Marc Schwartz wrote:
On Mon, 2004-07-12 at 01:16, Andrew Criswell wrote:
Hello All:
Suppose the following little data frame:
> x <- data.frame(dog = c(3,4,6,2,8), cat = c(8,2,3,6,1)) > > x$cat [1] 8 2 3 6 1 >
How can I get the paste() function to do the same thing. The command below is obviously wrong
> paste(x, cat, sep = "$")
You need to quote the "x" and the "cat" as explicit names, otherwise the objects 'x' and 'cat' are passed as arguments. 'x' in this case being your data frame and 'cat' being the function cat().
Try this:
eval(parse(text = paste("x", "cat", sep = "$")))
[1] 8 2 3 6 1
OK. That thread gets boring, because nobody is sure what the questioner is asking. Anyway, I guess Andrew Criswell is looking for:
get("x")[["cat"]]- Use [[]] rather than $ for subsetting with characters ($ is just provided for convenience and not that helpful here).
- Use get() to get values from objects specified in form of a character vector.
Uwe Ligges
HTH,
Marc Schwartz
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