in reply to Re: Printing multiple arrays as multiple column
in thread Printing multiple arrays as multiple column
I'ts always seemed to me regrettable that List::MoreUtils chose to take the iterator approach to this. I find the transpose function a lot more useful:
As shown above, iterating throught the transpose is as easy as iterating through any other array, and much more flexible (e.g. one can easily iterate through the rows in reverse order, etc.).sub transpose { map { my $i = $_; [ map $_->[ $i ], @_ ] } 0 .. $#{ $_[0] } } my @array1 = qw /ab bc cd de/; my @array2 = qw /cc dd ee gg/; my @array3 = qw /12 34 56 78/; print "@$_\n" for transpose \( @array1, @array2, @array3 ); __END__ ab cc 12 bc dd 34 cd ee 56 de gg 78
One handy use for the transpose is to feed multi-arg functions via map; e.g.:
Plus, the transpose of a numerical matrix is a mathematically useful entity of its own right (though admittedly, one wouldn't use Perl AoA's for serious matrix-oriented computation, but rather something like PDL.)my @firsts = ( 1, 2, 3, 4 ); my @seconds = qw( w x y z ); my @thirds = ( 5.6, 7.8, 9.0, 1.2 ); my @foos = map foo( @$_ ), transpose \( @firsts, @seconds, @thirds ); # @foos gets foo( 1, 'w', 5.6 ), foo( 2, 'x', 7.8 ), etc.
the lowliest monk
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