Compare two columns to get the names are repeated

[Kiviserr]

Hi, I'm new with R and in the forum, I know that probably it is easy to get the answer to my question but I didn't find how to look for it.
I will use an example to explain my doubts...
I have a document with two columns,
Column1:Matias, Pepe, Jorge, Elias, Paloma, Paula, estela
Column2:Paula, Javi, Ulises, Carlos, Pepe
What I want to do with R is to get the matches of both colums, the output I will want to get is "Paula, Pepe" which are the names that are in both columns, I only found the code to see if they are repeated in the same row using == but I would like to get even if one is in column1 row 3 and the other in column2 row 45.
Using match() with both columns I can get where the matches are but I would like to get which are the names that are repeated.
Thanks!

[phiggins]

Does this do what you intended?

library(tidyverse)
 
col1 <- as.character(expression(Matias, Pepe, Jorge, Elias, Paloma, Paula, Estela))
col2 <- as.character(expression(Paula, Javi, Ulises, Carlos, Pepe, Paco, Pedro))

dframe <- tibble(col1,col2)
dframe
#> # A tibble: 7 x 2
#>   col1   col2  
#>   <chr>  <chr> 
#> 1 Matias Paula 
#> 2 Pepe   Javi  
#> 3 Jorge  Ulises
#> 4 Elias  Carlos
#> 5 Paloma Pepe  
#> 6 Paula  Paco  
#> 7 Estela Pedro

dframe %>% 
  mutate(col1_dupe = !is.na(match(col1, col2))) ->
dframe2
dframe2
#> # A tibble: 7 x 3
#>   col1   col2   col1_dupe
#>   <chr>  <chr>  <lgl>    
#> 1 Matias Paula  FALSE    
#> 2 Pepe   Javi   TRUE     
#> 3 Jorge  Ulises FALSE    
#> 4 Elias  Carlos FALSE    
#> 5 Paloma Pepe   FALSE    
#> 6 Paula  Paco   TRUE     
#> 7 Estela Pedro  FALSE

dframe2$col1[dframe2$col1_dupe]
#> [1] "Pepe"  "Paula"

^{Created on 2020-12-21 by the reprex package (v0.3.0)}

[Kiviserr]

Yes! Thanks for your time.

[phiggins]

Took me a minute, but if you prefer a tidy/pipy approach, this works also:

library(tidyverse)
 
col1 <- as.character(expression(Matias, Pepe, Jorge, Elias, Paloma, Paula, Estela))
col2 <- as.character(expression(Paula, Javi, Ulises, Carlos, Pepe, Paco, Pedro))

dframe <- tibble(col1,col2)
dframe
#> # A tibble: 7 x 2
#>   col1   col2  
#>   <chr>  <chr> 
#> 1 Matias Paula 
#> 2 Pepe   Javi  
#> 3 Jorge  Ulises
#> 4 Elias  Carlos
#> 5 Paloma Pepe  
#> 6 Paula  Paco  
#> 7 Estela Pedro

dframe %>% 
  mutate(col1_dupe = !is.na(match(col1, col2))) %>% 
  mutate(result = if_else(condition = col1_dupe, 
                          true = col1, 
                          false = NA_character_))  %>% 
  na.omit() %>% 
  pull(result)
#> [1] "Pepe"  "Paula"

^{Created on 2020-12-21 by the reprex package (v0.3.0)}