docs

[pspp] / perl-module / Examples.pod

diff --git a/perl-module/Examples.pod b/perl-module/Examples.pod
index fc3f016777dee06431fbb53a9dfaac40f74a269b..eba537c81f51901d48b2b78ff1a41a8f1e77c96f 100644 (file)
--- a/perl-module/Examples.pod
+++ b/perl-module/Examples.pod
@@ -1,5 +1,21 @@
 =pod
 
+=for comment PSPP - a program for statistical analysis.
+=for comment Copyright (C) 2019 Free Software Foundation, Inc.
+=for comment
+=for comment This program is free software: you can redistribute it and/or modify
+=for comment it under the terms of the GNU General Public License as published by
+=for comment the Free Software Foundation, either version 3 of the License, or
+=for comment (at your option) any later version.
+=for comment
+=for comment This program is distributed in the hope that it will be useful,
+=for comment but WITHOUT ANY WARRANTY; without even the implied warranty of
+=for comment MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+=for comment GNU General Public License for more details.
+=for comment
+=for comment You should have received a copy of the GNU General Public License
+=for comment along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
 =head1 PSPP::Examples
 
 This page shows some simple examples of using the PSPP module.
@@ -7,7 +23,7 @@ See L<PSPP> for details on each of the subroutines.
 
 =head2 A Simple example
 
-This example creates a system file called F<foo.sav>, containing one 
+This example creates a system file called F<foo.sav>, containing one
 variable called "id".  It contains no data.
 
        use PSPP;
@@ -29,7 +45,7 @@ Their formats are F2.0, A80 and DATETIME17 respectively.
        my $dict = PSPP::Dict->new ();
        PSPP::Var->new ($dict, "id",
                   (fmt=>PSPP::Fmt::F, width=>2, decimals=>0) );
-       
+
        PSPP::Var->new ($dict, "name", (fmt=>PSPP::Fmt::A, width=>80) );
        PSPP::Var->new ($dict, "dob",  (fmt=>PSPP::Fmt::DATETIME) );
 
@@ -60,7 +76,7 @@ This example creates a file with 3 cases.
        use PSPP;
 
        my $dict = PSPP::Dict->new ();
-       PSPP::Var->new ($dict, "id", 
+       PSPP::Var->new ($dict, "id",
           (fmt=>PSPP::Fmt::F, width=>2, decimals=>0) );
 
        PSPP::Var->new ($dict, "name", (fmt=>PSPP::Fmt::A, width=>8) );
@@ -76,19 +92,19 @@ This example creates a file with 3 cases.
 =head2  Variables with differing input and output formats
 
 By default,  a variable's output format corresponds to the input format.
-However, the output format may be changed after the variable has 
+However, the output format may be changed after the variable has
 been created.
 
 This example shows how  to create a DATETIME variable using the current time
-as its value.  Since pspp uses a different epoch to perl, the constant 
-PSPP::PERL_EPOCH needs to be added to the value returned from time(), in order 
+as its value.  Since pspp uses a different epoch to perl, the constant
+PSPP::PERL_EPOCH needs to be added to the value returned from time(), in order
 that it be correctly represented by pspp.
 
        use PSPP;
 
        my $dict = PSPP::Dict->new ();
 
-       my $var1 = PSPP::Var->new ($dict, "entrytime", 
+       my $var1 = PSPP::Var->new ($dict, "entrytime",
                (fmt=>PSPP::Fmt::F) );
 
        $var1->set_output_format ( (fmt=>PSPP::Fmt::DATETIME, width=>20) );
@@ -97,9 +113,50 @@ that it be correctly represented by pspp.
 
        my $now = time ();
 
-       $sysfile->append_case ( [ $now  + PSPP::PERL_EPOCH]  ) 
+       $sysfile->append_case ( [ $now  + PSPP::PERL_EPOCH]  )
                || die "Cant write case";
-       
+
        $sysfile->close();
 
-=cut
\ No newline at end of file
+=head2  Reading data
+
+Data can be read from a system file or other source:
+
+       use PSPP;
+
+       my $sf = PSPP::Reader->open ("foo.sav");
+
+       my $dict = $sf->get_dict ();
+
+
+Once opened, the dictionary can be used like any other.
+
+       for ($v = 0 ; $v < $dict->get_var_cnt() ; $v++)
+       {
+           my $var = $dict->get_var ($v);
+
+           # Print the variables
+           my $name = $var->get_name ();
+           my $label = $var->get_label ();
+           print "Var: $name, Label: $label\n";
+
+           # Retrieve and print the value labels
+           my $vl = $var->get_value_labels ();
+           print "$_: $vl->{$_}\n" for keys %$vl;
+       }
+
+
+Reading of data must be done sequentially using the C<get_next_case> method.
+
+       while (my $c = $sf->get_next_case () )
+       {
+           my $v;
+           for ($v = 0; $v < $dict->get_var_cnt(); $v++)
+           {
+               print "val$v: @$c[$v] ";
+           }
+           print "\n";
+       }
+
+
+=cut