On Aug 29, 2010, at 8:47 PM, Lorenzo Cattarino wrote:
Hi,
I have the following matrix
cc <- matrix (1:21, 3)
cc[,3:4]<- 0
cc
[,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,] 1 4 0 0 13 16 19
[2,] 2 5 0 0 14 17 20
[3,] 3 6 0 0 15 18 21
and I would like to sum just the values in columns 2, 3 and 4, so to
have something like
1 4 13 16 19
2 5 14 17 20
3 6 15 18 21
To take only selected columns:
> CC <-cc[,c(1,2,5,6,7)]
> CC
[,1] [,2] [,3] [,4] [,5]
[1,] 1 4 13 16 19
[2,] 2 5 14 17 20
[3,] 3 6 15 18 21
I'm having difficulty understanding the point of summing columns which
you have just set to zero so am taking the liberty of changing the
task to summing columns 2-4 and leaving in column 2 of the shortened
matrix:
> CC[,2] <-apply(cc[ , 2:4], 1, sum)
> CC
[,1] [,2] [,3] [,4] [,5]
[1,] 1 21 13 16 19
[2,] 2 24 14 17 20
[3,] 3 27 15 18 21
Thanks
Lorenzo
[[alternative HTML version deleted]]
______________________________________________
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.
