
166 Options:
168 UNDEFINED: This option determines what will be done for undefined
170 values. For instance when reading a comma-separated file of the type
171 "1,2,,4" where the ",," indicates a missing value.
172 The default value is to assign $PDL::undefval to undefined values, but
174 if "UNDEFINED" is set this is used instead. This would normally be set
175 to a number, but if it is set to "Bad" and PDL is compiled with
176 Badvalue support (see "" in PDL::Bad) then undefined values are set to
177 the appropriate badvalue and the column is marked as bad.
178 DEFTYPE: Sets the default type of the columns - see the documentation
180 for
181 "rcols()"
182 TYPES: A reference to a Perl array with types for each column - see
184 the documentation for "rcols()"
185 BUFFERSIZE: The number of lines to extend the piddle by. It might speed
187 up the reading a little bit by setting this to the number of lines in
188 the file, but in general "rasc()" is a better choice
189 Usage
191 ($x,$y,...) = rgrep(sub, *HANDLE|"filename")
193 e.g.
195 ($a,$b) = rgrep {/Foo (.*) Bar (.*) Mumble/} $file;
197 i.e. the vectors $a and $b get the progressive values of $1, $2 etc.
199 rdsa()
201 Read a FIGARO/NDF format file.
202 Requires non-PDL DSA module. Contact Frossie (frossie@jach.hawaii.edu)
204 Usage:
205 ([$xaxis],$data) = rdsa($file)
207 $a = rdsa 'file.sdf'
209 Not yet tested with PDL-1.9X versions
211 isbigendian()
213 Determine endianness of machine - returns 0 or 1 accordingly
214 rasc()
216 Simple function to slurp in ASCII numbers quite quickly, although error
217 handling is marginal (to nonexistent).
218 $pdl->rasc("filename"|FILEHANDLE [,$noElements]);
220 Where:
221 filename is the name of the ASCII file to read or
222 open file handle
223 $noElements is the optional number of elements in the file to read.
224 (If not present, all of the file will be read to fill up $pdl).
225 $pdl can be of type float or double for more precision.
226 # (test.num is an ascii file with 20 numbers. One number per line.)
228 $in = PDL->null;
229 $num = 20;
230 $in->rasc('test.num',20);
231 $imm = zeroes(float,20,2);
232 $imm->rasc('test.num');
233 rcube
235 Read list of files directly into a large data cube (for efficiency)
236 $cube = rcube \&reader_function, @files;
238 $cube = rcube \&rfits, glob("*.fits");
240 This IO function allows direct reading of files into a large data cube,
242 Obviously one could use cat() but this is more memory efficient.
243 The reading function (e.g. rfits, readfraw) (passed as a reference) and
245 files are the arguments.
246 The cube is created as the same X,Y dims and datatype as the first
248 image specified. The Z dim is simply the number of images.
249
251 Copyright (C) Karl Glazebrook 1997 and Craig DeForest 2001, 2003. All
252 rights reserved. There is no warranty. You are allowed to redistribute
253 this software / documentation under certain conditions. For details,
254 see the file COPYING in the PDL distribution. If this file is separated
255 from the PDL distribution, the copyright notice should be included in
256 the file.
257perl v5.12.3 2011-03-31 Misc(3)