I have a matrix that is (110500*4); the First column are identiers/IDs, these values are not unique, meaning same value can appear more than once. I need to find out how many times each ID appears then basically aggregate the matrix based on these unique IDs to where 1st column is: Unique IDs, 2nd, 3rd and 4th : Sum of elements from original table associated with unique ID. Example:
A=[5 12 25 0 2 10 24 0 1 7 25 1 5 5 12 0 2 6 23 1];
then end matrix should have only 3 rows (unique values are 5,2 & 1) with 1st column: unique values, 2nd column : Sum of values associated with unique ID (5) from column 2, and same for the next 2 columns. basically, reduce the matrix to unique ID then aggregate the next columns based on that.
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