Matrix calculation indexing conditional

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.

[darova]

Do you have any attempts?

[Zeynab Mousavikhamene]

No

Answer 1

[Andrei Bobrov]

Let A - your array (500 x 6):

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

[Zeynab Mousavikhamene]

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.

[Andrei Bobrov]

Please attach small part of your data and result for this part.

[Zeynab Mousavikhamene]

[Zeynab Mousavikhamene]

I want to sum the cell_count for specific time and specific radius. Time is: 1,2,3,4,5,6 and radius is: 1,2,3,4,5

[Andrei Bobrov]

T_out = varfun(@sum,T,'GroupingVariables',...
    {'time','radius'},'InputVariables','cell_count');

[Zeynab Mousavikhamene]

Thanks for the help. T_out is like this:

what is the GroupCount column?

[Andrei Bobrov]

GroupCount this is number of rows - ['time', 'radius'].

[Zeynab Mousavikhamene]

Can you explain more? Because time and radius donot have the same size.

[Andrei Bobrov]

GroupCount this is numbers of the same rows in the sub-matrix of two columns - [time, radius]