CODEWITHSUNDEEP
rquantile
user3344266
user3344266

Reputation: 69

R: How to create a Quartile Column within Groups

I have managed to create the column "qaurtile" with the following code, but I'd also like to create a column called "quartile_team" that shows the quartiles within each team. I can't figure out how to do this.

Help is appreciated,

Paul

# generate dataset
teams <- c(rep("East", 6), rep("West", 8), rep("North", 7), rep("South", 9))
time_spent <- rnorm(30)
dataset <- as.data.frame(cbind(teams, time_spent))
dataset$time_spent <- as.numeric(dataset$time_spent)

# create quartile column
 dataset <- within(dataset,
                    quartile <- cut(x = time_spent,
                                    breaks = quantile(time_spent, probs = seq(0, 1, 0.25)),
                                    labels = FALSE,
                                    include.lowest = TRUE))

Upvotes: 0

Views: 1703

Answers (1)

alexizydorczyk
alexizydorczyk

Reputation: 920

There's far better way to do this but a quick and dirty solution would probably use plyr. I'll use your function for calculating quartiles within:

library(plyr)


ddply(dataset, "teams", function(team){

  team_quartile <- cut(x = team$time_spent, breaks = quantile(team$time_spent, probs = seq(0, 1, 0.25)),
                       labels = FALSE,
                       include.lowest = TRUE)

  data.frame(team, team_quartile)
})

Basically, you want to split the data frame up by the team and then perform the calculation on each subset of the data frame. You could use tapply for this as well.

Upvotes: 2

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