Initial Commit

octave/shim/histcounts.m

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+function [n, edges] = histcounts (x, edges, varargin)
+  %HISTCOUNTS  Bin counts for explicit edges (MATLAB R2014b+).
+  %
+  %  An owuitools compatibility shim; see contains.m for the policy.
+  %
+  %  Explicit edges only, and that limit is the whole point: MATLAB's
+  %  automatic binning picks the number of bins by a documented but
+  %  non-trivial rule, and a shim that guessed a different one would hand
+  %  back a different histogram without anyone noticing. Called without
+  %  edges, this says so instead.
+  %
+  %  Edge convention, which is where histcounts and the older `histc`
+  %  differ and why this is not a one-line alias: bin i is
+  %  [edges(i), edges(i+1)) and the LAST bin is closed, so a value exactly
+  %  on the final edge lands in the last bin rather than in one of its own.
+
+  if (nargin < 1)
+    error ('histcounts: not enough input arguments');
+  end
+  if (nargin < 2 || ~isnumeric (edges) || isscalar (edges))
+    error (['histcounts: this sandbox supports histcounts(x, edges) with explicit ' ...
+            'edges only. MATLAB''s automatic bin selection is not reproduced here - ' ...
+            'choose the edges, e.g. histcounts(x, linspace(min(x), max(x), 11)), and ' ...
+            'keep whatever form you want in the code you hand over.']);
+  end
+  if (~isempty (varargin))
+    error ('histcounts: this shim takes only (x, edges) - no name/value options');
+  end
+  if (~isnumeric (x) && ~islogical (x))
+    error ('histcounts: x must be numeric');
+  end
+  edges = edges(:).';
+  if (numel (edges) < 2 || any (diff (edges) <= 0))
+    error ('histcounts: edges must be a vector of at least two increasing values');
+  end
+
+  v = double (x(:));
+  v = v(~isnan (v));
+  n = zeros (1, numel (edges) - 1);
+  for i = 1:numel (n)
+    if (i < numel (n))
+      n(i) = sum (v >= edges(i) & v < edges(i + 1));
+    else
+      n(i) = sum (v >= edges(i) & v <= edges(i + 1));
+    end
+  end
+end