NAME
Parse::CSV::Colnames - Highly flexible CSV parser including column names
(field names) manipulation
NOTE
This Module derives from Parse::CSV by Adam Kennedy inheriting its
methods. The main extensions are methods for column names manipulation
and some simple method-fixes.
SYNOPSIS
Column names manipulation makes only sense if the fields-parameter is
auto, i.e. column names are in the first line.
# Parse a colon-separated variables file from a handle as a hash
# based on headers from the first line.
my $objects = Parse::CSV::Colnames->new(
handle => $io_handle,
sep_char => ';',
fields => 'auto',
# select only rows where column name fieldname is "value"
filter => sub { if($_->{fieldname} eq "value")
{$_} else
{undef}
}
);
# get column names
my @fn=$objects->colnames
# you want lower case field names
@fn=map {lc} @fn;
# you want field names without blanks
@fn=map { s/\s+//g} @fn;
# set column names
$objects->colnames(@fn);
while ( my $object = $objects->fetch ) {
$object->do_something;
}
DESCRIPTION
This module is only an extension of Parse::CSV
For a detailed description of all methods see Parse::CSV
For a detailed description of the underlying csv-parser see Text::CSV_XS
Fixed METHODS
These methods have not work in the parent module Parse::CSV yet, because
Adam Kennedy is very busy.
combine
$status = $csv->combine(@columns);
The "combine" method is passed through to the underlying Text::CSV_XS
object. See example 3.
It sets the fields and constructs the corresponding csv string from the
arguments. You can read this array with the "fields" method.
string
$line = $csv->string;
The "string" method is passed through to the underlying Text::CSV_XS
object. See example 3 and example 4.
It returns the parsed string or the corresponding combine-setting.
print
$status = $csv->print($io, $colref);
The "print" method is passed through to the underlying Text::CSV_XS
object. See example 1.
It prints the string of the corresponding @$colref directly to an IO
handle.
Added METHODS
fields
@fields = $csv->fields;
The "fields" method is passed through to the underlying Text::CSV_XS
object.
It returns the input to "combine"-method or the actual row as an array.
colnames
@colnames = $csv->colnames("fn1","fn2") # sets colnames
or
@colnames = $csv->colnames; # gets colnames
The "colnames" method sets or gets colnames (="fields"-param). So you
can rename the colnames (hash-keys in Parse::CSV::Colnames object).
pushcolnames
@colnames = $csv->pushcolnames("fn1","fn2")
The "pushcolnames" method adds colnames at the end of $csv->colnames
(="fields"-param). You can do that if the "filter"-method adds some new
fields at the end of fields-array in Parse::CSV::Colnames object .
Please consider that these colnames or fields are not in the underlying
Text::CSV_XS object. See example 1 and example 4.
pushcombine
@colnames = $csv->pushcombine("fn1","fn2")
The "pushcombine" method adds fields at the end of the actual row
(="fields"-method) and constructs the corresponding csv string. You can
read the result with the "fields"-method. The pushcombine and
pushcolnames belong together. See example 4.
EXAMPLES
You can test these examples with copy and paste
Example 1
Using "csv->print", "csv->pushcolnames"
#!/usr/bin/perl
use strict;
use warnings;
use Parse::CSV::Colnames;
my $fh=\*DATA;
my $fhout=\*STDOUT; # only for demo
my $csv = Parse::CSV::Colnames->new(
#file => "testnamen.csv",
handle => $fh,
sep_char => ';',
fields => 'auto',
binary => 1, # for german umlauts and utf
filter => sub { $_->{country}="Germany";
$_->{product}=$_->{factor1}*$_->{factor2};
# select only rows where column name product>0
if($_->{product}>0) {
$_;
} else {
undef
}
}
);
# add colnames at the end
$csv->pushcolnames(qw(product country));
# get column names
my @fn=$csv->colnames;
# you want lower case field names
@fn=map {lc} @fn;
# you want field names without blanks
map { s/\s+//g} @fn;
# set column names
$csv->colnames(@fn);
# headerline for direct output
$csv->print($fhout,[$csv->colnames]); # print header-line
print "\n";
while(my $line=$csv->fetch) {
# csv direct output
$csv->print($fhout,[$csv->fields,$line->{product},$line->{country}]); # only input-fields are printed with method fields
print "\n";
}
__DATA__
Name;Given Name;factor1;factor2
Hurtig;Hugo;5.4;4.6
Schnallnichts;Carlo;6.4;4.6
Weissnich;Carola;7.4;4.6
Leer;Hinnerk;0;4.6
Keine Ahnung;Maximilian;8.4;4.6
Example 2
Building new fields by hand with map
#!/usr/bin/perl
use strict;
use warnings;
use Parse::CSV::Colnames;
my $fh=\*DATA;
my $csv = Parse::CSV::Colnames->new(
#file => "testnamen.csv",
handle => $fh,
sep_char => ';',
fields => 'auto',
binary => 1, # for german umlauts
filter => sub { $_->{country}="Germany";
$_->{product}=$_->{factor1}*$_->{factor2};
# select only rows where column name product>0
if($_->{product}>0) {
$_;
} else {
undef
}
}
);
#add new fieldname at the end
$csv->pushcolnames(qw(product));
# get column names
my @fn=$csv->colnames;
# you want lower case field names
@fn=map {lc} @fn;
# you want field names without blanks
map { s/\s+//g} @fn;
# set column names
$csv->colnames(@fn);
# headerline with only 2 fields
my @outcolnames1=(qw(givenname product));
print join(";",@outcolnames1) . "\n";
while(my $line=$csv->fetch) {
print join(";",map {$line->{$_}} @outcolnames1) . "\n";
}
__DATA__
Name;Given Name;factor1;factor2
Hurtig;Hugo;5.4;4.6
Schnallnichts;Carlo;6.4;4.6
Weissnich;Carola;7.4;4.6
Leer;Hinnerk;0;4.6
Keine Ahnung;Maximilian;8.4;4.6
Example 3
Using "csv->combine" and "csv->string"
#!/usr/bin/perl
use strict;
use warnings;
use Parse::CSV::Colnames;
my $fh=\*DATA;
my $csv = Parse::CSV::Colnames->new(
#file => "testnamen.csv",
handle => $fh,
sep_char => ';',
fields => 'auto',
binary => 1, # for german umlauts
filter => sub { $_->{country}="Germany";
$_->{product}=$_->{factor1}*$_->{factor2};
# select only rows where column name product>0
if($_->{product}>0) {
$_;
} else {
undef
}
}
);
$csv->pushcolnames(qw(product country));
# get column names
my @fn=$csv->colnames;
# you want lower case field names
@fn=map {lc} @fn;
# you want field names without blanks
map { s/\s+//g} @fn;
# set column names
$csv->colnames(@fn);
# headerline
my @outcolnames2=(qw(givenname product country));
$csv->combine(@outcolnames2);
print $csv->string . "\n";
while(my $line=$csv->fetch) {
# csv output
$csv->combine(map {$line->{$_}} @outcolnames2);
print $csv->string . "\n";
}
__DATA__
Name;Given Name;factor1;factor2
Hurtig;Hugo;5.4;4.6
Schnallnichts;Carlo;6.4;4.6
Weissnich;Carola;7.4;4.6
Leer;Hinnerk;0;4.6
Keine Ahnung;Maximilian;8.4;4.6
Example 4
Using "csv->pushcombine" , "csv->pushcolnames" and "csv->string"
#!/usr/bin/perl
use strict;
use warnings;
use Parse::CSV::Colnames;
my $fh=\*DATA;
my $csv = Parse::CSV::Colnames->new(
#file => "testnamen.csv",
handle => $fh,
sep_char => ';',
fields => 'auto',
binary => 1, # for german umlauts
filter => sub { $_->{country}="Germany";
$_->{product}=$_->{factor1}*$_->{factor2};
# select only rows where column name product>0
if($_->{product}>0) {
$_;
} else {
undef
}
}
);
$csv->pushcolnames(qw(product country));
# get column names
my @fn=$csv->colnames;
# you want lower case field names
@fn=map {lc} @fn;
# you want field names without blanks
map { s/\s+//g} @fn;
# set column names
$csv->colnames(@fn);
# headerline
$csv->combine($csv->colnames);
print $csv->string . "\n";
while(my $line=$csv->fetch) {
# csv output
$csv->pushcombine(map {$line->{$_}} qw(product country));
# is like
$csv->pushcombine($line->{product},$line->{country});
print $csv->string . "\n";
}
__DATA__
Name;Given Name;factor1;factor2
Hurtig;Hugo;5.4;4.6
Schnallnichts;Carlo;6.4;4.6
Weissnich;Carola;7.4;4.6
Leer;Hinnerk;0;4.6
Keine Ahnung;Maximilian;8.4;4.6
TODO
Creating Methods "popcolnames" and "popcombine". These methods delete
the last fieldnames (column names) or fields. (I will add these methods
if anybody wants this)
Creating Methods "(un)shiftcolnames" and "(un)shiftcombine". These
methods add/delete the first fieldnames (column names) or fields. (I
will add these methods if anybody wants this)
Integrating methods "getline_hr" and "column_names" of the underlying
object Text::CSV_XS.
SUPPORT
Bugs should always be reported via the CPAN bug tracker at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Parse-CSV-Colnames>
AUTHORS
Uwe Sarnowski <uwes at cpan.org>
Author of the parent modul Parse::CSV : Adam Kennedy
SEE ALSO
Parse::CSV, Text::CSV_XS
COPYRIGHT
Copyright 2011 Uwe Sarnowski
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
The full text of the license can be found in the LICENSE file included
with this module.