[R] sum portions of a vector

[David L Carlson]

How about?

> vec <- 1:10
> breaks <- c(3,8,10)
> g <- cut(vec, c(0, breaks))
> sums <- aggregate(vec, list(g), sum)$x
> nums <- tapply(vec, g, paste0, collapse="+")
> results <- paste0(sums, " = ", nums)
> results
[1] "6 = 1+2+3"      "30 = 4+5+6+7+8" "19 = 9+10"     
 
----------------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77843-4352


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Sam Steingold
> Sent: Monday, December 10, 2012 1:29 PM
> To: r-help at r-project.org
> Subject: [R] sum portions of a vector
> 
> How do I sum portions of a vector into another vector?
> E.g., for
> --8<---------------cut here---------------start------------->8---
> > vec <- 1:10
> > breaks <- c(3,8,10)
> --8<---------------cut here---------------end--------------->8---
> I want to get a vector of length 3 with content
> --8<---------------cut here---------------start------------->8---
> 6 = 1+2+3
> 30 = 4+5+6+7+8
> 19 = 9+10
> --8<---------------cut here---------------end--------------->8---
> Obviously, I could write a loop, but I would rather have a vectorized
> version.
> Thanks!
> 
> --
> Sam Steingold (http://sds.podval.org/) on Ubuntu 12.04 (precise) X
> 11.0.11103000
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