How to find the location of the first cell which contains a specific value in an array?

I have an array, all the cells are either with value 0 or value 1.

For each row, I need to find the location in form of (row, column) for the fist cell with value 1 in this row, and the location for the last cell with value 1 in this same row.

Then I will repeat this to all the other rows of the matrix.

I used double for loop, but I did succeed in storing the cell locations.

Can anyone help me?

Thank you.

Answer 1

[per isakson]

I'm not sure what you mean by "cell". Hint:

    m = randi( [0,1], [12,12] );
    n = nan( 2, 12 );

    for jj = 1 : size( m, 2 )
        n(:,jj) = [ find( m(:,jj)==1, 1, 'first' )
                    find( m(:,jj)==1, 1, 'last'  ) ];
    end

I'm not sure how it behaves if there is no value, 1, in a column.

[zy]

cell is just the single matrix, such as for a 10x10 matrix M, M(1,2) is a cell

[Guillaume]

The proper name is element. Your usage of cell is confusing because matlab also has a data structure called cell array, whose syntax is slightly different to that of a matrix.

[per isakson]

Thus, the code behaves as you require(?). However, you didn't say what should be returned for columns, which don't include any 1.

[Image Analyst]

Guillaume's right. zy, please please read the FAQ on cells so that you don't confuse the terminology again: http://matlab.wikia.com/wiki/FAQ#What_is_a_cell_array.3F It makes a tremendous difference in how the code is built. Cell arrays are a lot more complicated than simple numerical arrays - you gotta pay for that extra flexibility. Avoid them if possible.

[zy]

Ok, I will read the FAQ for better understanding of those terminologies, thank you.

[zy]

Yes, per Isakson, it works, thank you very much. It helps me a lot.