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changeset 28902:69bd3e52d0b8

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spy.m: Overhaul function. * spy.m: Rewrite documentation on optional arguments. Add input validation for maximum number of inputs. Use for loop directly over varargin rather than over length (varargin). Don't capture third output from find() which is never used. Add xlabel to bottom of plot reporting the number of non-zero elements. Add BIST tests for input validation.
author Rik <rik@octave.org>
date Tue, 13 Oct 2020 11:48:30 -0700
parents 3c37ae43996a
children 614a23ddba7a
files scripts/sparse/spy.m
diffstat 1 files changed, 18 insertions(+), 15 deletions(-) [+]
line wrap: on
line diff
--- a/scripts/sparse/spy.m	Tue Oct 13 11:36:33 2020 -0700
+++ b/scripts/sparse/spy.m	Tue Oct 13 11:48:30 2020 -0700
@@ -29,17 +29,17 @@
 ## @deftypefnx {} {} spy (@dots{}, @var{line_spec})
 ## Plot the sparsity pattern of the sparse matrix @var{x}.
 ##
-## If the argument @var{markersize} is given as a scalar value, it is used to
-## determine the point size in the plot.
+## If the optional numeric argument @var{markersize} is given, it determines
+## the size of the markers used in the plot.
 ##
-## If the string @var{line_spec} is given it is passed to @code{plot} and
-## determines the appearance of the plot.
+## If the optional string @var{line_spec} is given it is passed to @code{plot}
+## and determines the appearance of the plot.
 ## @seealso{plot, gplot}
 ## @end deftypefn
 
 function spy (x, varargin)
 
-  if (nargin < 1)
+  if (nargin < 1 || nargin > 3)
     print_usage ();
   endif
 
@@ -49,21 +49,22 @@
   else
     line_spec = ".";
   endif
-  for i = 1:length (varargin)
-    if (ischar (varargin{i}))
-      if (length (varargin{i}) == 1)
-        line_spec = [line_spec, varargin{i}];
+  for arg = varargin
+    arg = arg{1};
+    if (ischar (arg))
+      if (numel (arg) == 1)
+        line_spec = [line_spec, arg];
       else
-        line_spec = varargin{i};
+        line_spec = arg;
       endif
-    elseif (isscalar (varargin{i}))
-      markersize = varargin{i};
+    elseif (isreal (arg) && isscalar (arg))
+      markersize = arg;
     else
       error ("spy: expected markersize or linespec");
     endif
   endfor
 
-  [i, j, s] = find (x);
+  [i, j] = find (x);
   [m, n] = size (x);
 
   if (isnan (markersize))
@@ -73,6 +74,7 @@
   endif
 
   axis ([0, n+1, 0, m+1], "ij");
+  xlabel (sprintf ("nnz = %d", nnz (x)));
 
 endfunction
 
@@ -81,5 +83,6 @@
 %! clf;
 %! spy (sprand (10,10, 0.2));
 
-## Mark graphical function as tested by demo block
-%!assert (1)
+## Test input validation
+%!error <Invalid call> spy ()
+%!error <Invalid call> spy (1,2,3,4)