Replace column value by element of list from same column

June 16, 2023

I have the following dataframe. I applied the str_split() function to YEARS.

library(dplyr)
library(stringr)

YEARS <- c("2020/2021", "2021/2022", "2022/2023")  
VALUE <- c(10,5,3)  
x <- data.frame(YEARS, VALUE) %>%
     mutate(YEARS=str_split(YEARS, "/"))

I want to keep only the first element of the list for every YEARS, using dplyr if possible.
I tried this

x %>% mutate(YEARS=YEARS[[1]][1])

but it didn’t work and just changed every value to 2020 :

YEARS	VALUE
2020	10
2020	5
2020	3

I also tried with purrr but same result.
Does anyone kows why it’s not working properly and how to fix it ?

>Solution :

Try this:

library(dplyr)
library(stringr)
library(purrr)

YEARS <- c("2020/2021", "2021/2022", "2022/2023")
VALUE <- c(10, 5, 3)

x <- data.frame(YEARS, VALUE) %>%
  mutate(YEARS = map(YEARS, ~ str_split(.x, "/")[[1]][1]))