Hi all, I am currently learning PDL and I've come up against a situation for which I cannot figure out how to proceed. I have a 2D array, comprised of multiple 1D byte vectors which may or may not be unique. I wish to count the number of unique vectors within the array - essentially a histogram of vector counts. My data is too big for here, but the following example demonstrates the issue I am having.

pdl> p $x
[
 [0 1 2]
 [3 4 5]
 [6 7 8]
 [0 1 2]
 [0 1 2]
 [6 7 8]
]

[download]

I know I can retrieve a list of unique elements:

pdl> p uniq $x
[0 1 2 3 4 5 6 7 8]

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I know I can retrieve a histogram of all elements:

pdl> p scalar hist $x,0,256,1
[3 3 3 1 1 1 2 2 2 0 0 0 0 0 ....]

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What I would like is something like the following output:

[0 1 2] 3
[3 4 5] 1
[6 7 8] 2

[download]
I think my issue stems from the fact that PDL is designed for operations on PDL elements. I am currently contemplating if the best solution to my problem is to have a lookup table of the data I am putting in vectors to an index, for example: 
my %lookup = (
  0 => "0 1 2",
  1 => "3 4 5",
  2 => "6 7 8",
);

# Then $x reduces down to
$x = [ 0 1 2 0 0 2 ];

[download]

Any advice would be welcome, as both PDL and numerical computing are new to me, thanks!

In reply to Counting PDL vectors in a PDL matrix by mxb

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