Threading part of a function over each element in a cell array

Hi,

I would like to thread part of a function over each element in a cell array. I'm afraid I'm being totally non-descriptive, so let me give an example.

Suppose I have a cell array, with each cell containing a 1 by 2 vector:

mycellarray={[1 2],[3 4],[5 6]};

I have a function, which I will call myfun. myfun takes three arguments:

myfun(a,b,c)

where a, b, and c are scalars. Let n be some scalar, say n=9. I wish to evaluate the function myfun with a=n and with b and c taking the values given in the 1 by 2 vectors contained in mycellarray. So, I would like the result to be:

{myfun(i,1,2),myfun(i,3,4),myfun(i,5,6)}

In other words, I want, in a sense, to "thread" myfun over mycellarray, which contains the values of b and c.

Is there a way to do this that might be faster, or more elegant in terms of the code, than the following (that is, using a "for" loop):

mycellarray={[1 2],[3 4],[5 6]};
n=9;

newarray=zeros(1,length(mycellarray));

for i=1:length(mycellarray)
    newarray(i)=myfun(n,mycellarray{i}(1),mycellarray{i}(2));
end

Thank you very much for your time!

Andrew DeYoung

Carnegie Mellon University

Answer 1

[Sean de Wolski]

The for-loop is probably the fastest way. You could also do:

newarray = cellfun(@(C)myfun(n,C(1),C(2)),mycellarray)

But I've found cellfun to always be slower than a well constructed for-loop. It might be different on your machine/version.