# NAME PDL::IO::CSV - Load/save PDL from/to CSV file (optimized for speed and large data) # SYNOPSIS use PDL; use PDL::IO::CSV ':all'; my $pdl = rcsv2D('input.csv'); $pdl *= 2; wcsv2D($pdl, 'double.csv'); my ($pdl1, $pdl2, $pdl3) = rcsv1D('input.csv', [0, 1, 6]); wcsv1D($pdl1, 'col2.csv'); #or $pdl2->wcsv1D('col2.csv'); $pdl2->wcsv1D('col2_tabs.csv', {sep_char=>"\t"}); # DESCRIPTION The traditional way of creating PDL piddle from CSV data is via [rcols](https://metacpan.org/pod/PDL::IO::Misc#rcols) function. my $pdl = rcols("data.csv", [1..4], { DEFTYPE=>double, COLSEP=>"," }); This module provides alternative implementation based on [Text::CSV\_XS](https://metacpan.org/pod/Text::CSV_XS) which should be significantly faster than traditional approach. PDL::IO::CSV supports reading CSV data and creating PDL piddle(s) as well as saving PDL data to CSV file. # FUNCTIONS By default, PDL::IO::CSV doesn't import any function. You can import individual functions like this: use PDL::IO::CSV qw(rcsv2D wcsv2D); Or import all available functions: use PDL::IO::CSV ':all'; ## rcsv1D Loads data from CSV file into 1D piddles (separate for each column). my ($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); Parameters: - csv\_filename\_or\_filehandle Path to CSV file to be loaded or a filehandle open for reading. - column\_ids Optional column indices (0-based) defining which columns to load from CSV file. Default is `undef` which means to load all columns. Items supported in **options** hash: - type Defines the type of output piddles: `double`, `float`, `longlong`, `long`, `short`, `byte`. Default value is `double`. **BEWARE:** type \`longlong\` can be used only on perls with 64bitint support. You can set one type for all columns/piddles: my ($a, $b, $c) = rcsv1D($csv, {type => double}); or separately for each column/piddle: my ($a, $b, $c) = rcsv1D($csv, {type => [long, double, double]}); Special datetime handling (you need to have [PDL::DateTime](https://metacpan.org/pod/PDL::DateTime) installed): my ($a, $b, $c) = rcsv1D($csv, {type => [long, 'datetime', double]}); # piddle $b will be an instance of PDL::DateTime or you cat let PDL::IO::CSV try to detect datetime columns (detection is based only on the first csv line) my ($a, $b, $c) = rcsv1D($csv, {detect_datetime=>1}); - detect\_datetime Values `0` (default) or `1`. Try to detect datetime columns, corresponding output piddles will be instances of [PDL::Datetime](https://metacpan.org/pod/PDL::Datetime) (which you need to have installed). - 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)allocated 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 empty values are silently converted into `0`. - text2bad Values `0` (default) or `1` - convert values that don't pass [looks\_like\_number](https://metacpan.org/pod/Scalar::Util#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 `N` (positive integer) - consider the first `N` lines as headers and skip them. BEWARE: we are talking here about skipping CSV lines which in some cases might be more than 1 text line. NOTE: header values (if any) are considered to be column names and are stored in loaded piddles in $pdl->hdr->{col\_name} NOTE: `rcsv1D` accepts a special `header` value `'auto'` which skips rows (from beginning) that have in all columns non-numeric values. - 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](https://metacpan.org/pod/Text::CSV_XS#new) method of [Text::CSV\_XS](https://metacpan.org/pod/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); Parameters and items supported in `options` hash are the same as by ["rcsv1D"](#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 as a piddle method $pdl1D->wcsv1D("file.csv"); NOTE: piddles piddles are instances of [PDL::DateTime](https://metacpan.org/pod/PDL::DateTime) are exported by wcsv1D as ISO 8601 strings. Parameters: - piddles One or more 1D piddles. All has to be 1D but may have different count of elements. - csv\_filename\_or\_filehandle Path to CSV file to write to or a filehandle open for writing. Default is STDOUT. Items supported in **options** hash: - header Arrayref with values that will be printed as the first CSV line. Or `'auto'` value which means that column names are taken from $pdl->hdr->{col\_name}. - bad2empty Values `0` or `1` (default) - convert BAD values into empty strings (there is a performance cost when turned on). - encoding Optional enconding e.g. `:utf8` (default `undef`) that will be applied on output filehandle. - debug Values `0` (default) or `1` - turn on/off debug messages - sep\_char Value separator, default value `,` (comma). - eol New line separator, default value `\n` (UNIX newline). - and all other options valid for [new](https://metacpan.org/pod/Text::CSV_XS#new) method of [Text::CSV\_XS](https://metacpan.org/pod/Text::CSV_XS) ## wcsv2D Saves data from one 2D piddle to CSV file. wcsv2D($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 as a piddle method $pdl->wcsv2D("file.csv"); Parameters and items supported in `options` hash are the same as by ["wcsv1D"](#wcsv1d). # SEE ALSO [PDL](https://metacpan.org/pod/PDL), [Text::CSV\_XS](https://metacpan.org/pod/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