Number of zeros in a matrix

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Bob Choy
Bob Choy 2012-11-17
I need to create a function where I have a matrix and the function returns the number of zeros in that matrix. I need to do this using the if condition.
Then write in a .txt file which columns had more than 12 zeros.
Can someone help me out with this?
Thank you very much.
  2 个评论
Azzi Abdelmalek
Azzi Abdelmalek 2012-11-17
Why did you need to do it with if condition?
Bob Choy
Bob Choy 2012-11-17
Because thats what I usually work with but if thats impossible nevermind it.

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采纳的回答

Matt Fig
Matt Fig 2012-11-17
编辑：Matt Fig 2012-11-17
The number of zeros in the matrix A is:
sum(~A(:))
So we can make this a function:
f = @(x) sum(~x(:));
Now test it:
x = [1 2 3;0 0 0;3 0 9]
f(x)
  5 个评论
显示 3更早的评论
Matt Fig
Matt Fig 2012-11-18
M = [1 0 1 1;1 1 1 0]
fid = fopen('mytext.txt','wt')
fprintf(fid,'%i ',find(sum(~M) >= 1))
fclose(fid)
Bob Choy
Bob Choy 2012-11-18
Thank you so much! Keep up the good work, cheers!

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更多回答（2 个）

Andrei Bobrov
Andrei Bobrov 2012-11-17
a - your matrix
number_columns = find(sum(~a) > 12);
Walter Roberson
Walter Roberson 2012-11-18
numel(M) - nnz(M)

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