Array manipulation how to

chessgui has asked for the wisdom of the Perl Monks concerning the following question:

I wonder if there is a ~~more elegant~~ shorter way for doing some common array manipulation tasks:

swap two elements of an array

# swap $index1 and $index2 of @array
$temp=$array[$index2];
$array[$index2]=$array[$index1];
$array[$index1]=$temp;
[download]

step $index in direction $dir (+1 or -1) in array in a 'circular' way:

# step $index in $dir direction in @array circular
$index+=$dir;
$index=0 if $index>=@array;
$index=@array-1 if $index<0;
[download]

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Re: Array manipulation how to by moritz (Cardinal) on Feb 07, 2012 at 08:53 UTC
swap two elements of an array `@array[$index1, $index2] = @array[$index2, $index1];` [download] step $index in direction $dir (+1 or -1) in array in a 'circular' way: `$index = ($index + $dir) % @array; print $array[$index];` [download] Perl 6 - second systems done right	[reply] [d/l] [select]
Re^2: Array manipulation how to by jwkrahn (Abbot) on Feb 07, 2012 at 11:07 UTC
`$index = ($index + $dir) % @array;` [download] Or: `( $index += $dir ) %= @array;` [download]	[reply] [d/l] [select]
Re^2: Array manipulation how to by chessgui (Scribe) on Feb 07, 2012 at 09:25 UTC
What kind of sytax is this: `@array[$index1,$index2]`? What does this exactly mean?	[reply] [d/l]
Re^3: Array manipulation how to by moritz (Cardinal) on Feb 07, 2012 at 09:47 UTC
It's an array slice, and it returns multiple of the array elements. perldata describes it in more detail. Perl 6 - second systems done right	[reply]
Re: Array manipulation how to by Ratazong (Monsignor) on Feb 07, 2012 at 08:54 UTC
Hi! for 1., be inspired by the following code: `my $x = 5; my $y = 2; ($x, $y) = ($y, $x); print ("$x $y\n");` [download] for 2., check here in the FAQ on how to handle circular lists HTH, Rata	[reply] [d/l]
Re: Array manipulation how to by chessgui (Scribe) on Feb 07, 2012 at 11:21 UTC
Let me add one more: rotate an array left/right `# rotate @array left my $temp=shift @array; push(@array,$temp); # rotate @array right my $temp=pop @array; unshift(@array,$temp);` [download]	[reply] [d/l]
Re^2: Array manipulation how to by JavaFan (Canon) on Feb 07, 2012 at 11:32 UTC
And without an additional variable: `push @a, shift @a; unshift @a, pop @a;` [download]	[reply] [d/l]
Re^3: Array manipulation how to by chessgui (Scribe) on Feb 07, 2012 at 11:39 UTC
would this work? `@_=@a; push, shift; @_=@a; unshift, pop;` [download]	[reply] [d/l]
Re^4: Array manipulation how to by choroba (Cardinal) on Feb 07, 2012 at 11:48 UTC
Re^4: Array manipulation how to by JavaFan (Canon) on Feb 07, 2012 at 12:30 UTC
Re: Array manipulation how to by Anonymous Monk on Feb 07, 2012 at 12:36 UTC
Beware low-flying golf balls...	[reply]