Use dplyr mutate when the values of a column are the names of a vector

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I have a dataframe with two columns, which are the initials of a name (col1) and an assigned value to it (col2)

dat  <- data.frame(col1 = c("A","B","C"), col2 = c(4,5,6)) %>% as_tibble()

And i have a named vector, whose names are the initials and the values are the full names

nam <- c("A" = "Andrew", "B" = "Bob", "C" = "Charles")

Given that i would like to have a third name with these names using dplyr's mutate once i am working in a pipe. The dataset should be something like this by the end.

dat2 <- data.frame(col1 = c("A","B","C"), col2 = c(4,5,6), col3 = c("Andrew","Bob","Charles")) %>% as_tibble()

How can i achieve this?

dplyr r
3 Answers

A possible solution:

library(dplyr)

dat %>% 
  mutate(col3 = nam[match(col1, names(nam))])

#> # A tibble: 3 × 3
#>   col1   col2 col3   
#>   <chr> <dbl> <chr>  
#> 1 A         4 Andrew 
#> 2 B         5 Bob    
#> 3 C         6 Charles
user_115644870

You could use recode() and pass a named character vector for unquote splicing with !!!.

dat %>%
  mutate(col3 = recode(col1, !!!nam))

# # A tibble: 3 × 3
#   col1   col2 col3   
#   <chr> <dbl> <chr>  
# 1 A         4 Andrew 
# 2 B         5 Bob    
# 3 C         6 Charles
user_100689850

You can use the following code:

library(tibble)
dat  <- data.frame(col1 = c("A","B","C"), col2 = c(4,5,6)) %>% as_tibble()
nam <- c("A" = "Andrew", "B" = "Bob", "C" = "Charles")

library(dplyr)
dat %>% 
  mutate(col3 = nam[as.character(col1)])
#> # A tibble: 3 × 3
#>   col1   col2 col3   
#>   <chr> <dbl> <chr>  
#> 1 A         4 Andrew 
#> 2 B         5 Bob    
#> 3 C         6 Charles

Created on 2022-07-13 by the reprex package (v2.0.1)

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