Hello, everyone.

I am using Excel 2010. I am working with data which I need to count unique values of one column from the unique values of another column. I have numerically-identified "events" in column A and numerically-identified "patches" in column B.

e.g.,

event patch
001 001
001 002
001 003
002 004
... ...

I want to know how many *unique* patches occur for each *unique* event. Moreover, I want these counts to be printed in a column. In the above example, this would be

event unique patch count
001 3
002 1
... ...

I know that there are formulas to count the total unique values of a single column, but I need to preserve the order of the counts by a second column (events). Thank you in advance for any help!