comment on

Comparing two general hierarchical data structures is in general a hard problem. First, you have to establish a criterion for equivalency. Do hash values have to be exactly the same, or is it the values' contents? Must arrays have exactly the same elements in the same order, or is it that they form equivalent sets good enough? Second, you have to come up with a search strategy.

For instance, for a hash of hashes and assuming $retrieved is a superset of $given, the following can be used:

my $result = {};
foreach my $main_key (keys %$retrieved) {
   unless (exists $given->{$main_key} ) {
      $result->{$main_key} = $retrieved->{$main_key};
      next;
   }
   # The key exists, compare subhashes
   foreach my $sub_key (keys %$main_key) {
      $result->{$main_key}{$sub_key} = $retrieved->{$main_key}{$sub_ke
+y}
         unless exists $given->{$main_key}{$sub_key}
            && $given->{$main_key}{$sub_key} eq $retrieved->{$main_key
+}{$sub_key};
   }
}
[download]

The idea is that given your data structure and equivalence criteria, you can drill down and simply do comparisons, rather than deletions. This should be quicker. For your particular application, I cannot discern your equivalence criterion, so I'll stop here.

-Mark

In reply to Re: find differences between multiple hashes by kvale
in thread find differences between multiple hashes by JYDawg

Are you posting in the right place? Check out Where do I post X? to know for sure.
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
Want more info? How to link or How to display code and escape characters are good places to start.


Don't ask to ask, just ask
	PerlMonks