Starting with the head of a 499 element matrix whose column names are
now the labels trom a cut() operation, I needed to get to a vector of
midpoints to serve as the basis for plotting a calibration curve
( exp(linear predictor) vs. :
> dput(head(dimnames(mtcal)[2][[1]])) # was starting point
testvec <- c("(-8.616,-3.084]", "(-3.084,-2.876]", "(-2.876,-2.756]",
"(-2.756,-2.668]",
"(-2.668,-2.597]", "(-2.597,-2.539]")
I started this message with the thought of requesting an answer but
kept asking myself if I really had check the docs and tested my
understanding. I eventually solved it using the gsubfn from the gsubfn
package:
testintvl <-as.numeric(gsubfn("\\((-?[[:digit:]]+.?[[:digit:]]*),
(-?[[:digit:]]+.?[[:digit:]]*)\\]",
~ (as.numeric(x)+as.numeric(y))/2, testvec))
# I did discover that carriage returns in the middle of the pattern
will not give desired results, so if this is broken by your mail-
client, be sure to rejoin in the console.
The extra "?"'s after the decimal point are in there because I had 4
NA's around the median linear predictor:
> dimnames(mtcal)[2][[1]][which(is.na(testintvl))]
[1] "(-1.008,-1]" "(-1,-0.9922]" "(0.9914,1]" "(1,1.009]"
So a better test vector would be:
testvec <- c("(-8.616,-3.084]", "(-3.084,-2.876]", "(-2.876,-2.756]",
"(-2.756,-2.668]",
"(-2.668,-2.597]", "(-2.597,-2.539]", "(-1.008,-1]", "(-1,-0.9922]",
"(0.9914,1]", "(1,1.009]" )
> testintvl <-as.numeric(gsubfn("\\((-?[[:digit:]]+.?[[:digit:]]*),(-?
[[:digit:]]+.?[[:digit:]]*)\\]",
+ ~ (as.numeric(x)+as.numeric(y))/2, testvec))
> testintvl
[1] -5.8500 -2.9800 -2.8160 -2.7120 -2.6325 -2.5680 -1.0040 -0.9961
0.9957 1.0045
I offer this to those who may feel regex challenged (as I often do).
The gsubfn function is pretty slick. I don't see an author listed for
the function, but the author of the package documents is Gabor
Grothendieck.
--
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
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.
