I have a 2D array. I can get a given column of it with the following:
my @column_zero=map {$_->[0]} @{$twod_array};
Then I can manipulate @column_zero at will.
But how do I place it back into the two dimensional array?
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Do you operate on rows too? if not, perhaps you'd be better off swapping your rows and columns in your array, to match Perl's row-major ordering.Len Jaffe– Len Jaffe2012-12-23 18:52:33 +00:00Commented Dec 23, 2012 at 18:52
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I operate on everything.john-jones– john-jones2012-12-23 19:11:28 +00:00Commented Dec 23, 2012 at 19:11
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2 Answers
Perhaps it's better to get references to the values instead:
my @ref_to_column_zero = map { \($_->[0]) } @{$twod_array};
... so you can manipulate these values directly: you just need to remember that there are references stored in this array, so they should be dereferenced. For example:
for (@ref_to_column_zero) {
${ $_ } *=2;
}
If you prefer to use the old approach, you can do this:
for (0..$#column_zero) {
$twod_array->[$_][0] = $column_zero[$_];
}
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TMTOWTDI so
do{my $i; $twod_array[$i++][0] = $_ for @column_zero;};
answered Dec 23, 2012 at 21:07
Hynek -Pichi- Vychodil
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