running a function on each cell in a matrix, knowing the index a cell, without using loops
I have a function F that receives an 2D index (i and j) and a constant array C. I want to run this function on each cell in a matrix, meaning - in the (i,j) cell I'll have the value F(i,j,C).
Is there a way to do it in matlab without using loop开发者_高级运维s?
To apply a function to every item in an array or matrix, use arrayfun
.
m = [1:3; 4:6];
arrayfun(@(x) x + 1, m)
To use arrayfun, you need to modify the signature of your function F
so that it takes the item in your matrix at (i,j), not the indicies themselves.
Also, a purely vectorised solution is often faster than using arrayfun
. For example, compare
tic; for(i = 1:1000); mean(m(:)); end; toc
tic; for(i = 1:1000); arrayfun(@mean, m); end; toc
精彩评论