[R] Strange (non-deterministic) problem with strsplit
Henrik Bengtsson
hb at maths.lth.se
Sat Jul 17 01:59:17 CEST 2004
[Moving this thread to R-devel instead]
I suspect your "random" results are due to a bug in gsub(). On my R v1.9.0
(Rterm and Rgui) R crashes when I do
% R --vanilla
> gsub(" ", "", "abb + c | a*b", perl=TRUE)
Trying
> gsub(" ", "", "b c + d | a * b", perl=TRUE)
and I'll get NULL. With
> gsub("\\s", "", "bc + d | a * b", perl=TRUE)
it works as expected. So there is something buggy for sure.
This might have been fixed in R v1.9.1 or its patched version. (I'm still
busy to recover from a HDD crash, but, yes, I will update to Rv1.9.1. BTW,
what's the name of the error logger for Windows that is once in a while
recommended on this list and that gives more detailed errors than the
default Windows one?)
Cheers
Henrik
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of hadley wickham
> Sent: Friday, July 16, 2004 10:50 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Strange (non-deterministic) problem with strsplit
>
>
> I'm having an odd problem with strsplit (well I think it's
> strplit that's causing the problem). When I run the code
> below as follows: str(parseFormulaMin(y +x +d ~ b +d +e| a * b))
>
> I expect to get
> List of 3
> $ y: chr "y+x+d"
> $ x: chr "b+d+e"
> $ g: chr "a*b"
>
> But about half the time I get
>
> List of 3
> $ y: chr "y+x+d"
> $ x: chr "b+d+e"
> $ g: chr "a*[square box]"
> (square box not reproduced here because copy and pasting it
> seems to break my web mail)
>
> Can anyone reproduce the problem and/or suggest any solutions?
>
> parseFormula <- function(formula) {
> splitvars <- function(x) {
> strsplit(x, "\\+|\\*")[[1]]
> }
> stripwhitespace <- function(x) {
> gsub("\\s", "", x, perl=T)
> }
>
> vars <- stripwhitespace(as.character(formula)[3])
> varsplit <- strsplit(vars, "|", fixed=TRUE)[[1]]
>
> parts <- list(
> y = stripwhitespace(as.character(formula)[2]),
> x = varsplit[1],
> g = varsplit[2]
> )
> lapply(parts, splitvars)
> }
>
> Thanks,
>
> Hadley
>
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