[R] Remove non-numerical columns from data frame

From: Markus Mühlbacher <muehliman_at_yahoo.com>
Date: Sat, 26 Jul 2008 07:19:54 -0700 (PDT)


My question sounds simple, but as I am desperatly searchin for a solution I am asking you all. :)

I try to filter out all non-numeric columns of a data frame using a for loop to go through all columns. My if clause looks like this:

        for(j in 1:length(data)) {

                if(!is.numeric(data[j])) skip <- "not numeric")

When I do: is.numeric(data$vol) i get TRUE as result: unfortunately this is not applicable in a for loop, because i need to go through all of the columns using j.
I also tried to paste data$ and the name of the column , but this is always a character.
When I do: is.numeric(data[257]) i get FALSE as result   (257 is the corresponding column index to "vol")

Help needed! Thanks!

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