how can i count number of zeroes in a martix(containing elements 0s and 1s only) which is below any 1s(means in a column top to bottom , if 0 comes then dont count if 1 comes then count whole 0s below that 1.

A(:,:,1) =

     5     7     8
     0     1     9
     4     3     6

A(:,:,2) =

     1     0     4
     3     5     6
     9     8     7

[Stephen23]

What does A have to do with your question? A is not a matrix, and it does not contain only ones and zeros, so it is unclear how it relates to your question.

[ntsh kr]

yes i did a mistake in asking , soory there must be only 0 and 1 but i didnot and in my problem A is a 3d array. thanks

Answer 1

[Stephen23]

>> M = randi(0:1,5,6)
M =
   0   1   1   1   0   1
   0   1   0   0   0   1
   1   0   0   0   1   0
   1   1   1   0   0   1
   0   0   0   1   1   1
>> sum(cumsum(M,1) & M==0, 1)
ans =
   1   2   3   3   1   1

[ntsh kr]

thanks a lot

and if M is a 3d array then how can i?

[Stephen23]

That code will work with 3D arrays.

[ntsh kr]

>> M = randi(0:1,5,6)
M =
   0   1   1   1   0   1;
   0   1   0   0   0   1;
   1   0   0   0   1   0;
   1   1   1   0   0   1;
   0   0   0   1   1   1;
>> sum(cumsum(M,1) & M==0, 1)
ans =
   1   2   3   3   1   1

in this we are opreting along column( i.e direction 1) if we want to operate along row means we want a column vector (1,3,4,2,0) from matrix M then should we do .... sum(cumsum(M,2) &.....) but it is now working then what should we do

[Stephen23]

>> sum(cumsum(M,2) & M==0, 2)
ans =
   1
   3
   4
   2
   0

[ntsh kr]

thank you sir can we learn theory and logic behind sum(cumsum(... &...) command plaese share the link

[Stephen23]

@ntsh kr: read the MATLAB documentation. It is easy to search using any internet search engine. This was the first result returned when I searched for "MATLAB cumsum":

https://www.mathworks.com/help/matlab/ref/cumsum.html