Re: [R] Converting characters to numbers in data frames

From: Sundar Dorai-Raj <sundar.dorai-raj_at_pdf.com>
Date: Thu 25 Aug 2005 - 22:08:35 EST

Anon. wrote:
> I'm sure I'm missing something obvious here, but I can't find the
> solution (including in the FAQ etc.).
>
> I have a vector of names of variables like this: NRes.x.y. where x and y
> are numbers. I want to extract these numbers as numbers to use
> elsewhere. I can extract the numbers as a list of characters using
> strsplit(), and convert that to a data frame, e.g.:
>
> NAMES=c("NRes.1.2.", "NRes.1.3.", "NRes.1.4.", "NRes.1.5.", "NRes.1.6.")
> NUMBERS=strsplit(gsub("NRes.","", NAMES, perl =T), '.', fixed = TRUE)
> NUMBERS.df=t(data.frame(NUMBERS))
>
> But I now want to convert the characters to be numeric. Using
> as.numeric(NUMBERS.df) converts them, but to a vector. How can I
> convert and keep as a data frame? I could use this:
>
> matrix(as.numeric(NUMBERS.df), ncol=dim(NUMBERS.df)[2])
>
> but I seem to be jumping through far too many hoops: there must be an
> easier way. An suggestions?
>
> Bob
>

How about this?

NUMBERS <- lapply(strsplit(NAMES, "\\."), "[", -1) as.data.frame(do.call("rbind", lapply(NUMBERS, as.numeric)))

--sundar



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