[R] create new variable: percentile value of variable in data frame

Jonathan Beard jonathan.j.beard at gmail.com
Fri May 28 21:00:46 CEST 2010

Hello all,

Thanks in advance for you attention.
I would like to generate a third value that represents the quantile
value of a variable in a data frame.

# generating data

x <- as.matrix(seq(1:30))
y <- as.matrix(rnorm(30, 20, 7))
tmp1 <- cbind(x,y)
dat <- as.data.frame(tmp1)
colnames(dat) <- c("id", "score")

#  finding percentiles of "score"

qs <- as.matrix(quantile(dat$score, type=3, probs = seq(0,1,.1)))
colnames(qs) <- c( "score")

#  is there a way to put the quantile value for a value of 'score'
into a new variable,
#  such that the new data frame would have three variables: id, score
and q.score?

##  running R version 2.8.1 (2008-12-22) on Vista

Thanks so much!


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