Why Matlab doesn't export the result?

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Dung Le 2016-1-4

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评论： Walter Roberson 2016-1-5

I import an excel file into Matlab. Then I expect with the code I write in Matlab, it will export the result in column 3 in the original excel. But nothing appears in column 3 of the file sample2.xlsx. Could you help me?

clear all
clc
A=xlsread('Criteria.xlsx');
B=xlsread('sample2.xlsx');
n=0;
x=0;
for h=1:99
  if B(h,2)>50
    n=n+1;
    x= x+B(h,3);
  end
end
x=x/n;
for h=1:99
  if B(h,2)>50
    B(h,4)=x;
  end
end
xlswrite('sample2.xlsx',B)

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Image Analyst 2016-1-5

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What is "A" for? You're not even using it.

And column 3 of B has NaNs in it, so x will be a NaN also, which means column 4 is all NaNs. It looks like x is supposed to be the mean of Col 3 of B for rows where B > 50. Is that true? If so, those two for loops can be vectorized:

% Don't read in A - it's not used.
% A=xlsread('Criteria.xlsx');
B=xlsread('sample2.xlsx');  
% Determine which rows to average.
rowsToAverage = B(:,2)>50 & ~isnan(B(:,3));
% Get mean in Column 3
meanOfBigNumbers= mean(B(rowsToAverage, 3));
% Set col 4 = means
B(rowsToAverage, 4) = meanOfBigNumbers;
% Overwrite workbook with new B value.
xlswrite('sample2.xlsx',B)

The xlswrite should work.

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Image Analyst 2016-1-5

Looks like you've found a solution in your parallel thread because you've accepted an answer there. I still claim you don't need all those for loops. But anyway, at least it's working.

Walter Roberson 2016-1-5

Dung Le remarks "Thank you your enthusiastic support :)"

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更多回答（1 个）

Walter Roberson 2016-1-5

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Could you confirm that you want to take the mean of column 3 over the places that column 2 is > 50, and that you want to write copies of that mean to column 4 for those same rows? Like

mask = B(1:99,2) > 50;
x = mean(B(mask,3));
h(mask,4) = x;

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Image Analyst 2016-1-5

The code in my answer (different than Walter's code in this Answer) does work - I actually tried it. There is stuff in all 4 columns. Where you originally had NaN's there will be a blank cell.

Dung Le 2016-1-5