Missing values (5)

But %in% works differently:

• NA %in% NA returns TRUE: here NA is just regarded as a special value

flights |>
  filter(dep_time %in% c(NA, 0800))

## # A tibble: 8,803 × 19
##     year month   day dep_time sched_dep_time dep_delay arr_time sched_arr_time
##    <int> <int> <int>    <int>          <int>     <dbl>    <int>          <int>
##  1  2013     1     1      800            800         0     1022           1014
##  2  2013     1     1      800            810       -10      949            955
##  3  2013     1     1       NA           1630        NA       NA           1815
##  4  2013     1     1       NA           1935        NA       NA           2240
##  5  2013     1     1       NA           1500        NA       NA           1825
##  6  2013     1     1       NA            600        NA       NA            901
##  7  2013     1     2      800            810       -10     1102           1116
##  8  2013     1     2       NA           1540        NA       NA           1747
##  9  2013     1     2       NA           1620        NA       NA           1746
## 10  2013     1     2       NA           1355        NA       NA           1459
## # ℹ 8,793 more rows
## # ℹ 11 more variables: arr_delay <dbl>, carrier <chr>, flight <int>,
## #   tailnum <chr>, origin <chr>, dest <chr>, air_time <dbl>, distance <dbl>,
## #   hour <dbl>, minute <dbl>, time_hour <dttm>