It only works if "some text" at the beginning has no digits, dots, E characters or sign characters.
On Wed, Nov 18, 2009 at 12:44 PM, Bert Gunter <gunter.ber...@gene.com> wrote: > The previous elegant solutions required the use of the gsubfn package. > Nothing wrong with that, of course, but I'm always curious whether still > relatively simple base R solutions can be found, as they are often (but not > always!) much faster. And anyway, it seems to be in the spirit of your query > to try such a solution. So here is one base R approach that I believe works. > I'll break it up into 2 lines so you can see what's going on. > > ## Using your example... > ## First replace everything but the number with spaces > >> z <- gsub("[^[:digit:]E.+-]"," ",input) >> z > [1] " " > [2] " 1.3770E-03 3.4644E-07" > [3] " 1.9412E-04 4.8840E-08" > [4] "" > [5] " " > [6] " 1.3770E-03 3.4644E-07" > [7] " 1.9412E-04 4.8840E-08" > > ## Now it can be scanned to a numeric via > >> z<-scan(textConnection(z),what=0) > Read 8 items >> z > [1] 1.3770e-03 3.4644e-07 1.9412e-04 4.8840e-08 1.3770e-03 3.4644e-07 > 1.9412e-04 4.8840e-08 > > ######## > I believe this strategy is reasonably general, but I haven't checked it > carefully and would appreciate folks pointing out where it trips up (e.g. > perhaps with NA's). > > Best, > > Bert Gunter > Genentech Nonclinical Biostatistics > > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On > Behalf Of baptiste auguie > Sent: Wednesday, November 18, 2009 3:57 AM > To: r-help > Subject: [R] parsing numeric values > > Dear list, > > I'm seeking advice to extract some numeric values from a log file > created by an external program. Consider the following example, > > input <- > readLines(textConnection( > "some text > <ax> = 1.3770E-03 <bx> = 3.4644E-07 > <ay> = 1.9412E-04 <by> = 4.8840E-08 > > other text > <aax> = 1.3770E-03 <bbx> = 3.4644E-07 > <aay> = 1.9412E-04 <bby> = 4.8840E-08")) > > ## this is what I want > results <- c(as.numeric(strsplit(grep("<ax>", input,val=T), " ")[[1]][8]), > as.numeric(strsplit(grep("<ay>", input,val=T), " ")[[1]][8]), > as.numeric(strsplit(grep("<aax>", input,val=T), " ")[[1]][9]), > as.numeric(strsplit(grep("<aay>", input,val=T), " ")[[1]][9]) > ) > > ## [1] 0.00137700 0.00019412 0.00137700 0.00019412 > > The use of strsplit is not ideal here as there is a different number > of space characters in the lines containing <ax> and <aax> for > instance (hence the indices 8 and 9 respectively). > > I tried to use gsubfn for a cleaner construct, > > strapply(input, "<ax> += +([0-9.]+)", c, simplify=rbind,combine=as.numeric) > > but I can't seem to find the correct regular expression to deal with > the exponent. > > > Any tips are welcome! > > > Best regards, > > baptiste > > ______________________________________________ > 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. > > ______________________________________________ > 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. > ______________________________________________ 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.