ggplot2 aes_string() fails to handle names starting with numbers or containing spaces

Question

If the column names of a data.frame are started with numbers, or have spaces, aes_string() fails to handle them:

foo=data.frame(\"1         


        

Answer 1

The original question asked how to modify a value of a variable so it is acceptable to ggplot() when the value is not know beforehand.

Write a function that adds back-ticks to the beginning and end of the value of the variable:

# ggName -> changes a string so it is enclosed in back-ticks.
#   This can be used to make column names that have spaces (blanks)
#   or non-letter characters acceptable to ggplot2.
#   This version of the function is vectorized with sapply.
ggname <- function(x) {
    if (class(x) != "character") {
        return(x)
    }
    y <- sapply(x, function(s) {
        if (!grepl("^`", s)) {
            s <- paste("`", s, sep="", collapse="")
        }
        if (!grepl("`$", s)) {
            s <- paste(s, "`", sep="", collapse="")
        }
    }
    )
    y 
}

Examples:

ggname(12)

[1] 12

ggname("awk ward")

"`awk ward`"

l <- c("awk ward", "no way!")
ggname(l)

"`awk ward`" "`no way!`"