Re^2: add elements to array at certain positions

$i should increment each time or else the value in @a that we didn't want will still be printed after the 'I'

my $i = 0;
my @new = map { ++$i; /^[yz]$/ ? 'I' : $a[$i] } @b;
[download]

A solution I thought of with List::MoreUtils:

use List::MoreUtils qw(pairwise);
my @mine = pairwise { $b =~ /^[yz]$/ ? 'I' : $a; } @a, @b;
[download]

Mine is not as nice because it doesn't work properly if both arrays are not the same size. You would have to add a check for undefined values or pad either array to match the other array's size. Perl also warns that $a and $b are only used once.

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Re^3: add elements to array at certain positions by GrandFather (Saint) on Oct 30, 2008 at 06:55 UTC
The OP's example made it clear that no values from @a were to be skipped. $i should not increment each time, and even if it should, it should either be set to -1 before the 'loop', or incremented after the ternary. Your sample preincrements $i so $a[0] would always be skipped. Perl reduces RSI - it saves typing	[reply]
Re^4: add elements to array at certain positions by juster (Friar) on Oct 30, 2008 at 16:56 UTC
Oops, I'm sorry! I will stop posting at night before sleep. Here is a fast List::MoreUtils alternative that actually does what the OP asks for this time: `use List::MoreUtils qw(indexes); my $a = '0157953'; my $b = 'abcyefzaa'; my $new = $a; substr $new, $_, 0, 'I' foreach ( indexes { $_ =~ /^[yz]$/ } split(//, $b) ); print $new, "\n";` [download] Update: I just realized this nearly identical loop is much faster (nested update: oops it's pos-1): `substr $new, pos($b)-1, 0, 'I' while ( $b =~ /[yz]/g );` [download]	[reply] [d/l] [select]