清空筛选条件
清空筛选条件

Operation without for loop

1 次查看（过去 30 天）
Sukuchha
Sukuchha 2012-1-31
I have two matrix.MAtrix A(250000x4)and MAtrix B(250000x4)
I have a function which result a scalar C.
C = myfunction(X,Y);
Now i want to pass each row of MAtrixA and MAtrixB to myfunction without using a for loop.
How to do it ?

请先登录，再回答此问题。

采纳的回答

Andrei Bobrov
Andrei Bobrov 2012-1-31
Y = arrayfun(@(i1)myfunction(A(i1,:), B(i1,:)), 1:size(A,1))
  3 个评论
显示 1更早的评论
Sean de Wolski
Sean de Wolski 2012-1-31
Sure. Permute B so that it is [1x4x250000].
bsxfun(@myFunction,A,permute(B,[3 2 1]));
It's going to use a ton of memory and probably be slower though. Of course, it's still awesomer because it uses bsxfun( :-).
Sukuchha
Sukuchha 2012-1-31
Thanks all for the input, i used andrei method. It seems to be working but havent check its performance of against for loop.

请先登录，再进行评论。

更多回答（1 个）

Walter Roberson
Walter Roberson 2012-1-31
You can make it look prettier using arrayfun(), but arrayfun() is just going to be doing the "for" loop internally.
  4 个评论
显示 2更早的评论
Sukuchha
Sukuchha 2012-1-31
yeh, i wanted something which would be faster than for loop, otherwise i would have done with for loop :)
Walter Roberson
Walter Roberson 2012-1-31
Often in such cases the best thing to do is rewrite the function so that it accepts arrays.
Note that "for" loops are not necessarily slow, especially in new versions. There is probably more overhead in calling myfunction all those times than there is in the "for" loop itself.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Creating and Concatenating Matrices 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by