This is a translation of the SQL command NULLIF. It is useful
if you want to convert an annoying value to NA.
na_if(x, y)
| x | Vector to modify |
|---|---|
| y | Value to replace with NA |
A modified version of x that replaces any values that
are equal to y with NA.
coalesce() to replace missing values with a specified
value.
tidyr::replace_na() to replace NA with a value.
recode() to more generally replace values.
na_if(1:5, 5:1)#> [1] 1 2 NA 4 5#> [1] 100 -100 Inf 10100 / na_if(x, 0)#> [1] 100 -100 NA 10#> [1] "abc" "def" NA "ghi"# na_if() is particularly useful inside mutate(), # and is meant for use with vectors rather than entire data frames starwars %>% select(name, eye_color) %>% mutate(eye_color = na_if(eye_color, "unknown"))#> # A tibble: 87 x 2 #> name eye_color #> <chr> <chr> #> 1 Luke Skywalker blue #> 2 C-3PO yellow #> 3 R2-D2 red #> 4 Darth Vader yellow #> 5 Leia Organa brown #> 6 Owen Lars blue #> 7 Beru Whitesun lars blue #> 8 R5-D4 red #> 9 Biggs Darklighter brown #> 10 Obi-Wan Kenobi blue-gray #> # … with 77 more rows# na_if() can also be used with mutate() and across() # to mutate multiple columns starwars %>% mutate(across(where(is.character), ~na_if(., "unknown")))#> # A tibble: 87 x 14 #> name height mass hair_color skin_color eye_color birth_year sex gender #> <chr> <int> <dbl> <chr> <chr> <chr> <dbl> <chr> <chr> #> 1 Luke S… 172 77 blond fair blue 19 male mascu… #> 2 C-3PO 167 75 NA gold yellow 112 none mascu… #> 3 R2-D2 96 32 NA white, bl… red 33 none mascu… #> 4 Darth … 202 136 none white yellow 41.9 male mascu… #> 5 Leia O… 150 49 brown light brown 19 fema… femin… #> 6 Owen L… 178 120 brown, grey light blue 52 male mascu… #> 7 Beru W… 165 75 brown light blue 47 fema… femin… #> 8 R5-D4 97 32 NA white, red red NA none mascu… #> 9 Biggs … 183 84 black light brown 24 male mascu… #> 10 Obi-Wa… 182 77 auburn, wh… fair blue-gray 57 male mascu… #> # … with 77 more rows, and 5 more variables: homeworld <chr>, species <chr>, #> # films <list>, vehicles <list>, starships <list>