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

COPYRIGHT

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.

To install Parse::CSV::Colnames, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Parse::CSV::Colnames

CPAN shell

perl -MCPAN -e shell
install Parse::CSV::Colnames

For more information on module installation, please visit the detailed CPAN module installation guide.

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