[R] Max within groups
Thomas.Chesney at nottingham.ac.uk
Sat Jul 16 15:55:12 CEST 2011
I know there's a really easy way to do this but I just can't track it down. I experimented with various apply functions but couldn't get it quite right.
I have a matrix like this:
and I'd like to find the max value in Column 2 (or the index to the max value) grouped by the first column. So the max for Group 1, the max for Group 2 etc.
Any help would be appreciated.
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