Shell Programming and Scripting

Hi,

Could someone please help me with this? I have two arrays and I need to generate third array containing difference between the two. For example -

@Array1 = [1,5,15,20];
@Array2 = [15,1];

I would like to find difference between these two and generate third array that contains the difference. In this case it would look like -

Array3 - [5,20];

Could anyone please help how to do this in perl?

Thanks,

---------- Post updated at 05:33 PM ---------- Previous update was at 04:40 PM ----------

Nevermind. I found the solution. This is what I am doing now -

foreach $wrkelement (@Array1, @Array2) { $count{$element}++ }
foreach $element (keys %count) {
push @{ $count{$element} > 1 ? \@Intersection : \@Difference }, $element;
}


@Difference is the Array3 I was looking for - difference between values in two arrays

Though, if someone has any better way of doing then plz let me know. I would love to know!

Thanks,

Code:

$
$ perl -le '@x=(1,5,15,20); @y=(15,1); %y=map{$_=>1} @y;
>           @diff=grep(!defined $y{$_}, @x);
>           print foreach (@diff)'
5
20
$

tyler_durden

No loops are needed:

Code:

my @a1, @a2, %diff1, %diff2;
@a1 = (1, 5, 10, 15);
@a2 = (5, 15, 25);

@diff1{ @a1 } = @a1;
delete @diff1{ @a2 };
# %diff1 contains elements from '@a1' that are not in '@a2'

@diff2{ @a2 } = @a2;
delete @diff2{ @a1 };
# %diff2 contains elements from '@a2' that are not in '@a1'

@k = (keys %diff1, keys %diff2);
print "keys = @k\n";

In @k are the values that make up the difference.

A bit off-topic, but it may be interesting to know that Ruby has the most intuitive solution for this problem:

Code:

$
$ ruby -e 'a1 = [1,5,15,20]; a2 = [15,1]; puts a1 - a2'
5
20
$
$ ruby -e 'puts [1,5,15,20] - [15,1]'
5
20
$

tyler_durden

Hey, that is pretty cool. One more reason to put Ruby on my list of languages to play around with...

Its all there available, don't reinvent the wheel

Try this,
List::Compare - search.cpan.org

---------- Post updated at 09:40 AM ---------- Previous update was at 09:07 AM ----------


Is this working?
1. Context used is wrong
2. First loop should use $wrkelement and $element

Or, was that just a sample?