Mercurial > octave
view scripts/plot/draw/private/__calc_isovalue_from_data__.m @ 23084:ef4d915df748
maint: Merge stable to default.
author | John W. Eaton <jwe@octave.org> |
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date | Mon, 23 Jan 2017 14:27:48 -0500 |
parents | 3a2b891d0b33 e9a0469dedd9 |
children | 092078913d54 |
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## Copyright (C) 2016 Markus Muetzel ## ## 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/>. ## Undocumented internal function. ## -*- texinfo -*- ## @deftypefn {} {@var{isoval} =} __calc_isovalue_from_data__ (@var{data}) ## Calculate a @nospell{"good"} iso value from histogram of data. ## @end deftypefn ## called from isocaps, isosurface function isoval = __calc_isovalue_from_data__ (data) ## use a maximum of 10,000-20,000 samples to limit runtime of hist step = 1; ndata = numel (data); if (ndata > 20_000) step = floor (ndata / 10_000); data = data(1:step:end); ndata = numel (data); endif num_bins = 100; [bin_count, bin_centers] = hist (data(:), num_bins); ## if one of the first two bins contains more than 10 times the count as ## compared to equally distributed data, remove both (zero-padded + noise) if (any (bin_count(1:2) > 10 * (ndata / num_bins))) bin_count(1:2) = []; bin_centers(1:2) = []; endif ## if bins have low counts, remove them (but keep them if we would lose ## more than 90% of bins) bins_to_remove = find (bin_count < max (bin_count)/50); if (length (bins_to_remove) < .9 * num_bins) bin_centers(bins_to_remove) = []; endif ## select middle bar of histogram with previous conditions isoval = bin_centers(floor (numel (bin_centers) / 2)); endfunction