2d Array: Changing Elements Perl

Question

I have a 2d array in Perl. I passed the array to a subroutine and I want to modify all elements of the 2d array then return it and print the array. I have attached my code so far below. The problem I am having is actually changing each individual element and passing the array to a subroutine.

Original Matrix+Code

       x            y       z
CG  -3.74900 -4.89100 -3.45400 
OD1 -6.45900 -6.29100 -6.08000 
OD2 -1.31600 -1.83300 -0.17600   

sub translateMatrixOperation
{
my (@translatematrix, $x, $y, $z) = @_;
print "PRINTING FIRST\n";
my $arrsize = scalar @translatematrix;
for(my $i = 0; $i <= $arrsize; $i++)
{
    for(my $j = 0; $j <= $arrsize; $j++)
    {
        if ($j == 0)
        {
            print "[$i][$j]:$translatematrix[$i][$j]\n";
            $_ = $_ - $x;
        }
        elsif ($j == 1)
        {
            print "[$i][$j]:$translatematrix[$i][$j]\n";
           $_ = $_ - $y;
        }
        elsif ($j == 2)
        {
            print "[$i][$j]:$translatematrix[$i][$j]\n";
            $_ = $_ - $z;
        }
    }
}
print "PRINTING\n";
for(my $i = 0; $i <= $arrsize; $i++)
{
    for(my $j = 0; $j <= $arrsize; $j++)
    {
        print "$translatematrix[$i][$j] ";
    }
    print "\n";
}
# return (\@translatematrix);

} I want to edit the whole array by adding a constant value to the x values, a constant value to the y values, and a constant to the z. Where did I go wrong?

regarding style, for(my $i = 0; $i <= $arrsize; $i++) is commonly written as for my $i (0 .. $#arr) for @arr array — mpapec
– mpapec, Commented Aug 12, 2013 at 10:31
Did you consider using PDL? Should make matrix operations very easy. — memowe
– memowe, Commented Aug 12, 2013 at 13:18

mpapec · Accepted Answer · 2013-08-12 10:25:29Z

2

my (@translatematrix, $x, $y, $z) = @_;

does not make sense as @translatematrix slurps all elements from @_, and should be:

my ($translatematrix, $x, $y, $z) = @_;

where $translatematrix is array reference.

        $_ = $_ - $x;

should be more like

$translatematrix->[$i][$j] -= $x;

and also similar logic to $y and $z should be applied.

answered Aug 12, 2013 at 10:25

mpapec

50.7k8 gold badges72 silver badges133 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

user2657817 Over a year ago

This technique works, but it prevents me from using the current method of calculating length. How do I calculate length of the array?

mpapec Over a year ago

@user2657817 you can change parameter order ie. my ($x, $y, $z, @translatematrix) = @_; so array is last one

Collectives™ on Stack Overflow

2d Array: Changing Elements Perl

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related