Computing percentile rank in R [closed]

How can I add new variable into data frame which will be percentile rank of one of the variables? I can do this in Excel easily, but I really want to do that in R.

Thanks

Given a vector of raw data values, a simple function might look like

perc.rank <- function(x, xo)  length(x[x <= xo])/length(x)*100


where x0 is the value for which we want the percentile rank, given the vector x, as suggested on R-bloggers.

However, it might easily be vectorized as

perc.rank <- function(x) trunc(rank(x))/length(x)


which has the advantage of not having to pass each value. So, here is an example of use:

my.df <- data.frame(x=rnorm(200))
my.df <- within(my.df, xr <- perc.rank(x))

• 1. Your function does not mimic Excel's percentrank-function, which is good (+1) since the latter gives "strange" results (see my comparison). 2. I wouldn't name the data frame df, because df is an R function (the density of the F distribution, see ?df). Jun 15, 2011 at 11:04
• @Bernd Thanks. (1) There are some built-in functions for computing PR in various psychometrics packages. I think I grabbed this one from the CTT package a while ago. I didn't check against Excel because I don't have/use it. About (2) I seem to always forget about this! Let's go with my.* (Perl way) :-)
– chl
Jun 15, 2011 at 11:21
• @chl why is the trunc required? It seems rank will always return an integer anyway. May 10, 2018 at 18:38
• @Tyler Nope. In case there are ties, rank() defaults to taking the average of the tied values (cf. ties.method = c("average",...)).
– chl
May 11, 2018 at 13:15
• Beware that NA values should be removed! This can be done by adding x = x[!is.na(x)] Mar 21, 2021 at 16:55

If your original data.frame is called dfr and the variable of interest is called myvar, you can use dfr$myrank<-rank(dfr$myvar) for normal ranks, or dfr$myrank<-rank(dfr$myvar)/length(myvar) for percentile ranks.

Oh well. If you really want it the Excel way (may not be the simplest solution, but I had some fun using new (to me) functions and avoiding loops):

percentilerank<-function(x){
rx<-rle(sort(x))
smaller<-cumsum(c(0, rx$lengths))[seq(length(rx$lengths))]
larger<-rev(cumsum(c(0, rev(rx$lengths))))[-1] rxpr<-smaller/(smaller+larger) rxpr[match(x, rx$values)]
}


so now you can use dfr$myrank<-percentilerank(dfr$myvar)

HTH.

• 1 - (rank/size) gives you same as excel percentilerank Jun 15, 2011 at 11:24
• I got this from office.microsoft.com Jun 15, 2011 at 11:51
• An anonymous (attempted) editor tried to add the following comment: "Nice function but sometimes, unfortunately, the RLE may return vector of length < length(dfr\$myvar)". Aug 26, 2013 at 16:58
• Can you explain or link to the theory of this method? May 18, 2021 at 18:47

A problem with the presented answer is that it will not work properly, when you have NAs.

In this case, another possibility (inspired by the function from chl♦) is:

perc.rank <- function(x) trunc(rank(x,na.last = NA))/sum(!is.na(x))
quant <- function (x, p.ile) {
x[which.min(x = abs(perc.rank(x-(p.ile/100))))]
}


Here, x is the vector of values, and p.ile is the percentile by rank. 2.5 percentile by rank of (arbitrary) coef.mat may be calculated by:

quant(coef.mat[,3], 2.5)
[1] 0.00025


or as a single function:

quant <- function (x, p.ile) {
perc.rank <- trunc(rank(x,na.last = NA))/sum(!is.na(x))
x = na.omit(x)
x[which.min(x = abs(perc.rank(x-(p.ile/100))))]
}