Use cellfun instead of for loop

Question

arun 2014-2-28

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/119498-use-cellfun-instead-of-for-loop

评论： arun 2014-2-28

Data.mat

I have a matrix BIGRAMPROB of 10*10*5 cell and i am performing some operation for that i wrote a function. But the problem i am facing is that i want to replace for loop in my code with cellfun and again i want my BIGRAMPROB cell matrix as output. I Have attached a mat file which contain this BIGRAMPROB(10,10,5) cell mat

CODE

function [ BIGRAMPROB ] = Untitled( BIGRAMPROB )
    probmat = BIGRAMPROB(:,:,1); 
    totalnoofvalidbigramunsmoothed = sum(cell2mat(BIGRAMPROB(2:end,1,4))); 
    for i=2:size(BIGRAMPROB,1)  // i want to replace these two for loop with cellfun
       for j=2:size(BIGRAMPROB,2) // i want to replace these two for loop with cellfun
            BIGRAMPROB{i,j,1} = max(BIGRAMPROB{i,j,2}-.75,0)/BIGRAMPROB{i,1,3} + ((.75/BIGRAMPROB{i,1,3})*BIGRAMPROB{i,1,4})*(sum(cell2mat(probmat(2:end,j))>0)/totalnoofvalidbigramunsmoothed); // I want to perform this operation for each cell
         end
       end

This function is calculating the probabilty for each cell in BIGRAMPROB(:,:,1) by using all other value at the place BIGRAMPROB(:,:,2),BIGRAMPROB(:,:,3),BIGRAMPROB(:,:,4)BIGRAMPROB(:,:,5) end

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per isakson 2014-2-28

The attachment is lost and the code is difficult to read.

arun 2014-2-28

I have attached the file......Thanks for taking a look.

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Answer 1

Jos (10584) 2014-2-28

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/119498-use-cellfun-instead-of-for-loop#answer_126509

在 MATLAB Online 中打开

The way to approach this is

create a function that acts on the contents E of a single cell
apply that function to each element of the cell array C using cellfun.

There are various ways to create the function. The function can be a separate code (or m-file). This is useful when it is a difficult function.

function out = Myfunction(E)
x = 1:numel(E) ;
temp = polyfit(x, E(:), 1) ; % example! 
out = (E - polyval(P,x)) ;

and then call it like this

result = cellfun(MyFunction,C)

Another option is to define an inline function, in case it is not too difficult

MyFunction = @(E) E - mean(E(:)) % example!
result = cellfun(@MyFunction,C, 'un',0)

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arun 2014-2-28

First of all thanks for your attention. I got the point and able to implement in both way if the matrix is only 2-d.In my example i am using 3-d matrix and accessing multiple elements. In case of second example you have given how can i calculate the value that is

totalnoofvalidbigramunsmoothed = sum(cell2mat(BIGRAMPROB(2:end,1,4)));
BIGRAMPROB{i,j,1} = max(BIGRAMPROB{i,j,2}-.75,0)/BIGRAMPROB{i,1,3} + ((.75/BIGRAMPROB{i,1,3})*BIGRAMPROB{i,1,4})*(sum(cell2mat(probmat(2:end,j))>0)/totalnoofvalidbigramunsmoothed);
In this case i am not able find the value of i and j
I have attached a mat file of 10*10*5 cell