How to format a number as percentage in R?
One of the things that used to perplex me as a newby to R was how to format a number as a percentage for printing.
For example, display 0.12345 as 12.345%. I have a number of workarounds for this, but none of these seem to be "newby friendly". For example:
set.seed(1)
m <- runif(5)
paste(round(100*m, 2), "%", sep="")
[1] "26.55%" "37.21%" "57.29%" "90.82%" "20.17%"
sprintf("%1.2f%%", 100*m)
[1] "26.55%" "37.21%" "57.29%" "90.82%" "20.17%"
Question: Is there a base R function to do this? Alternatively, is there a widely used package that provides a convenient wrapper?
Despite searching for something like this in ?format, ?formatC and ?prettyNum, I have yet to find a suitably convenient wrapper in base R. ??"percent" didn't yield anything useful. library(sos); findFn("format percent") returns 1250 hits - so again not useful. ggplot2 has a function percent but this gives no control over rounding accuracy.
Answer
Even later:
As pointed out by @DzimitryM, percent() has been "retired" in favor of label_percent(), which is a synonym for the old percent_format() function.
label_percent() returns a function, so to use it, you need an extra pair of parentheses.
library(scales)
x <- c(-1, 0, 0.1, 0.555555, 1, 100)
label_percent()(x)
## [1] "-100%" "0%" "10%" "56%" "100%" "10 000%"
Customize this by adding arguments inside the first set of parentheses.
label_percent(big.mark = ",", suffix = " percent")(x)
## [1] "-100 percent" "0 percent" "10 percent"
## [4] "56 percent" "100 percent" "10,000 percent"
An update, several years later:
These days there is a percent function in the scales package, as documented in krlmlr's answer. Use that instead of my hand-rolled solution.
Try something like
percent <- function(x, digits = 2, format = "f", ...) {
paste0(formatC(100 * x, format = format, digits = digits, ...), "%")
}
With usage, e.g.,
x <- c(-1, 0, 0.1, 0.555555, 1, 100)
percent(x)
(If you prefer, change the format from "f" to "g".)