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matlabmatrixoctavescientific-computing

Use if clause in arrayfun in Octave/Matlab

Is it possible to use "if" in arrayfun like the following in Octave?

a = [ 1 2; 3 4];
arrayfun(@(x) if x>=2 1 else 0 end,  a)

And Octave complains:

>>> arrayfun(@(x) if x>=2 1 else 0 end, a)
                                     ^

Is if clause allowed in arrayfun?

Solution

  • In Octave you can't use if/else statements in an inline or anonymous function in the normal way. You can define your function in it's own file or as a subfunction like this:

    function a = testIf(x)
     if x>=2
        a = 1;
     else 
        a = 0;
     end
 end

    and call arrayfun like this: 

    arrayfun(@testIf,a)
ans =

   0   1
   1   1

    Or you can use this work around with an inline function: 

    iif = @(varargin) varargin{2 * find([varargin{1:2:end}], 1, ...
                                     'first')}();

arrayfun(iif, a >= 2, 1, true, 0)
ans =

   0   1
   1   1

    There's more information here.