Re: Generating Hash-of-List using map?

All proposals are cheating so far! Here is what you are looking for (warning: dirty code!)

my %hash = map { /^([^-]*)-(.*)$/; if( $1 eq ($a//'-') ) { push @$b, $
+2; () } else { ( $a = $1 => $b = [ $2 ] ) } } @CELLS;
[download]

Of course, should $a accidentally be identical to the bit left of the hyphen in the first element of @CELLS, then it fails...

UPDATE: Small improvement on the else branch.

Comment on Re: Generating Hash-of-List using map? Select or Download Code

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Re^2: Generating Hash-of-List using map? by LanX (Saint) on Sep 23, 2013 at 21:12 UTC
I have the suspicion that this only works with sorted input while the "cheating propsosals" always work... `DB<148> %hash=() DB<149> @CELLS => ("A-1", "A-2", "A-3", "A-4", "B-5", "B-6", "C-7", "C-8", "A-9") DB<150> %hash = map { /^([^-])-(.)$/; if( $1 eq ($a//'-') ) { push + @$b, $2; () } else { ( $a = $1 => $b = [ $2 ] ) } } @CELLS; => ("B", [5, 6], "C", [7, 8], "A", [9])` [download] oops, indeed! ;-) Cheers Rolf ( addicted to the Perl Programming Language)	[reply] [d/l]
Re^3: Generating Hash-of-List using map? by hdb (Monsignor) on Sep 24, 2013 at 06:17 UTC
Oh, #@%$Ł"! I admit defeat. A sort is probably not what the OP specified. One could build a full temporary hash in the map but that would be cheating as well (also relies on `$a` not been used for anything else before): `my %hash = map { /^([^-])-(.)$/; exists $$a{$1}? (push(@{$$a{$1}},$2 +) and ()): ( $1=>$$a{$1}=[$2] ) } @CELLS;` [download] So there is really no way around first declaring the hash and then filling it. What a pity!	[reply] [d/l] [select]
Re^4: Generating Hash-of-List using map? by LanX (Saint) on Sep 24, 2013 at 10:19 UTC
> So there is really no way around first declaring the hash and then filling it. What a pity! O come on! Just "cheat"! ;-) `DB<113> @CELLS = ("A-1", "B-2", "C-3", "A-4", "B-5", "C-6", "A-7", " +B-8", "C-9") => ("A-1", "B-2", "C-3", "A-4", "B-5", "C-6", "A-7", "B-8", "C-9") DB<114> %hash = map { /^([^-])-(.)$/; if( $1 eq ($a//'-') ) { push + @$b, $2; () } else { ( $a = $1 => $b = [ $2 ] ) } } sort @CELLS; => ("A", [1, 4, 7], "B", [2, 5, 8], "C", [3, 6, 9])` [download] Cheers Rolf ( addicted to the Perl Programming Language)	[reply] [d/l]