7 PSPP - Perl extension to PSPP
15 PSPP:: provides an interface to the libraries used by pspp to create
24 do 'pspp-vers.pl' || die "No version set";
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 a variable from a dictionary.
100 my $var = pxs_get_variable ($dict, $idx);
104 bless ($var, "PSPP::Var");
116 Contains constants used to denote variable format types.
117 The identifiers are the same as those used in pspp to denote formats.
118 For example C<PSPP::Fmt::F> defines floating point format, and
119 C<PSPP::Fmt::A> denotes string format.
123 # These must correspond to the values in src/data/format.h
169 =head3 new ($dict, $name, %input_fmt)
171 Creates and returns a new variable in the dictionary C<dict>. The
172 new variable will have the name C<name>.
173 The input format is set by the C<input_fmt> parameter
175 By default, the write and print formats are the same as the input format.
176 The write and print formats may be changed (See L</set_write_format>),
177 L</set_print_format>). The input format may not be changed after
178 the variable has been created.
179 If the variable cannot be created, undef is returned.
189 my $self = pxs_dict_create_var ($dict, $name, \%format);
192 bless ($self, $class);
199 =head3 set_label ($label)
201 Sets the variable label to C<label>.
208 =head3 set_write_format (%fmt)
210 Sets the write format to C<fmt>. <fmt> is a hash containing the keys:
216 A constant denoting the format type. See L</PSPP::Fmt>.
220 An integer denoting the number of decimal places for the format.
224 An integer denoting the number of width of the format.
228 On error the subroutine returns zero.
236 pxs_set_write_format ($var, \%format);
241 =head3 set_print_format (%fmt)
243 Sets the print format to C<fmt>.
244 On error the subroutine returns zero.
252 pxs_set_print_format ($var, \%format);
257 =head3 set_output_format (%fmt)
259 Sets the write and print formats to C<fmt>. This is the same as
260 calling set_write_format followed by set_print_format.
261 On error the subroutine returns zero.
266 sub set_output_format
270 pxs_set_output_format ($var, \%format);
275 =head3 clear_value_labels ()
277 Removes all value labels from the variable.
284 =head3 add_value_label ($key, $label)
286 Adds the value label C<label> to the variable for the value C<key>.
287 On error the subroutine returns zero.
289 =head3 add_value_labels (@array)
300 while ( @li = each %values )
302 if ( $var->add_value_label ($li[0], "$li[1]") )
313 =head3 set_value_labels ($key, $value)
315 C<Set_value_labels> is identical to calling L</clear_value_labels>
316 followed by L</add_value_labels>.
317 On error the subroutine returns zero.
325 $self->clear_value_labels () ;
326 $self->add_value_labels (%labels);
331 =head3 set_missing_values ($val1 [, $val2[, $val3] ])
333 Sets the missing values for the variable.
334 No more than three missing values may be specified.
338 Returns the name of the variable.
342 Returns the label of the variable or undef if there is no label.
344 =head3 get_value_labels ()
346 Returns a reference to a hash containing the value labels for the variable.
347 The hash is keyed by data values which correpond to the labels.
351 package PSPP::Sysfile;
357 =head3 new ($filename, $dict [,%opts])
359 Creates a new system file from the dictionary C<dict>. The file will
360 be written to the file called C<filename>.
361 C<opt>, if specified, is a hash containing optional parameters for the
362 system file. Currently, the only supported parameter is
363 C<compress>. If C<compress> is non zero, then the system file written
364 will be in the compressed format.
365 On error, undef is returned.
368 =head3 append_case (@case)
370 Appends a case to the system file.
371 C<Case> is an array of scalars, each of which are the values of
372 the variables in the dictionary corresponding to the system file.
373 The special value C<PSPP::SYSMIS> may be used to indicate that a value
375 If the array contains less elements than variables in the dictionary,
376 remaining values will be set to system missing.
383 my $filename = shift;
387 my $self = pxs_create_sysfile ($filename, $dict, $opts);
391 bless ($self, $class);
400 Closes the system file.
402 This subroutine closes the system file and flushes it to disk. No
403 further cases may be written once the file has been closed.
404 The system file will be automatically closed when it goes out of scope.
408 package PSPP::Reader;
419 my $filename = shift;
421 my $self = pxs_open_sysfile ($filename);
425 bless ($self, $class);
432 =head3 open ($filename)
434 Opens a system file for reading.
436 Open is used to read data from an existing system file.
437 It creates and returns a PSPP::Reader object which can be used to read
438 data and dictionary information from <C>filename.
446 my $dict = pxs_get_dict ($reader);
448 bless ($dict, "PSPP::Dict");
457 Returns the dictionary associated with the reader.
459 =head3 get_next_case ()
461 Retrieves the next case from the reader.
462 This method returns an array of scalars, each of which are the values of
463 the data in the system file.
464 The first call to <C>get_next_case after <C>open has been called retrieves
465 the first case in the system file. Each subsequent call retrieves the next
466 case. If there are no more cases to be read, the function returns undef.
468 If the case contains system missing values, these values are set to the
471 =head2 Miscellaneous subroutines
473 The following subroutines provide (hopefully) useful information about the
474 values retrieved from a reader.
476 =head3 PSPP::format_value ($value, $variable)
478 Returns a scalar containing a string representing C<value> formatted accoring
479 to the print format of C<variable>.
480 In the most common ussage, C<value> should be a value of C<variable>.
483 =head3 PSPP::value_is_missing ($value, $variable)
485 Returns non-zero if C<value> is either system missing, or if it matches the
486 user missing criteria for C<variable>.
496 John Darrington, E<lt>john@darrington.wattle.id.auE<gt>
498 =head1 COPYRIGHT AND LICENSE
500 Copyright (C) 2007, 2008 by Free Software Foundation
502 This program is free software: you can redistribute it and/or modify
503 it under the terms of the GNU General Public License as published by
504 the Free Software Foundation, either version 3 of the License, or
505 (at your option) any later version.
507 This program is distributed in the hope that it will be useful,
508 but WITHOUT ANY WARRANTY; without even the implied warranty of
509 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
510 GNU General Public License for more details.
512 You should have received a copy of the GNU General Public License
513 along with this program. If not, see <http://www.gnu.org/licenses/>.