NAME

PDL::IO::CSV - Create PDL from CSV file (optimized for speed and large data)

SYNOPSIS

my $pdl = rcsv2D($csv_filename_or_filehandle);
#or
my $pdl = rcsv2D($csv_filename_or_filehandle, \@column_ids);
#or
my $pdl = rcsv2D($csv_filename_or_filehandle, \%options);
#or
my $pdl = rcsv2D($csv_filename_or_filehandle, \@column_ids, \%options);

DESCRIPTION

The traditionall way of creating PDL piddle from CSV data is via rcols function.

my $pdl = rcols("data.csv", [1..4], { DEFTYPE=>double, COLSEP=>"," });

This module provides alternative implementation based Text::CSV_XS which should be significantly faster than traditional approach.

FUNCTIONS

rcsv1D

Loads data from CSV file into 1D piddles (separate for each column).

my ($pdl1, $pdl2, $pdl3) = rcsv1D($csv_filename_or_filehandle);
#or
my ($pdl1, $pdl2, $pdl3) = rcsv1D($csv_filename_or_filehandle, \@column_ids);
#or
my ($pdl1, $pdl2, $pdl3) = rcsv1D($csv_filename_or_filehandle, \%options);
#or
my ($pdl1, $pdl2, $pdl3) = rcsv1D($csv_filename_or_filehandle, \@column_ids, \%options);

Items supported in options hash:

• type

  Defines the type of output piddles: double, float, longlong, long, short, byte. Default value is double.

  You can set one type for all columns/piddles:

    my ($a, $b, $c) = rcsv1D($csv, {type => double});
  

  or separately for each colum/piddle:

    my ($a, $b, $c) = rcsv1D($csv, {type => [long, double, double]});
  

• fetch_chunk

  We do not try to load all CSV data into memory at once, we load them in chunks defined by this parameter. Default value is 40000 (CSV rows).

• reshape_inc

  As we do not try to load the whole CSV file into memory at once, we also do not know at the beginning how many rows there will be. Therefore we do not know how big piddle to allocate, we have to incrementally (re)alocated the piddle by increments defined by this parameter. Default value is 80000.

  If you know how many rows there will be you can improve performance by setting this parameter to expected row count.

• empty2bad

  Values 0 (default) or 1 - convert empty cells to BAD values (there is a performance cost when turned on). If not enabled the BAD values are silently converted into 0.

• text2bad

  Values 0 (default) or 1 - convert values that don't pass looks_like_number check to BAD values (there is a significant performance cost when turned on). If not enabled these non-numerical values are silently converted into 0.

• header

  Values 0 (default) or 1 - consider the first line as column headers (it is ignored but must have the same count of columns as the rest of the CSV file).

• decimal_comma

  Values 0 (default) or 1 - accept , (comma) as a decimal separator (there is a performance cost when turned on).

• encoding

  Optional enconding e.g. :utf8 (default undef) that will be applied on input filehandle.

• debug

  Values 0 (default) or 1 - turn on/off debug messages

• sep_char

  Value separator, default value , (comma).

• and all other options valid for new method of Text::CSV_XS

rcsv2D

Loads data from CSV file into 2D piddle.

my $pdl = rcsv2D($csv_filename_or_filehandle);
#or
my $pdl = rcsv2D($csv_filename_or_filehandle, \@column_ids);
#or
my $pdl = rcsv2D($csv_filename_or_filehandle, \%options);
#or
my $pdl = rcsv2D($csv_filename_or_filehandle, \@column_ids, \%options);

Items supported in options hash are the same as by "rcsv1D".

wcsv1D

Saves data from one or more 1D piddles to CSV file.

wcsv1D($pdl1, $pdl2, $pdl3, $csv_filename_or_filehandle, \%options);
#or
wcsv1D($pdl1, $pdl2, $pdl3, $csv_filename_or_filehandle);
#or
wcsv1D($pdl1, $pdl2, \%options); #prints to STDOUT
#or
wcsv1D($pdl1, $pdl2);

# but also
$pdl1D->wcsv1D("file.csv");

Items supported in options hash:

• header

  Arrayref with values that will be printed as the first CSV line.

• bad2empty

  Values 0 or 1 (default) - convert BAD values into empty strings (there is a performance cost when turned on).

• encoding

  Optional enconding e.g. :utf8 (default undef) that will be applied on output filehandle.

• debug

  Values 0 (default) or 1 - turn on/off debug messages

• sep_char

  Value separator, default value , (comma).

• eol

  New line separator, default value \n (UNIX newline).

• and all other options valid for new method of Text::CSV_XS

wcsv2D

Saves data from one 2D piddle to CSV file.

wcsv2D($pdl, $csv_filename_or_filehandle, \%options);
#or
wcsv2D($pdl, $csv_filename_or_filehandle);
#or
wcsv2D($pdl, \%options); #prints to STDOUT
#or
wcsv2D($pdl);

# but also
$pdl->wcsv2D("file.csv");

Items supported in options hash are the same as by "wcsv1D".

SEE ALSO

PDL, Text::CSV_XS

LICENSE

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

COPYRIGHT

2014+ KMX kmx@cpan.org