CODEWITHSUNDEEP
rdplyr
Nader Mehri
Nader Mehri

Reputation: 556

sorting the levels of a factor variable using a if statment

Using the below toy data, how can I sort x if y=a, y=b etc. I prefer to use the sample code to do so but I could not involve an if statement. I belive a loop would be really efficient.

#my data

dataframe <- data.frame(
  x = c("apple", "orange", "banana", "strawberry"),
  y = c("a", "b", "a", "b"),
)

# my prefered code without if statement

data.frame$x <- factor(
  data.frame$x,
  levels = c(
    "apple", "orange", "banana", "strawberry"),
  labels = c(
    "apple", "banana", "orange", "strawberry")
)

Upvotes: 0

Views: 41

Answers (1)

akrun
akrun

Reputation: 887118

We can arrange on a logical vector and then change the levels

library(dplyr)
dataframe1 <- dataframe %>% 
     arrange(y == 'b', x) %>%
     mutate(x = factor(x, levels = unique(x)))

dataframe1$x
#[1] apple      banana     orange     strawberry
#Levels: apple banana orange strawberry

If there are more than 2 unique elements in 'y', then the option is to use factor on the 'y' with levels specified in that order

dataframe1 <- dataframe %>%
    arrange(factor(y, levels = c('a', 'b')), x) %>%
    mutate(x = factor(x, levels = unique(x)))

data

dataframe <- structure(list(x = c("apple", "orange", "banana", "strawberry"
), y = c("a", "b", "a", "b")), class = "data.frame", row.names = c(NA, 
-4L))

Upvotes: 1

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