R 中具有多个输出的管道和 If 语句

Question

What am I missing here...

df <- data.frame("sn" = 1:3, "age" = c(21,15, 18), "name" = c("John","Dora", "Lynn"))

df %>% if (df$age >= 18){
  df$drive <- "yes"
  df$vote <- "yes"
}

Error in if (.) df$age >= 18 else { : 
  argument is not interpretable as logical

...in trying to make this dataframe?

  sn age name drive vote
1  1  21 John   yes  yes
2  2  15 Dora    no   no
3  3  21 Lynn   yes  yes

Answer 1

We could use ifelse or case_when as these are vectorized while if/else is not ie it expects a vector of length 1 as logical vector

library(dplyr)
df %>%
     mutate(drive = case_when(age >=18 ~ "yes", TRUE ~"no"),
             vote = drive)

In base R , we can do

df[c('drive', 'vote')] <- 'no'
df[df$agge >=18, c('drive', 'vote')] <- 'yes'

Answer 2

We can compare age with 18 and assign "yes" , "no" values based on that. Since the age for driving and voting is the same we can use the same values for vote as well.

df$drive <- c('no', 'yes')[(df$age >= 18) + 1]
df$vote <- df$drive
df

#  sn age name drive vote
#1  1  21 John   yes  yes
#2  2  15 Dora    no   no
#3  3  18 Lynn   yes  yes

We can also use ifelse / if_else to get output here but it would be slower than the above approach.