How can I exclude pieces of data in R?

Question

I am new to R studio and having a little trouble. I am trying to output unique counties form a data set. So far I have

sort(unique(x$Location) )

[1] Africa Asia Carlow Cavan Cork Dublin Europe Galway

[9] Kildare Laois Louth Mayo Meath

13 Levels: Africa Asia Carlow Cavan Cork Dublin Europe ... Meath

I want that list but without "Africa", "Asia" and "Europe" What function should I use to remove them?

Answer 1

由于您有因子变量，您可以使用levels来获得唯一级别，然后使用setdiff删除c('Africa', 'Asia', 'Europe') 。

lvls <- setdiff(levels(x$Location), c('Africa', 'Asia', 'Europe'))

Answer 2

i would do this:

library(dplyr)

x <- x %>%
filter(Location != "Africa", Location != "Asia", Location != "Europe")

sort(unique(x$Location))

Answer 3

library(dplyr)

(x %>%
  filter(!Location %in% c("Africa", "Asia", "Europe")) %>%
  pull(Location) %>%
  unique() ->
  locations)