On Dec 10, 2012, at 11:29 AM, Sam Steingold wrote:
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.
> split(vec, findInterval(seq_along(vec), breaks+.001, right=TRUE) )
$`0`
[1] 1 2 3
$`1`
[1] 4 5 6 7 8
$`2`
[1] 9 10
Needed to push the breaks slightly rightward since findInterval
generally returns left-closed interval values.
--
David Winsemius
Alameda, CA, USA
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