Another advantage of the apply family of functions is that
they determine the size and type of their output in an
efficient way, which is sometimes tricky when you write
the loop yourself.
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spec...@stat.berkeley.edu
On Wed, 2 Sep 2009, Alexander Shenkin wrote:
Though, from my limited understanding, the 'apply' family of functions
are actually just loops. Please correct me if I'm wrong. So, while
more readable (which is important), they're not necessarily more
efficient than explicit 'for' loops.
allie
On 9/2/2009 3:13 AM, Phil Spector wrote:
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?
--
View this message in context:
http://www.nabble.com/Avoiding-loops-tp25251376p25251376.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
