>>>>> "EM" == Eric Mooshagian <[email protected]> writes:
EM> I would like a subroutine that will allow me to easily put columns
EM> of a tab delimited file into their own arrays.
EM> I've been calling the following repeatedly for each column:
EM> my @array1 = getcolvals($filehandle, 0);
EM> my @array2 = getcolvals($filehandle, 1); ...etc.
whenever you think you need to name things with numeric parts, you
usually need an array. since you want arrays, then you really want an
array of arrays.
EM> sub getcolvals {
EM> @_ and not @_ % 2 or die "Incorrect number of arguments to
getcolvals!\n";
that is sort of clunky. why not just check @_ == 2?
@_ == 2 or die ...
EM> my $myfile = shift;
EM> my $mycol = shift;
it is usually better to assign from @_. i posted not to long ago several
reasons why. check the archives for it.
my( $myfile, $mycol ) = @_ ;
and in this case you won't need a $mycol since the code will load all
the columns into arrays.
EM> my @column = ();
you don't need to initialize my arrays to () as my does that for you.
EM> while (<$myfile>) {
this will fail unless you reopen the file each time you call the sub or
you seek to the beginning of the file.
EM> my ($field) = (split /\s/, $_)[$mycol];
since you are slicing the split and getting one value, you don't need
the () around $field.
EM> push @column, $field;
and you can combing both of those lines into one:
push @column, (split /\s/, $_)[$mycol] ;
EM> }
EM> return @column;
EM> }
this is untested:
# this is a faster and easier way to get lines from a file
use File::Slurp ;
sub load_columns {
my( $file_name ) = @_ ;
$file_name or die 'load_columns: missing file name' ;
my @lines = read_file $file_name ;
my $matrix ;
foreach my $line ( @lines ) {
my @fields = split ' ', $line ;
for my $i ( 0 .. $#fields ) {
# build up the array of arrays here. each array gets the next field value
push( @{$matrix[$i]}, $field[$i] ) ;
}
}
return $matrix ;
}
for more on references and perl data structures read:
perlreftut
perllol
perldsc
uri
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