in reply to Re^2: Working out frequency statistics with perl
in thread Working out frequency statistics with perl

I don't understand the subroutine that was posted earlier. I don't understand what I am supposed to pass to items?

A list of numbers from which you want to build your histogram. And it doesn't have to be sorted.

Your sample data generates this histogram for me: 

0: 67
30: 73
60: 93
90: 75
120: 26
150: 18
180: 10
210: 5
240: 2
270: 1
300: 1
330: 2
360: 1
390: 1
450: 1
840: 1

[download]

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Re^4: Working out frequency statistics with perl
by wishartz (Beadle) on Jul 16, 2008 at 12:48 UTC
    Please excuse my ignorance, but I'm not sure where to call the subroutine build histogram, and how to print out the returned result hash. I think I'm going about this in the wrong way. I tried this: 
    open(READMAP, "$command  |") || error_exit("Cannot run readmap, $!"); 
+#run the readmap command
while(<READMAP>) {    #loop through the output of the readmap command
        if (/StageTime/){
        @fields = split/\s+/;                                         
+  #Split the output by white space
        chop $fields[9];                                              
+  # Remove the period after the last digit
        $diskxStats[$i]{'filesize'}=$fields[2];
        $diskxStats[$i]{'ftptime'}=$fields[5];
        $diskxStats[$i]{'stagetime'}=$fields[9];
        if ( $fields[5] != 0 ){
        $diskxStats[$i]{'transferRate'} = $fields[2] / $fields[5];
        }
        else{
        $diskxStats[$i]{'transferRate'} = $fields[2];
        }
        if ( $fields[9] != 0 ){
        $diskxStats[$i]{'stagerate'} = $fields[2] / $fields[9];
        }
        else{
        $diskxStats[$i]{'stagerate'} = $fields[2];
        }
        $i++;
        }
}



for $i (0 .. $#diskxStats ) {
        build_histogram ($bin_stage, $diskxStats[$i]{'stagetime'});
        }

sub build_histogram {
   my ($bucket_size, @items) = @_;
   my %result;
   for (@items) {
       my $bucket = $bucket_size * floor($_ / $bucket_size);
  #     print "$bucket\n";
       $result{$bucket}++;
   }
   return %result;
}

    [download]
    Which is obviously incorrect, but not sure what I need to change to get the results you got?
[reply]
[d/l]
      In your case you would have to extract the single diskstats into an array again : 
      build_histogram ($bin_stage, map $_->{'stagetime'},@diskxStats );

      [download]
      This is equivalent to the following code which might or might not be easier to understand: 
      my @statetime=();
foreach (@diskxStats) {
  push @statetime, $_->{'stagetime'};
}
build_histogram ($bin_stage, @statetime );

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[d/l]
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