Hi Carol,
On 07/21/2014 01:33 PM, carol white wrote:
Might be a trivial question but how to identify the odd and even indices of a
vector?
x = c(1,z,w,2,6,7)
el of odd indices= 1,w,6
el of even indices= z,2,7
The easiest way is to subset your vector with c(TRUE, FALSE) to keep
only the odd indices:
> letters[c(TRUE, FALSE)]
[1] "a" "c" "e" "g" "i" "k" "m" "o" "q" "s" "u" "w" "y"
and with c(FALSE, TRUE) to keep only the even indices:
> letters[c(FALSE, TRUE)]
[1] "b" "d" "f" "h" "j" "l" "n" "p" "r" "t" "v" "x" "z"
Note that the above doesn't work properly with vector of length < 2.
A method that works independently of the length of the vector (using
the is.odd and is.even functions from the "identifying odd or even
number" post that you referred to):
x[is.odd(seq_along(x))]
x[is.even(seq_along(x))]
Hope this helps,
H.
given the def of odd and even in
https://stat.ethz.ch/pipermail/r-help/2010-July/244299.html
should a loop be used?
for (i in 1: length(x))
if (is.odd(i)) print (i)
Carol
[[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.
--
Hervé Pagès
Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024
E-mail: hpa...@fhcrc.org
Phone: (206) 667-5791
Fax: (206) 667-1319
______________________________________________
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.
