Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl-Sensitive Sunglasses

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

Sounds to me like foreach (and perhaps map) and hashes will help you:

my @array_of_objects = ( { sex=>'Male', occupation=>'foo' }, { sex=>'Female', occupation=>'foo' }, { sex=>'Male', occupation=>'bar' }, { sex=>'Female', occupation=>'bar' }, { sex=>'Female', occupation=>'foo' }, ); my %counts; $counts{ $_->{sex} }++ for @array_of_objects; my %grouped; $grouped{ $_->{sex} }{ $_->{occupation} }++ for @array_of_objects; use Data::Dumper; print Dumper( \%counts, \%grouped ); __END__ $VAR1 = { 'Female' => 3, 'Male' => 2 }; $VAR2 = { 'Female' => { 'bar' => 1, 'foo' => 2 }, 'Male' => { 'foo' => 1, 'bar' => 1 } };

Update: Personally, I'd prefer the above, but if you really want a generic function, here's one option. Probably not the most efficient solution because it's recursive, I don't think the morning caffeine has fully kicked in yet ;-) Input and output is the same as above. (Update: huck's solution, posted before the below, is the non-recursive variation of this.)

sub count { my ($data, $fields) = @_; $fields = [$fields] unless ref $fields; my $count = {}; _dive( $count, $_, @$fields ) for @$data; return $count; } sub _dive { my ($ref, $obj, @path) = @_; my $targ = \$ref->{ $obj->{ shift @path } }; if (!@path) { $$targ++; return $ref } $$targ = _dive( $$targ, $obj, @path ); } print Dumper( count(\@array_of_objects, 'sex') ); print Dumper( count(\@array_of_objects, ['sex','occupation']) );

Update 2: In the above, I'm working with hash references instead of objects. If you want to use real objects and method calls, then in the first example, replace { $_->{sex} }{ $_->{occupation} } with { $_->sex }{ $_->occupation }, and in the second example, replace $obj->{ shift @path } with $obj->${\shift @path}.

In reply to Re: SQL like query over iterable in perl (updated x2) by haukex
in thread SQL like query over iterable in perl by pwagyi

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • 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 or How to display code and escape characters are good places to start.
Log In?

What's my password?
Create A New User
Domain Nodelet?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others rifling through the Monastery: (3)
As of 2022-05-22 16:21 GMT
Find Nodes?
    Voting Booth?
    Do you prefer to work remotely?

    Results (80 votes). Check out past polls.