Count Messages for each minute, 2D array error

max210 has asked for the wisdom of the Perl Monks concerning the following question:

Hello All,
I have stored time stamp for messages coming to my system in hash and I need to count how many came for each minute. Logic is pretty simple but 2Darray is storing values where I dont want to??

my $key1=0;
my $val1=0;
my @count_message = ();

my %msg_rate = ('1', '00:00:00,284', '2', '00:00:00,462', '3', '01:01:
+00,462', '4', '00:02:00,462', '5', '01:03:00,462');
    
while( ($key1, $val1) = each(%msg_rate) ) {                  
          my ($hh1,$mm1,$ssms1) = split(/\:/,$val1);
           
          $count_message[$hh1,$mm1]++;
          print "countmsg $hh1 $mm1 = $count_message[($hh1,$mm1)]\n";
      
}
        print "Wrong Values: $count_message[(1,0)]\n";
        print "Wrong Values: $count_message[(0,3)]\n";
        print "Wrong Values: $count_message[(0,1)]\n";
        print "Wrong Values: $count_message[(1,2)]\n";
[download]

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Re: Count Messages for each minute, 2D array error by FunkyMonk (Bishop) on Apr 03, 2008 at 21:52 UTC
Had you been using strict & warnings, perl would have informed you that "`Multidimensional syntax $count_message[$hh1,$mm1] not supported`". In Perl multidimensional arrays (aka array of arrayrefs) are written: `$count_message[$hh1][$mm1]++;` [download] However, I think you'd be better off using hashes: `use Data::Dumper; my %msg_rate = ('1', '00:00:00,284', '2', '00:00:00,462', '3', '01:01: +00,462', '4', '00:02:00,462', +'5', '01:03:00,462'); my %count_per_min; while( my ($key1, $val1) = each(%msg_rate) ) { my ($hh1,$mm1,$ssms1) = split(/\:/,$val1); $count_per_min{"$hh1:$mm1"}++ } print Dumper \%count_per_min;` [download] Output: `$VAR1 = { '00:00' => 2, '00:02' => 1, '01:03' => 1, '01:01' => 1 };` [download]	[reply] [d/l] [select]
Re: Count Messages for each minute, 2D array error by ikegami (Patriarch) on Apr 03, 2008 at 21:55 UTC
The short answer: `$count_message[$hh1][$mm1]` The long answer: There's no such thing as a 2d array in Perl. However, you can store references to arrays (including references to anonymous arrays) in arrays, effectively creating a 2d array. `$a[$i][$j]` is short for `$a[$i]->[$j]` which, thanks to autovivification, is short for something like `$a[$i] \|\|= []; $a[$i]->[$j]` See perllol That said, you might be better off with a hash keyed on "hh:mm" rather than an array. I also avoid `each` since it prevents the use of `last` and `die`.	[reply] [d/l] [select]