dplyr replace na
df <- tibble(x = c(1, 2, NA), y = c("a", NA, "b"))
df %>% dplyr::mutate(x = replace_na(x, 0))
#> # A tibble: 3 x 2
#> x y
#> <dbl> <chr>
#> 1 1 a
#> 2 2 NA
#> 3 0 b
# To replace NA in two columns
df %>% replace_na(list(x = 0, y = "unknown"))
#> # A tibble: 3 x 2
#> x y
#> <dbl> <chr>
#> 1 1 a
#> 2 2 unknown
#> 3 0 b