Compare two arrays

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

Hi all,
I have to compare two string arrays. I have to check whether array1's element belong to array2 or not.
I have strings mixture of alphabets and numbers like:

array1 = {this1 this2 this11 this21 this23};
array2 = {h2this1 h3this2 h5this21 h6this23 h8this13}
[download]

i tried by

for $i(0.. $#array1){
 for $j(0.. $#array2){
  if($array2[$j]=~ /$array1[$i]/){
    print"$array1[$j] belongs to $array2[$i]";
   last;
}}}
[download]

Unfortunately, it prints as:

this1 belongs to h2this1 
this2 belongs to h3this2 
this2 belongs to h5this21 
this2 belongs to h6this23 
this1 belongs to h8this13
[download]

instead of printing it as:

this1 belongs to h2this1 
this2 belongs to h3this2 
this21 belongs to h5this21 
this23 belongs to h6this23 
this1 belongs to h8this13
[download]

I seek your advice.
Thanking you,

Comment on Compare two arrays Select or Download Code

Replies are listed 'Best First'.
Re: Compare two arrays by ELISHEVA (Prior) on Apr 02, 2009 at 10:47 UTC
You are matching "this2" to "h6this23" because your regex is missing a final dollar sign. Without the final $, matches in the middle of the string will print out. With it, only matches at the end of the string will print out. See regextut for more information on the $. So this should work: `/$array1[$j]$/` Best,beth	[reply] [d/l]
Re: Compare two arrays by almut (Canon) on Apr 02, 2009 at 10:52 UTC
...also, you've swapped `$i` and `$j`, i.e. `for $i(0.. $#array1)`, but then `$array2[$i]` (doesn't really matter in this particular case, but it would, if the arrays were of different size). It's not entirely clear what you want to achieve. The `"this1 belongs to h8this13"` in your expected output looks like you would want to do substring matching, but then, the match `"this2 belongs to h5this21"`, which you consider unfortunate, suggests you might not...	[reply] [d/l] [select]
Re: Compare two arrays by johngg (Canon) on Apr 02, 2009 at 11:44 UTC
I may be missing something but if the last line of your desired output is `this1 belongs to h8this13` then it seems logical that you would also have `this2 belongs to h5this21` and `this2 belongs to h6this23`. Anchoring the match to the end of the string drops your last desired line. Perhaps you could clarify your requirement. `use strict; use warnings; my @arr1 = qw{ this1 this2 this11 this21 this23 }; my @arr2 = qw{ h2this1 h3this2 h5this21 h6this23 h8this13 }; my @arr1Rx = map { [ $_, qr{$_\z} ] } @arr1; foreach my $e2 ( @arr2 ) { foreach my $e1 ( @arr1Rx ) { print qq{$e1->[ 0 ] belongs to $e2\n} if $e2 =~ $e1->[ 1 ]; } }` [download] The output `this1 belongs to h2this1 this2 belongs to h3this2 this21 belongs to h5this21 this23 belongs to h6this23` [download] I hope this is of interest. Cheers, JohnGG	[reply] [d/l] [select]
Re: Compare two arrays by targetsmart (Curate) on Apr 02, 2009 at 11:56 UTC
Good question this. more of this can be found in QandASection: arrays and QandASection: regular expressions I thought to provide you a relevant link to Categorized Questions and Answers, but can't. your kind of question is not found there I think that this can be moved to Categorized Questions and Answers One more question for monks, when was the last time that these Categorized Questions and Answers was updated with new questions and answers?. Is it possible to have a re-look at Categorized Questions and Answers and add some more Q&A into it. again this is a wish. Vivek -- In accordance with the prarabdha of each, the One whose function it is to ordain makes each to act. What will not happen will never happen, whatever effort one may put forth. And what will happen will not fail to happen, however much one may seek to prevent it. This is certain. The part of wisdom therefore is to stay quiet.	[reply]
Re^2: Compare two arrays by Russ (Deacon) on Apr 03, 2009 at 18:03 UTC
I'm one of the QandAEditors. Though I am, sadly, not able to spend all that much time around the Monastery anymore. It looks like you got your links to appear as you wanted. If I've missed a recent debate, my apologies for responding at face value. I might have sent the OP to How can I find the union/difference/intersection of two arrays? as well. In my almost-humble opinion, this question is better suited for SoPW since the issue was errors in the code... Wanna help keep Categorized Questions and Answers up-to-date? Russ	[reply]
Re: Compare two arrays by Bloodnok (Vicar) on Apr 02, 2009 at 11:26 UTC
Why not utilise the hash based approach outlined in Recipe 4.8 of the Perl Cookbook ?? A user level that continues to overstate my experience :-))	[reply]
Re^2: Compare two arrays by artist (Parson) on Apr 02, 2009 at 21:04 UTC
----A user level that continues to overstate my experience I guess that is why many of us are hanging here. :-)) --Artist	[reply] [d/l]
Re: Compare two arrays by leslie (Pilgrim) on Apr 02, 2009 at 11:37 UTC
Make your question clear..	[reply]


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