## Mercurial > hg > octave-max

### view scripts/sparse/spstats.m @ 15489:481417a57a2d

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improve sign and signbit docs
* mappers.cc (Fsign): Note sign (-0) is 0. Add @seealso for signbit.
(Fsignbit): Add @seealso for sign.

author | John W. Eaton <jwe@octave.org> |
---|---|

date | Thu, 04 Oct 2012 10:20:59 -0400 |

parents | 5d3a684236b0 |

children |

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## Copyright (C) 2004-2012 Paul Kienzle ## ## This file is part of Octave. ## ## Octave is free software; you can redistribute it and/or modify it ## under the terms of the GNU General Public License as published by ## the Free Software Foundation; either version 3 of the License, or (at ## your option) any later version. ## ## Octave is distributed in the hope that it will be useful, but ## WITHOUT ANY WARRANTY; without even the implied warranty of ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ## General Public License for more details. ## ## You should have received a copy of the GNU General Public License ## along with Octave; see the file COPYING. If not, see ## <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {[@var{count}, @var{mean}, @var{var}] =} spstats (@var{S}) ## @deftypefnx {Function File} {[@var{count}, @var{mean}, @var{var}] =} spstats (@var{S}, @var{j}) ## Return the stats for the non-zero elements of the sparse matrix @var{S}. ## @var{count} is the number of non-zeros in each column, @var{mean} ## is the mean of the non-zeros in each column, and @var{var} is the ## variance of the non-zeros in each column. ## ## Called with two input arguments, if @var{S} is the data and @var{j} ## is the bin number for the data, compute the stats for each bin. In ## this case, bins can contain data values of zero, whereas with ## @code{spstats (@var{S})} the zeros may disappear. ## @end deftypefn function [count, mean, var] = spstats (S, j) if (nargin < 1 || nargin > 2) print_usage (); endif if (nargin == 1) [i, j, v] = find (S); else v = S; i = 1:length (v); S = sparse (i, j, v); endif [n, m] = size (S); count = sum (sparse (i, j, 1, n, m)); if (nargout > 1) mean = sum (S) ./ count; endif if (nargout > 2) ## FIXME Variance with count = 0 or 1? diff = S - sparse (i, j, mean (j), n, m); var = sum (diff .* diff) ./ (count - 1); endif endfunction %!test %! [n,m,v] = spstats ([1 2 1 2 3 4],[2 2 1 1 1 1]); %! assert (n, sparse ([4,2])); %! assert (m, sparse ([10/4,3/2]), 10*eps); %! assert (v, sparse ([5/3,1/2]), 10*eps);