nnz

  Signature: (a(N); int+ [o]nnz())

Get number of non-zero values in a PDL $a(); For 1d PDLs, should be equivalent to:

 $nnz = nelem(which($a!=0));

For k>1 dimensional PDLs, projects via number of nonzero elements to N-1 dimensions by computing the number of nonzero elements along the the 1st dimension.

nnz does not process bad values. It will set the bad-value flag of all output ndarrays if the flag is set for any of the input ndarrays.

nnza

  Signature: (a(N); eps(); int+ [o]nnz())

Like nnz() using tolerance constant $eps(). For 1d PDLs, should be equivalent to:

 $nnz = nelem(which(!$a->approx(0,$eps)));

nnza does not process bad values. It will set the bad-value flag of all output ndarrays if the flag is set for any of the input ndarrays.

ccs_encode_pointers

  Signature: (indx ix(Nnz); indx N(); indx [o]ptr(Nplus1); indx [o]ixix(Nnz))

General CCS encoding utility.

Get a compressed storage "pointer" vector $ptr for a dimension of size $N with non-missing values at indices $ix. Also returns a vector $ixix() which may be used as an index for $ix() to align its elements with $ptr() along the compressed dimension.

The induced vector $ix->index($ixix) is guaranteed to be stably sorted along dimension $N():

 \forall $i,$j with 1 <= $i < $j <= $Nnz :
  $ix->index($ixix)->at($i) < $ix->index($ixix)->at($j)   ##-- primary sort on $ix()
 or
  $ixix->at($i)             < $ixix->at($j)               ##-- ... stable

ccs_encode_pointers does not process bad values. It will set the bad-value flag of all output ndarrays if the flag is set for any of the input ndarrays.

ccs_decode_pointer

  Signature: (indx ptr(Nplus1); indx proj(Nproj); indx [o]projix(NnzProj); indx [o]nzix(NnzProj))

General CCS decoding utility.

Project indices $proj() from a compressed storage "pointer" vector $proj(). If unspecified, $proj() defaults to:

 sequence($ptr->dim(0))

ccs_decode_pointer does not process bad values. It will set the bad-value flag of all output ndarrays if the flag is set for any of the input ndarrays.

ccs_pointerlen

  Signature: (ptr(Nplus1); [o]ptrlen(N))

Get number of non-missing values for each axis value from a CCS-encoded offset pointer vector $ptr().

ccs_pointerlen does not process bad values. It will set the bad-value flag of all output ndarrays if the flag is set for any of the input ndarrays.

ccs_xindex1d

  Signature: (which(Ndims,Nnz); a(Na); [o]nzia(NnzA); [o]nnza())

Compute indices $nzai() along dimension "NNz" of $which() whose initial values $which(0,$nzai) match some element of $a(). Appropriate for indexing a sparse encoded PDL with non-missing entries at $which() along the 0th dimension, a la dice_axis(0,$a). $which((0),) and $a() must be both sorted in ascending order.

In list context, returns a list ($nzai,$nnza), where $nnza() is the number of indices found, and $nzai are those "Nnz" indices. In scalar context, trims the output vector $nzai() to $nnza() elements.

ccs_xindex1d does not process bad values. It will set the bad-value flag of all output ndarrays if the flag is set for any of the input ndarrays.

ccs_xindex2d

  Signature: (which(Ndims,Nnz); a(Na); b(Nb); [o]ab(Nab); [o]nab())

Compute indices along dimension "NNz" of $which() corresponding to any combination of values in the Cartesian product of $a() and $b(). Appropriate for indexing a 2d sparse encoded PDL with non-missing entries at $which() via the ND-index piddle $a->slice("*1,")->cat($b)->clump(2)->xchg(0,1), i.e. all pairs $ai,$bi with $ai in $a() and $bi in $b(). $a() and $b() values must be be sorted in ascending order

In list context, returns a list ($ab,$nab), where $nab() is the number of indices found, and $ab are those "Nnz" indices. In scalar context, trims the output vector $ab() to $nab() elements.

ccs_xindex2d does not process bad values. It will set the bad-value flag of all output ndarrays if the flag is set for any of the input ndarrays.

ccs_dump_which

  Signature: (indx which(Ndims,Nnz); SV *HANDLE; char *fmt; char *fsep; char *rsep)

Print a text dump of an index PDL to the filehandle "HANDLE", which default to "STDUT". $fmt is a printf() format to use for output, which defaults to "%d". $fsep and $rsep are field-and record separators, which default to a single space and $/, respectively.

ccs_dump_which does not process bad values. It will set the bad-value flag of all output ndarrays if the flag is set for any of the input ndarrays.

Copyright Policy

Copyright (C) 2007-2022, Bryan Jurish. All rights reserved.

This package is free software, and entirely without warranty. You may redistribute it and/or modify it under the same terms as Perl itself.