[R] parsing numeric values

[Henrique Dallazuanna]

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
>
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-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O