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rr-factor

R how to change one of the level to NA

I have a data set and one of its column has factor levels "a" "b" "c" "NotPerformed". How can I change all the "NotPerformed" factors to NA?

Solution

  • Set the level to NA:

    x <- factor(c("a", "b", "c", "NotPerformed"))
x
## [1] a            b            c            NotPerformed
## Levels: a b c NotPerformed
levels(x)[levels(x)=='NotPerformed'] <- NA
x
## [1] a    b    c    <NA>
## Levels: a b c

    Note that the factor level is removed.