slicing array based on values but not index

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

I have an array of arrays (sorted one), and I am looking in for a way to slice the elements based on a particular column values. An Example might help,

@arr = ([12, "abc", 30],
        [24, "abc", 30],
        [26, "abc", 30],
        [14, "abc", 40],
        [46, "abc", 40],
        [2, "abc", 50]);

#I want to slice them based on column 3, such that

@arr1 = ([12, "abc", 30],
         [24, "abc", 30],
         [26, "abc", 30]);

@arr2 = ([14, "abc", 40],
         [46, "abc", 40]);

@arr3 = ([2, "abc", 50]);
[download]

And yes, the values in column 3 aren't fixed one. They can be any number, and I want to group arrays based on its value.

Any help will be appreciated.

Comment on slicing array based on values but not index Download Code

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Re: slicing array based on values but not index by Bloodnok (Vicar) on Aug 13, 2009 at 21:14 UTC
You mean something like: `use warnings; use strict; use Data::Dumper; my @arr = ( [12, "abc", 30], [24, "abc", 30], [26, "abc", 30], [14, "abc", 40], [46, "abc", 40], [2, "abc", 50] ); my %res; map { push @{$res{$_->[2]}}, $_ } @arr; warn Dumper values %res;` [download] Giving: `$ perl tst.pl $VAR1 = [ [ 2, 'abc', 50 ] ]; $VAR2 = [ [ 14, 'abc', 40 ], [ 46, 'abc', 40 ] ]; $VAR3 = [ [ 12, 'abc', 30 ], [ 24, 'abc', 30 ], [ 26, 'abc', 30 ] ];` [download] A user level that continues to overstate my experience :-))	[reply] [d/l] [select]
Re^2: slicing array based on values but not index by suggestsome (Initiate) on Aug 13, 2009 at 21:30 UTC
Kudos!!! Please excuse my poor knowledge, can you explain how is it working?	[reply]
Re^3: slicing array based on values but not index by Bloodnok (Vicar) on Aug 13, 2009 at 21:51 UTC
`map { push @{$res{$_->[2]}}, $_ } @arr;` [download] map loops thro' all values of the array `@arr` - setting `$_` to each value (an array ref.) in turn - pushing that value onto an array in a hash keyed on the last element of each individual array. As you can see, the result you're interested in is the array of values of the newly created hash. A user level that continues to overstate my experience :-))	[reply] [d/l] [select]
Re^4: slicing array based on values but not index by suggestsome (Initiate) on Aug 13, 2009 at 22:32 UTC
Re^5: slicing array based on values but not index by ikegami (Patriarch) on Aug 13, 2009 at 22:37 UTC
Some notes below your chosen depth have not been shown here
Re: slicing array based on values but not index by bichonfrise74 (Vicar) on Aug 13, 2009 at 22:34 UTC
If you want to really pursue the answer of ssandv, you can try something below. As you can see, it is not as nice and efficient as the one given by Bloodnok. `#!/usr/bin/perl use strict; use Data::Dumper; my %record; my %third_col; my @arr = ( [12, "abc", 30], [24, "abc", 30], [26, "abc", 30], [14, "abc", 40], [46, "abc", 40], [2, "abc", 50] ); $third_col{ $_->[2] }++ for (@arr); for my $i (@arr) { push ( @{ $record{$i->[2]} }, $i ) if ( grep /$i->[2]/, keys %third_col ); } print Dumper \%record;` [download]	[reply] [d/l]
Re: slicing array based on values but not index by ssandv (Hermit) on Aug 13, 2009 at 21:26 UTC
`my @arr1 = grep {$_->[2]==30} @arr;` is one way of accomplishing something like this.	[reply] [d/l]
Re^2: slicing array based on values but not index by suggestsome (Initiate) on Aug 13, 2009 at 22:02 UTC
but that will not give remaining output where $_->2==40 or 50. And this requires to know all the values column3 can have.	[reply]
Re^3: slicing array based on values but not index by ssandv (Hermit) on Aug 13, 2009 at 22:12 UTC
grep is mighty helpful. If you can't figure out how to get all the values column 3 has, you have bigger issues, since this clearly shows how to get the value in column 3. Perlmonks isn't here to do your work for you. You need to put some of your own effort in.	[reply]