MATLAB: Matrix calculation indexing conditional

Question

I have a matrxi of 500 rows and 6 columns. I need to sum all the rows of 2nd column of the matrix if their 3rd column and 4th coumns equal to specific numbers.

How can I do that?

Lets explain more: One column is the time. An other column is radius. We can have multiple rows of the same time. Or multiple rows that have the same radius. An other coulmn is number of cells. I want to say for all times=2 and all radius=3 sum the number of cells.

Answer 1

Let A - your array (500 x 6):

T = array2table(A);
T_out = varfun(@sum,T,'InputVariables',2,'GroupingVariables',3:4);