Re: Count array element in HASH of ARRAYS

#!/usr/bin/perl -w
use strict;

my %HoA = (
   key1 => [ "50001", "01" ],
   key2 => [ "50011", "02" ],
   key3 => [ "50010", "01" ],
   key4 => [ "50041", "02" ],
   key5 => [ "50301", "02" ],
   key6 => [ "50701", "09" ],
   key7 => [ "50801", "09" ]
);

my %containers;
while (my ($k, $v) = each (%HoA)) {
    push @{$containers{$v->[0]}}, $k;
}

foreach (sort keys %containers) {
    print "Container $_ has ".@{$containers{$_}}." keys.\n"
}
[download]

This retains the keys in the `%containers` hash, if you don't need to do that you could replace the loops with:

my %containers;
while (my ($k, $v) = each (%HoA)) {
    $containers{$v->[1]}++;
}

foreach (sort keys %containers) {
    print "Container $_ has $containers{$_} keys.\n"
}
[download]

Comment on Re: Count array element in HASH of ARRAYS Select or Download Code

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Re^2: Count array element in HASH of ARRAYS by AnomalousMonk (Archbishop) on Jul 20, 2015 at 14:05 UTC
Just curious: Are the `$containers{$con} = [ ] if !exists $containers{$con};` or `$containers{$con} = 0 if !exists $containers{$con};` statements strictly (or warnings-ly) necessary with your Perl version? They aren't with 5.8.9 and 5.14.4 — but they certainly do no harm in any case. Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]
Re^3: Count array element in HASH of ARRAYS by halfcountplus (Hermit) on Jul 20, 2015 at 14:42 UTC
Seems they aren't necessary even with strict, no. I'm just prone to: `use paranoid qw(really really);` [download] Which is not to say it's a good thing. In fact I'll take those out...they might be taken to improve readability or something but not significantly IMO.	[reply] [d/l]
Re^3: Count array element in HASH of ARRAYS by stm (Initiate) on Jul 20, 2015 at 14:23 UTC
`$containers{$con} = 0 if !exists $containers{$con};` [download] Above one works. Statement "Strictly" is in use and perl version is 5.10.1, no error / warning	[reply] [d/l]
Re^2: Count array element in HASH of ARRAYS by stm (Initiate) on Jul 20, 2015 at 14:06 UTC
halfcountplus's method works. Thank you	[reply]
Re^3: Count array element in HASH of ARRAYS by Laurent_R (Canon) on Jul 20, 2015 at 16:40 UTC
Yes, fine if this gives you what you want, but, you will notice that this solution first needs to reorganize the data structure into another data structure (`%containers`) to make the counting easy. So I think that you should really not neglect stevieb's useful comment (in post Re: Count array element in HASH of ARRAYS) that it might be better to build in the first place a data structure making your requirement easier to implement. It may or may not be possible in your specific case, but if there is a way of building something like `%containers` in the first place, then you are in a much easier solution.	[reply] [d/l] [select]
Re^4: Count array element in HASH of ARRAYS by stm (Initiate) on Jul 20, 2015 at 17:46 UTC
Yes, I agree. Stevieb made a valid point. I will try that.	[reply]