CODEWITHSUNDEEP
rdplyr
Gooze
Gooze

Reputation: 110

Creating variable which is an interval concisely in R

I would like to create a new variable which is an interval, but as there are many intervals i want to know if i can write the code more concisely. I expect a for loop or a function might do the trick, but for now i have come up with:

require(dplyr)    
mtcars %>%
      mutate(
        mpg_interval = if_else(mpg < 15, "<15",
                               if_else(mpg < 20, "15-19",
                                       if_else(mpg < 25, "20-24", 
                                               ">24")))
      )

Is there an easier way to make many intervals (i.e. 100, which would be impractical to write out) using dplyr commands?

Upvotes: 2

Views: 1469

Answers (2)

user295691
user295691

Reputation: 7248

As @Aramis7d and @Florian point out in the comments above, cut is the tool for the job. If the number of intervals is too long to write out, then cut can be used with seq.

Consider

df <- data.frame(x=1:100)
df %>% mutate(rg=cut(x,c(seq(0, 25, 5), Inf))) %>%
  group_by(rg) %>% summarise(c = n())
# A tibble: 6 × 2
        rg     c
    <fctr> <int>
1    (0,5]     5
2   (5,10]     5
3  (10,15]     5
4  (15,20]     5
5  (20,25]     5
6 (25,Inf]    75

Upvotes: 2

F. Priv&#233;
F. Priv&#233;

Reputation: 11728

I think what you need is case_when():

mtcars %>%
  mutate(
    mpg_interval = case_when(
      mpg < 15 ~ "<15",
      mpg < 20 ~ "15-19",
      mpg < 25 ~ "20-24", 
      TRUE     ~ ">24"
    )
  )

Upvotes: 5

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