to pick the common element in the array

[soubalaji]

@array1=('a',''2,'3','2');
@array2=('1','2,'3','2');
We want to pick the common element from the above two array.
there is any method to do this?
Regards,
Balaji S

[dorko]

Personally, I like List::Compare:

use strict;
use warnings;

use List::Compare;
use Data::Dumper;

my @array1=('a','2','3','2');
my @array2=('1','2','3','2');

my $lc = List::Compare->new(\@array1, \@array2);

# Get those items which appear at least once in both lists (their inte
+rsection).
my @intersection = $lc->get_intersection;
    
print Dumper \@intersection;

Also, use strict; and use warnings; caught the typos you made in defining the arrays.

Cheers,

Brent

[zentara]

Looking for something like this?

#!/usr/bin/perl
use warnings;
use strict;

my @array1=('a','2','3','2');
my @array2=('1','2','3','2');

my %in_array2 = map { $_ => 1 } @array2;

my @array3 = grep { $in_array2{$_} } @array1;

print "common @array3\n";

my %seen;
my @unique = grep{!$seen{$_}++} @array3;

print "unique @unique\n";

(code can probably be golfed down.) :-)

[Ksonar]

Hi,

I am trying to something similar but not really...

there are three arrays:

@array1 = ('Leishmania infantum','Leishmania donovani','Leishmania pan
+amensis','Leishmania braziliensis', 'Leishmania guyanensis','Leptomon
+as seymouri','Trypanosoma cruzi','Trypanosoma grayi');
@array2 = ('lin','ldo','lpa','lbr','lgu','lse','tcr','tgr');
@array3 = ('Leishmania infantum JPCM5','Leishmania infantum JPCM5','Le
+ishmania donovani','Leishmania donovani','Leishmania panamensis','Lei
+shmania braziliensis MHOM/BR/75/M2904','Leishmania panamensis','Leish
+mania braziliensis MHOM/BR/75/M2904','Leishmania guyanensis','Leptomo
+nas seymouri','Trypanosoma cruzi marinkellei','Trypanosoma cruzi','Tr
+ypanosoma cruzi strain CL Brener','Trypanosoma rangeli SC58','Trypano
+soma cruzi','Trypanosoma cruzi strain CL Brener','Trypanosoma cruzi D
+m28c','Trypanosoma cruzi','Trypanosoma theileri','Trypanosoma grayi',
+'Trypanosoma grayi');

basically I want to match array3 with array1 and then using the index position of array1, I want to pick the elements from array2.

I have used grep,~~,index, everything, but no success.

I would be great if you can help me.

[zentara]

Hi, Ksonar. You should probably post this as a new node, and put code tags around your code example.

[Anonymous Monk]

does thie code work for common elements when the following two arrays are used? my @array1=('a','2','3','2'); my @array2=('1','2','3');

[zentara]

What happens when you try?

Perl is good about doing what you mean. Usually, languages will separate ascii data from numerical data, it's called "context". The code I showed treated alphanumeric strings and numbers exactly the same. So it should work.

[Anonymous Monk]

I am new to perl can u explain the above code... Thanks

[zentara]

I'm new to being a free tutor, get a tutorial on arrays and hashes. :-) Seriously, it is some advanced code work ( which by the way, I did not write....it's been passed around in books and tutorials for a long time. The general idea is to check all array elements...dump them in a hash for counting, then check the hash keys (an array) for 1's or 0's....(or something along those general lines).

Probably every programming language has some sort of "array comparison" abilities... google for "perl array comparison", grasshopper, and when you are done reading all 5 million hits....come back and teach me. :-)

[Fletch]

It's 2. HTH. HAND. BMSMA.

Of course if that's not what you had in mind you should probably read How (Not) To Ask A Question, and see perlfaq4 for the question "How do I compute the difference of two arrays? How do I compute the intersection of two arrays?".

[Zen]

Was this necessary? I understood him quite easily.

[UnderMine]

Is position as well as value important?
i.e. from you example would you expect back @answer=(2,3); or @answer=(undef,2,3,2);
UnderMine

[JavaFan]

Actually, there's no method to do this, because the problem isn't well defined. You're asking for the common element, but there are at least two common elements, three if you consider the two 2's in each array to be distinct.