Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / miscellaneous-1.1.0 / match.m

diff --git a/octave_packages/miscellaneous-1.1.0/match.m b/octave_packages/miscellaneous-1.1.0/match.m
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+## Copyright (C) 2007 Muthiah Annamalai <muthiah.annamalai@mavs.uta.edu>
+## Copyright (C) 2012 Carnë Draug <carandraug+dev@gmail.com>
+##
+## This program 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.
+##
+## This program 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
+## this program; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File}  @var{result} = {} match ( @var{fun_handle}, @var{iterable} )
+## match is filter, like Lisp's ( & numerous other language's ) function for
+## Python has a built-in filter function which takes two arguments,
+## a function and a list, and returns a list. 'match' performs the same
+## operation like filter in Python. The match applies the
+## function to each of the element in the @var{iterable} and collects
+## that the result of a function applied to each of the data structure's
+## elements in turn, and the return values are collected as a list of 
+## input arguments, whenever the function-result is 'true' in Octave
+## sense. Anything (1,true,?) evaluating to true, the argument is
+## saved into the return value.
+##
+## @var{fun_handle} can either be a function name string or a
+## function handle (recommended).
+## 
+## Typically you can use it as,
+## @example
+## match(@@(x) ( x >= 1 ), [-1 0 1 2])
+##       @result{}   1   2
+## @end example
+## @seealso{reduce, cellfun, arrayfun, cellfun, structfun, spfun}
+## @end deftypefn
+
+function rval = match (fun_handle, data)
+
+  if (nargin != 2)
+    print_usage;
+  endif
+
+  if (isa (fun_handle, "function_handle"))
+    ##do nothing
+  elseif (ischar (fun_handle))
+    fun_handle = str2func (fun_handle);
+  else
+    error ("fun_handle must either be a function handle or the name of a function");
+  endif
+
+  LD   = length(data);
+
+  if (iscell (data))
+    rval = {};
+    for idx=1:LD
+      if fun_handle(data{idx}), rval = [rval, data{idx}]; endif
+    endfor
+  elseif (ismatrix (data))
+    rval = [];
+    for idx=1:LD
+      if fun_handle(data(idx)), rval = [rval, data(idx)]; endif
+    endfor
+  else
+    error("data must either be a cell array or matrix");
+  endif
+endfunction
+
+%!assert(match(@(x) mod(x,2),1:10),[1:2:10],0)
+%!assert(match(@sin,1:10),[1:10],0)
+%!assert(match(@(x) strcmp('Octave',x),{'Matlab','Octave'}),{'Octave'},0)
+%!assert(match(@(x) (x>0), [-10:+10]),[1:10],0)