4 messages · Stefan Fritsch, Chuck Cleland, Douglas Bates +1 more
Dear R Users, I want to exclude elements in a vector by: vector[-exclude] is it intended to cause an error if no elements are excluded?
vector <- 1:10 exclude <- NULL vector[-exclude]
Error in -exclude or am I just definig exclude wrong, if no elements should be excluded? with kind regards, Stefan Fritsch
Dear R Users, I want to exclude elements in a vector by: vector[-exclude] is it intended to cause an error if no elements are excluded?
vector <- 1:10 exclude <- NULL vector[-exclude]
Error in -exclude or am I just definig exclude wrong, if no elements should be excluded?
One approach would be to set "exclude" to a number greater than the
length of the vector:
x <- 1:10
exclude <- length(x) + 1
x[-exclude]
[1] 1 2 3 4 5 6 7 8 9 10
library(fortunes)
fortune("dog")
Firstly, don't call your matrix 'matrix'. Would you call your dog 'dog'?
Anyway, it might clash with the function 'matrix'.
-- Barry Rowlingson
R-help (October 2004)
with kind regards, Stefan Fritsch
______________________________________________ R-help at 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.
Chuck Cleland, Ph.D. NDRI, Inc. (www.ndri.org) 71 West 23rd Street, 8th floor New York, NY 10010 tel: (212) 845-4495 (Tu, Th) tel: (732) 512-0171 (M, W, F) fax: (917) 438-0894
On 9/25/2008 7:43 AM, Stefan Fritsch wrote:
Dear R Users, I want to exclude elements in a vector by: vector[-exclude] is it intended to cause an error if no elements are excluded?
vector <- 1:10 exclude <- NULL vector[-exclude]
Error in -exclude or am I just definig exclude wrong, if no elements should be excluded?
Yes. I'm not sure what you want to do can be done in a clean way. The problem is with the semantics of the indexing operator for numeric indices. A "natural" way of expressing the empty numeric vector is numeric(0) When you use a numeric vector as a set of indices the first check is to determine if all the values are negative, in which case the indices are used to exclude rather than include. However, you can't tell whether the elements of the empty numeric vector are positive or negative because there aren't any elements. Thus vector[numeric(0)] is the same as vector[-numeric(0)]
(1:10)[numeric(0)]
integer(0)
(1:10)[-numeric(0)]
integer(0) The error message you were getting results from the class of NULL, which is different from the class of numeric(0). Arithmetic operations are defined, to some extent, for numeric(0) but not for NULL.
One approach would be to set "exclude" to a number greater than the
length of the vector:
x <- 1:10
exclude <- length(x) + 1
x[-exclude]
[1] 1 2 3 4 5 6 7 8 9 10
library(fortunes)
fortune("dog")
Firstly, don't call your matrix 'matrix'. Would you call your dog 'dog'?
Anyway, it might clash with the function 'matrix'.
-- Barry Rowlingson
R-help (October 2004)
with kind regards, Stefan Fritsch
______________________________________________ R-help at 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.
-- Chuck Cleland, Ph.D. NDRI, Inc. (www.ndri.org) 71 West 23rd Street, 8th floor New York, NY 10010 tel: (212) 845-4495 (Tu, Th) tel: (732) 512-0171 (M, W, F) fax: (917) 438-0894
______________________________________________ R-help at 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.
Try this: vector[ setdiff(seq_along(vector), as.numeric(idx)) ] where idx is your vector of indices to exclude, e.g. idx <- 3:4 idx <- numeric(0) idx <- NULL The last one gets converted to numeric(0) by as.numeric so it still works. On Thu, Sep 25, 2008 at 7:43 AM, Stefan Fritsch
Dear R Users, I want to exclude elements in a vector by: vector[-exclude] is it intended to cause an error if no elements are excluded?
vector <- 1:10 exclude <- NULL vector[-exclude]
Error in -exclude or am I just definig exclude wrong, if no elements should be excluded? with kind regards, Stefan Fritsch
______________________________________________ R-help at 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.