Char

NAME

PDL::Char -- PDL subclass which allows reading and writing of fixed-length character strings as byte PDLs

SYNOPSIS

 use PDL;
 use PDL::Char;

 my $pchar = PDL::Char->new( [['abc', 'def', 'ghi'],['jkl', 'mno', 'pqr']] );

 $pchar->setstr(1,0,'foo');

 print $pchar; # 'string' bound to "", perl stringify function
 # Prints:
 # [
 #  ['abc' 'foo' 'ghi']
 #  ['jkl' 'mno' 'pqr']
 # ]

 print $pchar->atstr(2,0);
 # Prints:
 # ghi

DESCRIPTION

This subclass of PDL allows one to manipulate PDLs of 'byte' type as if they were made of fixed length strings, not just numbers.

This type of behavior is useful when you want to work with charactar grids. The indexing is done on a string level and not a character level for the 'setstr' and 'atstr' commands.

This module is in particular useful for writing NetCDF files that include character data using the PDL::NetCDF module.

FUNCTIONS

new

Function to create a byte PDL from a string, list of strings, list of list of strings, etc.

 # create a new PDL::Char from a perl array of strings
 $strpdl = PDL::Char->new( ['abc', 'def', 'ghij'] );

 # Convert a PDL of type 'byte' to a PDL::Char
 $strpdl1 = PDL::Char->new (sequence (byte, 4, 5)+99);

 $pdlchar3d = PDL::Char->new([['abc','def','ghi'],['jkl', 'mno', 'pqr']]);

string

Function to print a character PDL (created by 'char') in a pretty format.

 $char = PDL::Char->new( [['abc', 'def', 'ghi'], ['jkl', 'mno', 'pqr']] );
 print $char; # 'string' bound to "", perl stringify function
 # Prints:
 # [
 #  ['abc' 'def' 'ghi']
 #  ['jkl' 'mno' 'pqr']
 # ]

 # 'string' is overloaded to the "" operator, so:
 # print $char;
 # should have the same effect.

setstr

Function to set one string value in a character PDL. The input position is the position of the string, not a character in the string. The first dimension is assumed to be the length of the string.

The input string will be null-padded if the string is shorter than the first dimension of the PDL. It will be truncated if it is longer.

 $char = PDL::Char->new( [['abc', 'def', 'ghi'], ['jkl', 'mno', 'pqr']] );
 $char->setstr(0,1, 'foobar');
 print $char; # 'string' bound to "", perl stringify function
 # Prints:
 # [
 #  ['abc' 'def' 'ghi']
 #  ['foo' 'mno' 'pqr']
 # ]
 $char->setstr(2,1, 'f');
 print $char; # 'string' bound to "", perl stringify function
 # Prints:
 # [
 #  ['abc' 'def' 'ghi']
 #  ['foo' 'mno' 'f']      -> note that this 'f' is stored "f\0\0"
 # ]

atstr

Function to fetch one string value from a PDL::Char type PDL, given a position within the PDL. The input position of the string, not a character in the string. The length of the input string is the implied first dimension.

 $char = PDL::Char->new( [['abc', 'def', 'ghi'], ['jkl', 'mno', 'pqr']] );
 print $char->atstr(0,1);
 # Prints:
 # jkl