Here's one way (assuming your data frame is named dat):
with(dat,
data.frame(a,t(sapply(a,function(x){
apply(dat[a - x >= -5 & a - x <=
0,c('b','c')],2,sum)}))))
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spec...@stat.berkeley.edu
On Tue, 1 Sep 2009, dolar wrote:
Would like some tips on how to avoid loops as I know they are slow in R
i've got a data frame :
a b c
1 5 2
4 6 9
5 2 3
8 3 2
What i'd like is to sum for each value of a, the sum of b and the sum of c
where a equal to or less than (with a distance of 5)
i.e. for row three
we have a=5
i'd like to sum up b and sum up c with the above rule
since 5, 4 and 1 are less than (within a distance of 5) or equal to 5, then
we should get the following result:
a b c
5 13 14
the overall result should be
a b c
1 5 2
4 11 11
5 13 14
8 11 14
how can i do this without a loop?
--
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