The fastest is probably to write a PP routine that does it, but it is
easily done using cc8compt (yes, I know it is supposed to be for images,
but it works here too :):
$a = pdl([0,0,1,1,1,0,0,0,0,1,1,1,1,0,0])
$levels = cc8compt($a)
$n_levels = max($levels)
$i_level = which($levels == 1)
$beg=$i_level((0))
$end = $i_level((-1))
for instance. You can of course then return all the begin & end levels
quite easily with a loop:
sub splitit {
my $a = shift;
$levels = cc8compt($a);
$n_levels = max($levels);
my @beg=();
my @end=();
for (my $i=1; $i<=$n_levels; $i++) {
$i_level = which($levels == $i);
push @beg, $i_level((0));
push @end, $i_level((-1));
}
return (pdl(@beg), pdl(@end));
}
Which then gives:
perldl> ($beg, $end) = splitit($a)
perldl> p $beg
[2 9]
perldl> p $end
[4 12]
Hope this helps!
Cheers,
Jarle.
Martin A. Hansen wrote:
> Hello,
>
>
> I have a 1D piddle [0,0,1,1,1,0,0,0,0,1,1,1,1,0,0]
>
> and would like to scan the piddle for the next interval of non-zero
> values given an offset:
>
> ( beg, end ) = scan( pdl, 0 ); # return beg=2, end=4
> ( beg, end ) = scan( pdl, 5 ); # return beg=9, end=12
>
>
> How do you do that with PDL ?
>
>
>
> Martin
>
>
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