NAME
Tie::CSV_File - ties a csv-file to an array of arrays
SYNOPSIS
use Tie::CSV_File;
tie my @data, 'Tie::File', 'xyz.dat';
print "Data in 3rd line, 5th column: ", $data[2][4];
untie @data;
# or to read a tabular seperated file
tie my @data, 'Tie::File', 'xyz.dat', sep_char => "\t",
quote_char => undef,
eol => undef, # default
escape_char => undef,
always_quote => 0; # default
# or to read a simple white space seperated file
tie my @data, 'Tie::File', 'xyz.dat', sep_re => qr/\s+/,
quote_char => undef,
eol => undef, # default
escape_char => undef,
always_quote => 0; # default
[NOT YET IMPLEMENTED]
$data[1][3] = 4;
$data[-1][-1] = "last column in last line";
push @data, [qw/Jan Feb Mar/];
delete $data[3][2];DESCRIPTION
Tie::File represents a regular csv file as a Perl array of arrays. The first dimension of the represents the line-nr in the original file, the second dimension represents the col-nr. Both indices are starting with 0. You can also access with the normal array value, e.g. $data[-1][-1] stands for the last field in the last line, or @{$data[1]} stands for the columns of the second line.
An empty field has the value '', while a not existing field has the value undef. E.g. about the file
"first field",,
"last field"
"the above line is empty"we can say
$data[0][0] eq "first field"
$data[0][1] eq ""
!defined $data[0][2]
$data[1][0] eq "last field"
@{$data[1]} # is an empty list ()
!defined $data[1][0]
$data[2][0] eq "the above line is empty"
!defined $data[$x][$y] # for every $x > 3, $y any Note, that it isn't possible yet to change the data.
There's only a small part of the whole file in memory, so this module will work also for large files. Please look the Tie::File module for any details, as I use it to read the lines of the file.
But it won't work with large fields, as all fields of one line are parsed, even if you only want to get one field.
CSV options for tieing
Similar to Text::CSV_XS, you can add the following options:
- quote_char {default: "} =item eol {default: undef}, =item sep_char {default: ,} =item escape_char {default: "} =item always_quote {default: 0}
Please read the documentation of Text::CSV_XS for details.
Note, that the binary option isn't available.
In addition to have an easier working with files, that aren't seperated with different characters, e.g. sometimes one whitespace, sometimes more, I added the sep_re option (defaults to undef).
If it is specified, sep_char is ignored when reading, instead something similar to split at the sepater is done to find out the fields.
E.g., you can say
tie my @data, 'Tie::File', 'xyz.dat', sep_re => qr/\s+/,
quote_char => undef,
eol => undef, # default
escape_char => undef,
always_quote => 0; # default
to read something like
PID TTY TIME CMD
1200 pts/0 00:00:00 bash
1221 pts/0 00:00:01 nedit
1224 pts/0 00:00:01 nedit
1228 pts/0 00:00:06 nedit
1318 pts/0 00:00:01 nedit
1605 pts/0 00:00:00 psNote, that the value of sep_re must be a regexp object, e.g. generated with qr/.../. A simple string produces an error.
EXPORT
None by default.
TODO
Implement a writable array of arrays.
Possibility to give (memory) options at tieing, like mode, memory, dw_size similar to Tie::File.
Implement binary mode.
Option like filter = sub { s/\s+/ / }> that would specify a routine called before a line is processed. Perhaps even process is a sensfull name to this option.
SEE ALSO
Tie::File Text::CSV Text::CSV_XS
AUTHOR
Janek Schleicher, <big@kamelfreund.de<gt>
COPYRIGHT AND LICENSE
Copyright 2002 by Janek Schleicher
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.