in reply to perl PDL question

What is happening is that your 2 arrays are being threaded over, however the dimensions don't match. The case that works has a 1 element pdl, which can be threaded over because pdl replicates length 1 dimensions as many times as necessary. Try this: 
my $a = sequence(10)->dummy;
my $b = pdl(2,5,7);
my $z = which(sumover($a == $b));

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This inserts a dummy dimension into $a so that $a is dimensionality (10,1) and $b is dimensionality (1,3). Dimensions of length 1 get threaded over nicely. The sumover is there to take away 1 of the dimensions (otherwise you get location in $a times location in $b) for matches

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Re^2: perl PDL question
by Anonymous Monk on Nov 27, 2007 at 11:34 UTC
    Replace sumover with any. It is more appropriate for the context.
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      The sumover part works, and produces the output array that is the appropriate indexes... brilliant!
      When I replace sumover($a==$b) with any($a==$b) I get an error though....
      perldl> $z = which(any($a == $b));
Can't call method "flat" without a package or object reference at /usr
+/lib64/perl5/site_perl/5.8.8/x86_64-linux-thread-multi/PDL/Primitive.
+pm line 1962, <STDIN> line 20.

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Re^2: perl PDL question
by nickschurch (Acolyte) on Nov 28, 2007 at 02:39 UTC
    Interestingly, this works fine from the perldl console, but in a scrip I get an error....
    my $time = rcols "testdata.txt";
my $tsearch = $time -> dummy;
print $tsearch,"\n";

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    produces:
    [njs@localhost]$ ./testcode
Use of uninitialized value in numeric lt (<) at /usr/lib64/perl5/site_
+perl/5.8.8/x86_64-linux-thread-multi/PDL/Core.pm line 936.
Use of uninitialized value in numeric lt (<) at /usr/lib64/perl5/site_
+perl/5.8.8/x86_64-linux-thread-multi/PDL/Core.pm line 939.
Use of uninitialized value in numeric gt (>) at /usr/lib64/perl5/site_
+perl/5.8.8/x86_64-linux-thread-multi/PDL/Core.pm line 942.
Use of uninitialized value in repeat (x) at /usr/lib64/perl5/site_perl
+/5.8.8/x86_64-linux-thread-multi/PDL/Core.pm line 942.
Use of uninitialized value in subtraction (-) at /usr/lib64/perl5/site
+_perl/5.8.8/x86_64-linux-thread-multi/PDL/Core.pm line 943.

[
 [ 50093.199]
 [ 50094.308]
 [ 50954.953]
 [ 51767.383]
 [ 51958.219]
 [ 52005.696]
 [ 52005.763]
 [ 52142.188]
 [ 52422.043]
 [ 52459.414]
 [ 52482.509]
 [ 52693.953]
 [ 52752.918]
 [ 52836.803]
 [ 52837.198]
 [ 53107.974]
 [ 53125.429]
 [  53141.53]
 [ 53198.495]
 [ 53243.578]
 [ 53489.381]
 [ 53603.709]
 [  53661.37]
 [ 53724.982]
 [ 53724.983]
 [ 53864.724]
 [ 53882.002]
 [ 53969.248]
 [ 54224.674]
 [ 54225.636]
 [ 54304.474]
 [ 54304.539]
 [ 54366.513]
]

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    Clearly the dummy is being inserted, so I'm a bit confused as to the uninitiated value errors??
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      dummy takes 2 mandatory arguments:
      1. the pdl
      2. the dimension number that will be the dummy dimension
      Somehow, the dimension is defaulting to 0.
      This error should go away if you use 
      $tsearch = $time->dummy(0);

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      which has the same effect and is more explicit
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        Brilliant! Anonymous++
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