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rdataframefunctiondplyrfilter

Finding rows in a data.frame that are the same on one variable but different on another variable in R

In my DATA below, how could I filter the rows where the Nm values are the same but Descr values are different to achieve my Desired_out below?

DATA <- read.table(header=T, text ="
Cd    Nm     Descr
710   spa    Castilian
4260  spa    Spanish
2290  gr     Greek
1213  gr    Greek_b
1765  ger    German
2340  ita    Italian
")

Desired_output <- read.table(header=T, text ="
Cd    Nm     Descr
710   spa    Castilian
4260  spa    Spanish
2290  gr     Greek
1213  gr    Greek_b")
Solution

  • With dplyr, detecting duplicated entries with vec_duplicate_detect from vctrs

    library(dplyr)

DATA %>% 
  filter(all(!vctrs::vec_duplicate_detect(Descr)) & n() > 1, .by = Nm)
    Cd  Nm     Descr
1  710 spa Castilian
2 4260 spa   Spanish
3 2290  gr     Greek
4 1213  gr   Greek_b