All,
I'm curious from a speed perspective what the analog of apply is in data.table
as I have a problem where, for each row, I want to take either the min or the
max of several columns depending upon the value of a third column:
For example:
test.dt <- data.table(ID=1:10, SCORE_1=rnorm(10), SCORE_2=rnorm(10),
SCORE_3=rnorm(10), MAX_OR_MIN=c(rep("Max", 5), rep("Min", 5)))
For each row I'd like to get the max of SCORE_1, SCORE_2, and SCORE_3 if the
MAX_OR_MIN value is MAX and the min of SCORE_1, SCORE_2, and SCORE_3 if the
MAX_OR_MIN value is MIN.
It isn't too difficult to come up with a "bulky" and slow solution, but I'm
wondering if I'm missing a way in which data.table would make such an effort
elegant and quick.
Any help greatly appreciated.
Damian Betebenner
Center for Assessment
PO Box 351
Dover, NH 03821-0351
Phone (office): (603) 516-7900
Phone (cell): (857) 234-2474
Fax: (603) 516-7910
[email protected]<mailto:[email protected]>
www.nciea.org<http://www.nciea.org/>
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