R中Ifelse语句的用法

Question

I have a data frame "var" and I need to get a vector output that satisfies the following conditions.

Basically, what I am trying to execute is the following: if the value of psqi_2_sleepstart1 is less than 15, comp21score needs to be assigned the value 0; between 16 and 30, comp21score needs to be assigned the value 1; between 31 and 60, comp21score needs to be assigned the value 2 and over 60 comp21score should take the value of 3. For example, if the data frame had values for psqi_2_sleepstart1 as 16, 40, 6 and 10; I want the output to be 1, 2, 0, 1. I was using the ifelse statement, but I got the error that argument "yes" is missing, with no default.

Here is my attempt:

for (i in 1: nrow(var)) {
ifelse (psqi_2_sleepstart1 <= 15) 
comp21score [i] <- 0
ifelse (psqi_2_sleepstart1 > 15 & psqi_2_sleepstart1 <= 30)
comp21score [i] <- 1
ifelse (psqi_2_sleepstart1 > 30 & psqi_2_sleepstart1 <= 60)
comp21score [i] <- 2
ifelse (psqi_2_sleepstart1 > 60)
comp21score [i] <- 3 
}
print (comp21score)

Does anyone have suggestions on what I might be able to use instead or how to avoid this error?

Thanks!

Answer 1

Just for kicks - here is a case_when dplyr example (as mentioned in the comments):

DF1 <- data.frame("score"= 0:20)

DF1 <- DF1 %>% mutate(value = case_when(
 score < 5 ~ 1,
 score >= 5| score < 10 ~ 2,
 score >= 10 ~ 3
 )
)

> DF1
    score value
1      0     1
2      1     1
3      2     1
.....

Answer 2

Use this layout instead:

x <- 2

if (x==0) {
  y <- log
} else if (x == 1) {
  y <- identity
} else if (x == 2) {
  y <- function(x) x^2
}