If you skip the index part using where does it work?
E.g.,
$a->where($a==0) .= 1;
$b = $b->where($b>0)->sever;
--Chris
On 1/12/2018 20:07, Trevor Carey-Smith wrote:
Thanks Craig.
In the interim, is there a better way to do the following:
$a(which($a==0)).=1;
$b = $b(which($b > 0))->sever;
as now I'll have to replace all this sort of thing with something like:
$tmp=which($a==0);
if ($tmp->nelem > 0) { a($tmp) .= 1; }
$tmp = which($b > 0);
if ($tmp->nelem > 0) {
$b = $b($tmp)->sever;
} else {
$b = pdl([ ]);
}
Cheers,
Trevor
________________________________________
From: Craig DeForest <[email protected]>
Sent: Saturday, 13 January 2018 9:35 a.m.
To: Trevor Carey-Smith
Cc: Craig DeForest; [email protected]
Subject: Re: [Pdl-general] Slicing pdl with empty index variable
Hmmm. Looks like you’ve discovered a wart. Indexing pdl(1,2) with an Empty
does the right thing and returns Empty. But indexing a scalar or a 1-D PDL
with one element fails. I think it’s because Empties are implemented under the
hood as 1x0 PDLs (to distinguish them from Nulls, which have 0 in the first
position).
On Jan 11, 2018, at 8:52 PM, Trevor Carey-Smith <[email protected]>
wrote:
Hi,
Sorry I've been out of the PDL loop for a long time, but have an old script
written in PDL that I use a lot. After a recent IT upgrade here we have shifted
to PDL v2.018 and I'm getting some behaviour that is new from our previous
install (2.4 in the old numbering system???).
The script uses some which() statements to create indexing vectors to slice the
original pdl. Normally when the which statement comes back empty, the slice
command returns an empty pdl itself. But if the slicing dimension (regardless
of the total number of dimensions) of the original pdl is of length 1 bad
things happen. Perhaps an example is clearer:
pdl> p $empty=pdl([])
Empty[0]
pdl> p $d2=pdl([1,2])
[1 2]
pdl> p $d2($empty)
Empty[0]
pdl> p $d1=pdl([1])
[1]
pdl> p $d1($empty)
Stringizing problem: slice: slice starts out of bounds in pos 0 (start is 1;
source dim 0 runs 0 to 0). eval {...} called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/lib/perl5/site_perl/5.24.1/x86_64-linux-thread-multi/PDL/Core.pm
line 2857
PDL::string(PDL=SCALAR(0x1053d10), undef, "") called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 402
main::p(PDL=SCALAR(0x1053d10)) called at (eval 151) line 4
main::__ANON__() called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 719
eval {...} called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 719
main::eval_and_report("p \$d1->slice(\$empty)\x{a}") called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 655
main::process_input() called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 675
eval {...} called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 675
at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/lib/perl5/site_perl/5.24.1/x86_64-linux-thread-multi/PDL/Core.pm
line 2888, <STDIN> line 92.
PDL::string(PDL=SCALAR(0x1053d10), undef, "") called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 402
main::p(PDL=SCALAR(0x1053d10)) called at (eval 151) line 4
main::__ANON__() called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 719
eval {...} called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 719
main::eval_and_report("p \$d1->slice(\$empty)\x{a}") called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 655
main::process_input() called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 675
eval {...} called at
/scale_akl_persistent/filesets/opt_niwa/centos7-x86_64-skl_prelim/GCC-4.8.5/Perl/5.24.1-GCC-4.8.5/bin/perldl
line 675
Can anyone shed any light on what's going on here??
Thanks,
Trevor.
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