Take a data.frame x and convert all columns of class character that appear to be numeric into numeric

charnum2num.r

charnum2num <- function(x) {
    # Purpose
    # Take a data.frame x and convert all columns of class character that appear to be numeric into numeric
    # x is a data.frame
    # code taken from library(Hmisc) and included here to avoid the dependency
    all.is.numeric <- function (x, what = c("test", "vector"), extras = c(".", "NA")) 
    {
        what <- match.arg(what)
        old <- options(warn = -1)
        on.exit(options(old))
        x <- sub("[[:space:]]+$", "", x)
        x <- sub("^[[:space:]]+", "", x)
        xs <- x[x %nin% c("", extras)]
        isnum <- !any(is.na(as.numeric(xs)))
        if (what == "test") 
            isnum
        else if (isnum) 
            as.numeric(x)
        else x
    }
    
    varsnumeric <- sapply(x, function(X) all.is.numeric(X, extras=c(NA, ".", "NA")))
    for (i in seq(varsnumeric)) {
        if (varsnumeric[i]) {
            x[,i] <- as.numeric(x[,i])
        }
    }
    x
}