na_if {dplyr}

Convert values to NA

Description

This is a translation of the SQL command NULLIF. It is useful if you want to convert an annoying value to NA.

Usage

na_if(x, y)

Arguments

x

Vector to modify

y

Value or vector to compare against. When x and y are equal, the value in x will be replaced with NA.

y is cast to the type of x before comparison.

y is recycled to the size of x before comparison. This means that y can be a vector with the same size as x, but most of the time this will be a single value.

Value

A modified version of x that replaces any values that are equal to y with NA.

See Also

coalesce() to replace missing values with a specified value.

tidyr::replace_na() to replace NA with a value.

Examples

na_if(1:5, 5:1)

x <- c(1, -1, 0, 10)
100 / x
100 / na_if(x, 0)

y <- c("abc", "def", "", "ghi")
na_if(y, "")

# `na_if()` allows you to replace `NaN` with `NA`,
# even though `NaN == NaN` returns `NA`
z <- c(1, NaN, NA, 2, NaN)
na_if(z, NaN)

# `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"))

# `na_if()` can also be used with `mutate()` and `across()`
# to alter multiple columns
starwars %>%
   mutate(across(where(is.character), ~na_if(., "unknown")))