better way to convert a string into an array and an hash

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

Replies are listed 'Best First'.
Re: better way to convert a string into an array and an hash by dragonchild (Archbishop) on Oct 05, 2004 at 14:48 UTC
Looks good to me. I'd write it like this: `my $string = " ... "; my (@array_2, %hash_1); foreach ( split ',' => $string ) { my ($left, $right) = split ':'; push @array_2, $left; $hash_1{$left} = $right; }` [download] You don't need @array_1 at all. You should scope @array_temp more tightly. And, in fact, I would label the actual items of @array_temp. Otherwise, it looked fine. Being right, does not endow the right to be rude; politeness costs nothing. Being unknowing, is not the same as being stupid. Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence. Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.	[reply] [d/l]
Re: better way to convert a string into an array and an hash by duff (Parson) on Oct 05, 2004 at 14:53 UTC
I don't know if it's better, but you can do this: `my $string = "1:1,2:1,3:2,500:2,505:1"; my %hash = split /[:,]/, $string; my @array = keys %hash;` [download] Whether it's better depends on how much you know and can guarantee about your data. :-) duff	[reply] [d/l]
Re^2: better way to convert a string into an array and an hash by dragonchild (Archbishop) on Oct 05, 2004 at 15:08 UTC
FYI: that's not functionally equivalent. You lose the ordering in @array. Being right, does not endow the right to be rude; politeness costs nothing. Being unknowing, is not the same as being stupid. Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence. Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.	[reply]
Re^3: better way to convert a string into an array and an hash by duff (Parson) on Oct 05, 2004 at 15:27 UTC
Indeed. There are a number of ways to preserve the order. Here's a slightly whimsical one: `my $string = "1:1,2:1,3:2,500:2,505:1"; my %hash = split /[:,]/, $string; my @array = split /:.+?,?/, $string; # :-)` [download] or another: `my $string = "1:1,2:1,3:2,500:2,505:1"; my %hash = my @array = split /[:,]/, $string; @array = @array[grep $_%2==0, 0..$#array];` [download] But these probably drive the original split idea far far into the ground :-) duff	[reply] [d/l] [select]
Re: better way to convert a string into an array and an hash by davorg (Chancellor) on Oct 05, 2004 at 15:24 UTC
Slightly contrived single line solution: `#!/usr/bin/perl use strict; use warnings; $_ = '1:1,2:1,3:2,500:2,505:1'; my (@array, %hash); %hash = map { my @x = split /:/; push @array, $x[0]; @x } split /,/; use Data::Dumper; print Dumper \@array, \%hash;` [download] -- <http://www.dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l]
(Golf!) Re^2: better way to convert a string into an array and an hash by dragonchild (Archbishop) on Oct 05, 2004 at 15:31 UTC
`my (@a, %h); $_ = '1:1,2:1,3:2,500:2,505:1'; #234567890#234567890#234567890#234567890#234567890#234567890 # 47 characters ... %h=map{@@=/[^:]+/g;$a[$#a+1]=$@[0];@@}/[^,]+/g; # 44 ... %h=map{@@=/[^:]+/g;push@a,$@[0];@@}/[^,]+/g; # Based on duff's whimsy above ... 42 characters %h=@a=/[^:,]+/g;@a=@a[grep!($_%2),0..$#a]; # Further whimsy ... 29 characters %h=/[^:,]+/g;@a=/([^,:]+):/g;` [download] Rules: You can assume all the code above the counting line. Bonus points if you run under strict and warnings. Being right, does not endow the right to be rude; politeness costs nothing. Being unknowing, is not the same as being stupid. Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence. Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.	[reply] [d/l]
Re^3: better way to convert a string into an array and an hash by fergal (Chaplain) on Oct 05, 2004 at 15:45 UTC
If you convert my answer to use short variable names and remove the ?: you get 44 relevant chars `#234567890#234567890#234567890#234567890#234567890#234567890 s/(\d+):(\d+)(,\|$)/$h{$1}=$2;push(@a,$1)/ge;` [download]	[reply] [d/l]
Re^3: better way to convert a string into an array and an hash by duff (Parson) on Oct 05, 2004 at 15:50 UTC
Surely, `%h=/\d+/g;@a=/(\d+):/g;` would be closer to what's wanted :) duff	[reply] [d/l]
Re^3: better way to convert a string into an array and an hash by Rhose (Priest) on Oct 05, 2004 at 16:08 UTC
I'm not a golfer, but... `tr/:/,/;%h=eval;@a=keys%h;` Update `y/:/,/;%h=eval;@a=keys%h;` Update 2 If the ordering of @a is important, how about `@a=/(\d+):/g;y/:/,/;%h=eval;`	[reply] [d/l] [select]
Re^4: better way to convert a string into an array and an hash by dragonchild (Archbishop) on Oct 05, 2004 at 17:04 UTC
Re^3: better way to convert a string into an array and an hash by Miguel (Friar) on Oct 05, 2004 at 15:45 UTC
GEEES!!! Thank you all for showing me that I still have a lot to learn! :D Miguel	[reply]
Re: better way to convert a string into an array and an hash by fergal (Chaplain) on Oct 05, 2004 at 14:56 UTC
`use strict; use warnings; my $string = "1:1,2:1,3:2,500:2,505:1"; my (@array, %hash); $string =~ s/(\d+):(\d+)(?:,\|$)/$hash{$1}=$2;push(@array, $1)/ge; use Data::Dumper; print Dumper(\@array, \%hash);` [download] the e on the end of the s// tells perl to execute what's on the right hand side and the g tells it to match the left hand side as many times as possible. So you effectively end up with the code on the right in a loop over all the things that match the pattern. The (?:,\|$) makes sure that the pair of number si followed by a , or that we're at the end of the string. One thing to note is that this will destroy the contents of $string.	[reply] [d/l]
Re^2: better way to convert a string into an array and an hash by ikegami (Patriarch) on Oct 05, 2004 at 18:44 UTC
May I recommend `while ($string =~ /(\d+):(\d+)(?:,\|$)/g) { $hash{$1} = $2; push(@array, $1); }` [download] over `$string =~ s/(\d+):(\d+)(?:,\|$)/$hash{$1}=$2;push(@array, $1)/ge;` [download]	[reply] [d/l] [select]
Re^2: better way to convert a string into an array and an hash by ambrus (Abbot) on Oct 05, 2004 at 18:45 UTC
You are using `s///ge` only for the side effects of the code in the substitution part. Why do you need a substitution then? You could just as well say `use warnings; use strict; my $string = "1:1,2:1,3:2,500:2,505:1"; my (@array, %hash); while ($string =~ /(\d+):(\d+)(?:,\|$)/g) { $hash{$1}=$2;push(@array, $1) }; use Data::Dumper; print Dumper(\@array, \%hash);` [download]	[reply] [d/l] [select]
Re^3: better way to convert a string into an array and an hash by fergal (Chaplain) on Oct 05, 2004 at 20:50 UTC
Simply because it gives you a free loop. I first saw this idiom about 10 years ago for decoding a cgi params into a hash. Something like `$p =~ s/(.?)=(.?)(&\|$)/$v=$2;$v=~s/%(..)/chr(hex($1))/ge;$p{$1}=$v/g +e` [download] a substitution within a substiution! I also thought it might be quicker but after a quick benchmark it seems not. I suppose I could have used `[/(\d+):(\d+)(?:,\|$)(?{$hash{$1}=$2;push(@array, $1);1})/g];` [download] for a free loop without destroying the string but isn't much faster.	[reply] [d/l] [select]
Re: better way to convert a string into an array and an hash by ambrus (Abbot) on Oct 05, 2004 at 17:14 UTC
My guess is: `my $string = "1:1,2:1,3:2,500:2,505:1"; my %hash = $string=~/([-.\w]):([-.\w]),/g; my @array = $string=~/([-.\w]):/g; use Data::Dumper; print Dumper \@array, \%hash;` [download] Update:* that's wrong of course. Here's the corrected one: `my $string = "1:1,2:1,3:2,500:2,505:1"; my %hash = $string=~/([-.\w]):([-.\w])/g; @array = $string=~/([-.\w]*):/g; use Data::Dumper; print Dumper \@array, \%hash;` [download] Sorry.	[reply] [d/l] [select]


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