How to select certain columns of a matrix only when the first two rows always show 1 and the other two rows a 0?

Hi everybody!

I have a Matrix with 4 rows and 922 columns M(4,2300) containing ones and zeros as shown below

1	0	1	1  ...
1	0	1	1  ...
0	0	0	1  ...
0	0	0	0  ...

I want to keep only the columns when the first two rows show a 1 and row three and four show a zero.

In the example above column 1 and 3 fulfill the conditions whereas column 2 and 4 don't.

Does somebody have a nice idea to write a simple code to extract the columns to have an output for the example above like: [1 0 1 0]?

Thanks a lot for your help guys!!!

Answer 1

[Jalaj Gambhir]

Hi,

Use:

col = find(all(matrix(1:4,:)==[1;1;0;0]))

This will give you all the columns that satisfy this condition. You can then use

matrix(:,col)

to extract those columns from the matrix.

Hope this helps!

[Kim Arnold]

Thanks for your answer :)

I did it with find(all(matrix(1:2,:)==1 & matrix(3:4,:)==0)); which is basically the same as you did :)