How to juggle between two arrays that are not same size

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

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Re: How to juggle between two arrays that are not same size by kyle (Abbot) on Dec 19, 2007 at 17:19 UTC
`use Data::Dumper; @Names=qw(A B C); @FullRecord=qw(A_1 D_4 C_3 F_6 B_2); @name_presence{@Names} = (); @DesiredRecord = grep { exists $name_presence{(split /_/)[0]} } @FullRecord; print Dumper \@DesiredRecord; __END__ $VAR1 = [ 'A_1', 'C_3', 'B_2' ];` [download]	[reply] [d/l]
Re: How to juggle between two arrays that are not same size by jrsimmon (Hermit) on Dec 19, 2007 at 17:24 UTC
Have you considered a hash? `use strict; use warnings; my %Names = (A => 1, B => 1, C => 1); my %FullRecord = (A_1 => 1, D_4 => 1, C_3 => 1, F_6 => 1, B_2 => 1,); my @DesiredRecord = (); foreach my $el (keys(%FullRecord)) { my @SplitArray=split(/\_/,$el); unshift(@DesiredRecord, $el) if exists $Names{$SplitArray[0]}; } print "@DesiredRecord";` [download]	[reply] [d/l]
Re: How to juggle between two arrays that are not same size by mwah (Hermit) on Dec 19, 2007 at 18:23 UTC
the solution presented by kyle is somehow idiomatic, this would be a good choice. You can use an alternative form w/regular expressions in order to solve a more complicated pattern problem. The regex-form of kyle's solution would be like: `... my @Names = qw'A B C'; my @FullRecord = qw'A_1 D_4 C_3 F_6 B_2'; # prepare temporary dictionary my %h; @h{@Names} = (); my @DesiredRecord = grep exists $h{ [/^([^_]+)/]->[0] }, @FullRecord; print "@DesiredRecord\n"; ...` [download] Regards mwa	[reply] [d/l]
Re: How to juggle between two arrays that are not same size by perlfan (Vicar) on Dec 19, 2007 at 20:33 UTC
A straight forward way to do an intersection of two arrays (provided their elements are scalar values) is to create a hash using one array, where the keys correspond to the elements of that array. Then run over the other array, and if a key in the original hash corresponds with an element (i.e., it exists) then you've found an element in common. The following solutions ensures all unique items in the intersection, even if both arrays contain duplicate items: `my @array1 = qw/a a b b c c d d/; my @array2 = qw/ c c d d e e f f g g/; my @array3 = (); my %filter = (); foreach (@array1) { $filter{$_} = 1; } foreach (@array2) { if (exists($filter{$_}) && 2 == ++$filter{$_}) { push(@array3,$_); } } print join(' ',@array3);` [download] If your arrays are do not contain scalar values, i.e., array/hash/sub refs, etc; then you can write a function to pass `$_` through to serialize it first.	[reply] [d/l] [select]
Re: How to juggle between two arrays that are not same size by Anonymous Monk on Dec 19, 2007 at 17:25 UTC
there are probably faster solutions, but if your arrays don't get too large nested loops would be acceptable: `foreach $el (@Fullrecord) { @splitarray=split(/\_/,$el); foreach $nameel (@Names) { push (@DesiredRecord, $nameel) if ($nameel eq $splitarray[0]); } }` [download]	[reply] [d/l]


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