Thanks for the reply. No, it's not. The first column is the data is a switch variable, I need to grab that value from the line and put the rest of the line into the histogram. Each array element should be a key except for the first.

I want to shove the rest of the array into the keys, loop through the next lines and counts as values

Each array element should be a key except for the first

Maybe I had misread this line when I wrote my previous answer. Possibly you really want something like this:

$hash1{$_}++ for @elements;
[download]

Example under the debugger:

  DB<1>  @elements = qw/ 1 3 5 4 6/;

  DB<2> $hash1{$_}++ for @elements;

  DB<3> x \%hash1
0  HASH(0x600509af0)
   1 => 1
   3 => 1
   4 => 1
   5 => 1
   6 => 1
[download]

Thanks for reply.

At the end, I would expect 3 histograms with the keys being elements of the array and values equal to the count.

line = "0 1 6 2 68fd1e64 80e26c9b 1f89b562 e5ba7672"

0 is the variable for the switch, the rest of the line needs to be put into keys and then count/increment.

hist1={
  "0" => 43,
  "0468d672" => 1,
  "05db9164" => 7,
  "07c540c4" => 2,
  "0a519c5c" => 1,
  "0b153874" => 14,
  "1" => 11,
  "10" => 1,
  "14" => 1,
  "15" => 1,
  "18" => 1,
  "1e88c74f" => 2,
  "1f89b562" => 3,
  "2" => 9,
  "241546e0" => 1,
  "287130e0" => 1,
  "287e684f" => 1,
  "2c16a946" => 2,
}

hist2={
  "6c9c9cf3" => 1,
  "7" => 2,
  "776ce399" => 4,
  "7cd19acc" => 1,
  "8" => 1,
  "80e26c9b" => 2,
  "8cf07265" => 2,
  "8efede7f" => 1,
  "9b5fd12f" => 1,
  "ad4527a2" => 1,
  "ae46a29d" => 1,
  "b0660259" => 1,
  "bc6e3dc1" => 1,
  "be589b51" => 1,
  "d4bb7bd8" => 3,
  "d833535f" => 1,
  "e5ba7672" => 7,
  "f0cf0024" => 2,
}

hist3={
  "3" => 2,
  "31" => 1,
  "3486227d" => 1,
  "361384ce" => 1,
  "37e4aa92" => 1,
  "38a947a1" => 1,
  "38d50e09" => 1,
  "3c9d8785" => 1,
  "4" => 3,
  "439a44a4" => 1,
  "5" => 3,
  "510b40a5" => 1,
  "5a9ed9b0" => 1,
  "6" => 1,
  "64523cfa" => 1,
  "68fd1e64" => 5,
}
[download]

An array cannot be the key of a hash. Perl stringifies hash keys, so that hash keys are always strings. Even if you tried something like this:

$hash1{\@elements}++;
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or

$hash1{[@elements]++;
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it would not work, because your key would end up being a stringified array ref (and the array content would be lost).

So either you want to use the string that you've read to be the hash key

$hash1{$line}++;
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but that does not seem to be very useful in this context, or you want to store an array reference into the value of the hash

$hash1{"some key"} = \@elements;
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but then I am not sure what you would want your key to be.

I think you need to have (and provide us) a clearer idea of the data structure that you want to have at the end of your process.

Quite possibly you really need an array of arrays, rather than a hash of arrays. Quick demonstration under the Perl debugger:

  DB<1>  @elements = qw/ 1 3 5 4 6/;

  DB<2> push @array, \@elements;

  DB<3>  @elements2 = qw/ 12 13 14 15/;

  DB<4> push @array, \@elements2;

  DB<5> x \@array
0  ARRAY(0x600509af0)
   0  ARRAY(0x600500b38)
      0  1
      1  3
      2  5
      3  4
      4  6
   1  ARRAY(0x600500928)
      0  12
      1  13
      2  14
      3  15
[download]

Update: Perhaps I misunderstood your requirement. Please read my next answer on Aug 17, 2014 at 08:50 UTC (immediately below)