Beefy Boxes and Bandwidth Generously Provided by pair Networks
Syntactic Confectionery Delight
 
PerlMonks  

Re^2: Printing multiple arrays as multiple column

by tlm (Prior)
on Apr 12, 2005 at 12:58 UTC ( [id://446968]=note: print w/replies, xml ) Need Help??


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:

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
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.).

One handy use for the transpose is to feed multi-arg functions via map; e.g.:

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.
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.)

the lowliest monk

Replies are listed 'Best First'.

Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Node Status?
node history
Node Type: note [id://446968]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others rifling through the Monastery: (7)
As of 2024-04-19 15:22 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found