7 PSPP-Perl - Perl extension to PSPP
15 PSPP-Perl provides an interface to the libraries used by pspp to read and
24 $PSPP::VERSION='0.7.1';
26 XSLoader::load('PSPP', $PSPP::VERSION);
29 PSPP::onBoot($PSPP::VERSION);
33 =head1 PROGRAMMER'S INTERFACE
35 The subroutines in this package return zero or unref on error.
36 When errors occur, a string describing the error is written
44 use constant { SYSMIS => -(POSIX::DBL_MAX),
45 PERL_EPOCH => 12219379200 # Number of seconds between
57 =head2 PSPP::Dict::new
59 Creates a new dictionary. This returned dictionary will be empty.
60 Returns undef on failure.
62 =head3 set_documents ($string)
64 Sets the documents (comments) to C<string>.
66 =head3 add_document ($string)
68 Appends C<string> to the documents.
70 =head3 clear_documents ()
72 Removes all documents.
74 =head3 set_weight ($var)
76 Sets the weighting variable to C<var>.
83 my $self = pxs_dict_new ();
84 bless ($self, $class);
92 Returns the C<idx>th variable from the dictionary.
93 Returns undef if C<idx> is greater than or equal to the number
94 of variables in the dictionary.
102 my $var = pxs_get_variable ($dict, $idx);
106 bless ($var, "PSPP::Var");
113 =head3 get_var_by_name ($name)
115 Returns the variable from the dictionary whose name is C<name>.
116 If there is no such variable, a null reference will be returned.
124 my $var = pxs_get_var_by_name ($dict, $name);
128 bless ($var, "PSPP::Var");
140 Contains constants used to denote variable format types.
141 The identifiers are the same as those used in pspp to denote formats.
142 For example C<PSPP::Fmt::F> defines floating point format, and
143 C<PSPP::Fmt::A> denotes string format.
147 # These must correspond to the values in src/data/format.h
193 =head3 new ($dict, $name, %input_fmt)
195 Creates and returns a new variable in the dictionary C<dict>. The
196 new variable will have the name C<name>.
197 The input format is set by the C<input_fmt> parameter
199 By default, the write and print formats are the same as the input format.
200 The write and print formats may be changed (See L</set_write_format>),
201 L</set_print_format>). The input format may not be changed after
202 the variable has been created.
203 If the variable cannot be created, undef is returned.
213 my $self = pxs_dict_create_var ($dict, $name, \%format);
216 bless ($self, $class);
223 =head3 set_label ($label)
225 Sets the variable label to C<label>.
232 =head3 set_write_format (%fmt)
234 Sets the write format to C<fmt>. <fmt> is a hash containing the keys:
240 A constant denoting the format type. See L</PSPP::Fmt>.
244 An integer denoting the number of decimal places for the format.
248 An integer denoting the number of width of the format.
252 On error the subroutine returns zero.
260 pxs_set_write_format ($var, \%format);
265 =head3 set_print_format (%fmt)
267 Sets the print format to C<fmt>.
268 On error the subroutine returns zero.
276 pxs_set_print_format ($var, \%format);
281 =head3 set_output_format (%fmt)
283 Sets the write and print formats to C<fmt>. This is the same as
284 calling set_write_format followed by set_print_format.
285 On error the subroutine returns zero.
290 sub set_output_format
294 pxs_set_output_format ($var, \%format);
299 =head3 clear_value_labels ()
301 Removes all value labels from the variable.
308 =head3 add_value_label ($key, $label)
310 Adds the value label C<label> to the variable for the value C<key>.
311 On error the subroutine returns zero.
313 =head3 add_value_labels (@array)
324 while ( @li = each %values )
326 if ( $var->add_value_label ($li[0], "$li[1]") )
337 =head3 set_value_labels ($key, $value)
339 C<Set_value_labels> is identical to calling L</clear_value_labels>
340 followed by L</add_value_labels>.
341 On error the subroutine returns zero.
349 $self->clear_value_labels () ;
350 $self->add_value_labels (%labels);
355 =head3 set_missing_values ($val1 [, $val2[, $val3] ])
357 Sets the missing values for the variable.
358 No more than three missing values may be specified.
360 =head3 get_attributes()
362 Returns a reference to a hash of the custom variable attributes.
363 Each value of the hash is a reference to an array containing the
368 Returns the name of the variable.
372 Returns the label of the variable or undef if there is no label.
374 =head3 get_value_labels ()
376 Returns a reference to a hash containing the value labels for the variable.
377 The hash is keyed by data values which correpond to the labels.
381 package PSPP::Sysfile;
387 =head3 new ($filename, $dict [,%opts])
389 Creates a new system file from the dictionary C<dict>. The file will
390 be written to the file called C<filename>.
391 C<opt>, if specified, is a hash containing optional parameters for the
392 system file. Currently, the only supported parameter is
393 C<compress>. If C<compress> is non zero, then the system file written
394 will be in the compressed format.
395 On error, undef is returned.
398 =head3 append_case (@case)
400 Appends a case to the system file.
401 C<Case> is an array of scalars, each of which are the values of
402 the variables in the dictionary corresponding to the system file.
403 The special value C<PSPP::SYSMIS> may be used to indicate that a value
405 If the array contains less elements than variables in the dictionary,
406 remaining values will be set to system missing.
413 my $filename = shift;
417 my $self = pxs_create_sysfile ($filename, $dict, $opts);
421 bless ($self, $class);
430 Closes the system file.
432 This subroutine closes the system file and flushes it to disk. No
433 further cases may be written once the file has been closed.
434 The system file will be automatically closed when it goes out of scope.
438 package PSPP::Reader;
449 my $filename = shift;
451 my $self = pxs_open_sysfile ($filename);
455 bless ($self, $class);
462 =head3 open ($filename)
464 Opens a system file for reading.
466 Open is used to read data from an existing system file.
467 It creates and returns a PSPP::Reader object which can be used to read
468 data and dictionary information from C<filename>.
476 my $dict = pxs_get_dict ($reader);
478 bless ($dict, "PSPP::Dict");
487 Returns the dictionary associated with the reader.
489 =head3 get_next_case ()
491 Retrieves the next case from the reader.
492 This method returns an array of scalars, each of which are the values of
493 the data in the system file.
494 The first call to C<get_next_case> after C<open> has been called retrieves
495 the first case in the system file. Each subsequent call retrieves the next
496 case. If there are no more cases to be read, the function returns undef.
498 If the case contains system missing values, these values are set to the
501 =head2 Miscellaneous subroutines
503 The following subroutines provide (hopefully) useful information about the
504 values retrieved from a reader.
506 =head3 PSPP::format_value ($value, $variable)
508 Returns a scalar containing a string representing C<value> formatted accoring
509 to the print format of C<variable>.
510 In the most common ussage, C<value> should be a value of C<variable>.
513 =head3 PSPP::value_is_missing ($value, $variable)
515 Returns non-zero if C<value> is either system missing, or if it matches the
516 user missing criteria for C<variable>.
526 John Darrington, E<lt>john@darrington.wattle.id.auE<gt>
528 =head1 COPYRIGHT AND LICENSE
530 Copyright (C) 2007, 2008, 2009 by Free Software Foundation
532 This program is free software: you can redistribute it and/or modify
533 it under the terms of the GNU General Public License as published by
534 the Free Software Foundation, either version 3 of the License, or
535 (at your option) any later version.
537 This program is distributed in the hope that it will be useful,
538 but WITHOUT ANY WARRANTY; without even the implied warranty of
539 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
540 GNU General Public License for more details.
542 You should have received a copy of the GNU General Public License
543 along with this program. If not, see <http://www.gnu.org/licenses/>.