rduplicatesrowmultiple-columnsdrop-duplicates

Remove 'duplicate' rows based on combinations in two columns


I have this example data.frame:

df1 <- data.frame(v1 = c('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H'),
                  v2 = c('B', 'A', 'D', 'C', 'F', 'E', 'H', 'G'),
                  value = c(1.12, 1.12, 12.52, 12.52, 3.19, 3.19, 12.52, 12.52))
> df1
  v1 v2 value
1  A  B  1.12
2  B  A  1.12
3  C  D 12.52
4  D  C 12.52
5  E  F  3.19
6  F  E  3.19
7  G  H 12.52
8  H  G 12.52

Combinations such as A and B in row 1 are the same to me as combinations such as B and A, where values in column value are also the same. How can I remove rows which for my purpose are duplicates?

Expected result:

df2 <- data.frame(v1 = c('A', 'C', 'E', 'G'),
                  v2 = c('B', 'D', 'F', 'H'),
                  value = c(1.12, 12.52, 3.19, 12.52))

> df2
  v1 v2 value
1  A  B  1.12
2  C  D 12.52
3  E  F  3.19
4  G  H 12.52

Solution

  • The idea is to consider v1 and v2 interchangeable.

    df1 <- data.frame(v1 = c('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H'),
                      v2 = c('B', 'A', 'D', 'C', 'F', 'E', 'H', 'G'),
                      value = c(1.12, 1.12, 12.52, 12.52, 3.19, 3.19, 12.52, 12.52))
    
    ### with tidyverse:
    
    library(dplyr)
    #> 
    #> Attaching package: 'dplyr'
    #> The following objects are masked from 'package:stats':
    #> 
    #>     filter, lag
    #> The following objects are masked from 'package:base':
    #> 
    #>     intersect, setdiff, setequal, union
    library(purrr)
    
    df2 <- df1 %>%
            mutate(combination = pmap_chr(list(v1, v2), ~ paste(sort(c(..1, ..2)), collapse = ","))) %>%
            filter(!duplicated(combination)) %>%
            select(-combination)
    
    df2
    #>   v1 v2 value
    #> 1  A  B  1.12
    #> 2  C  D 12.52
    #> 3  E  F  3.19
    #> 4  G  H 12.52
    
    ### Base R:
    df2 <- df1[!duplicated(t(apply(df1[, c("v1", "v2")], 1, sort))), ]
    
    df2
    #>   v1 v2 value
    #> 1  A  B  1.12
    #> 3  C  D 12.52
    #> 5  E  F  3.19
    #> 7  G  H 12.52
    

    Created on 2023-12-24 with reprex v2.0.2