## How to change an entire column.

on 29 Apr 2013

### Iman Ansari (view profile)

Hi,

I have a matrix with a dimension of 10x640. The matrix is filled with ones and zeros. If there is a zero in one of columns, I want the entire column to be zeros. How can I do this?

Example:

```[[1,0,1];[1,1,1]]
```

Output should be:

```[[1,0,1];[1,0,1]]
```

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### Iman Ansari (view profile)

on 29 Apr 2013
``` A = randi(10,[10 640])-1;
B = A;
B(:,sum(A==0)>0)=0;```

Jan Simon

### Jan Simon (view profile)

on 29 Apr 2013

any(A, 2) is faster than sum(A==0)>0.

### Image Analyst (view profile)

on 29 Apr 2013

Try this:

```% Make sample data.
A = ones(10, 640);
% Stick a zero in columns 3, and 5.
A(9, 3) = 0;
A(8, 5) = 0
```
```% Now that we have some sample data, do what Anton wants.
% Find out which columns have zeros in them
columnsWithZeros = any(~A);  % Assumes A is only 0's and 1's.
A(:, columnsWithZeros) = 0; % Set whole column(s) to zero.
```

Image Analyst

### Image Analyst (view profile)

on 29 Apr 2013

If you want a terse "one-liner" you can do this:

```A(:, any(~A)) = 0;
```

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