parsing numeric values

library(gsubfn)

source("http://gsubfn.googlecode.com/svn/trunk/R/gsubfn.R")
strapply("test", as.numeric)

Thanks a lot, both of you.

Incidentally, I made R crash when I forgot the X argument to strapply,

library(gsubfn)
Loading required package: tcltk
Loading Tcl/Tk interface ... done
strapply("test", as.numeric)

?*** caught bus error ***
address 0x13c, cause 'non-existent physical address'

Traceback:
?1: .External("dotTclcallback", ..., PACKAGE = "tcltk")
?2: .Tcl.callback(x, e)
?3: makeAtomicCallback(x, e)
?4: makeCallback(get("value", envir = ref), get("envir", envir = ref))
?5: FUN(X[[3L]], ...)
?6: lapply(val, val2obj)
?7: .Tcl.args.objv(...)
?8: structure(.External("dotTclObjv", objv, PACKAGE = "tcltk"), class
= "tclObj")
?9: .Tcl.objv(.Tcl.args.objv(...))
10: tcl("set", "e", e)
11: strapply1(x, pattern, backref, ignore.case)
12: FUN("test"[[1L]], ...)
13: lapply(X, FUN, ...)
14: sapply(X, ff, simplify = is.logical(simplify) && simplify,
USE.NAMES = USE.NAMES)
15: strapply("test", as.numeric)

Possible actions:
1: abort (with core dump, if enabled)
2: normal R exit
3: exit R without saving workspace
4: exit R saving workspace

sessionInfo()
R version 2.10.0 (2009-10-26)
i386-apple-darwin9.8.0

locale:
[1] en_GB.UTF-8/en_GB.UTF-8/C/C/en_GB.UTF-8/en_GB.UTF-8

attached base packages:
[1] stats ? ? graphics ?grDevices utils ? ? datasets ?grid ? ? ?methods
[8] base

other attached packages:
[1] ggplot2_0.8.3 ?reshape_0.8.3 ?plyr_0.1.9 ? ? proto_0.3-8 ? ?fortunes_1.3-6

2009/11/18 Gabor Grothendieck <ggrothendieck at gmail.com>:

A minor variant might be the following:

? library(gsubfn)
? strapply(input, "\\d+\\.\\d+E[-+]?\\d+", as.numeric, simplify = rbind)

where:

- as.numeric is used in place of c in which case we do not need combine
- \\d+ matches one or more digits
- \\. matches a decimal point
- [-+]? matches -, + or nothing (i.e. an optional sign).
- parentheses around the regular expression not needed

On Wed, Nov 18, 2009 at 7:28 AM, Henrique Dallazuanna <wwwhsd at gmail.com> wrote:

Try this:

strapply(input, "([0-9]+\\.[0-9]+E-[0-9]+)", c, simplify = rbind,
combine = as.numeric)

On Wed, Nov 18, 2009 at 9:57 AM, baptiste auguie
<baptiste.auguie at googlemail.com> wrote:

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

--
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O