questionr (version 0.7.8)

rm.unused.levels: Remove unused levels

Description

This function removes unused levels of a factor or in a data.frame. See examples.

Usage

rm.unused.levels(x, v = NULL)

Arguments

x

a factor or a data frame

v

a list of variables (optional, if x is a data frame)

Author

Joseph Larmarange <[e-mail]>

Details

If x is a data frame, only factor variables of x will be impacted. If a list of variables is provided through v, only the unused levels of the specified variables will be removed.

Examples

df <- data.frame(v1 = c("a", "b", "a", "b"), v2 = c("x", "x", "y", "y"))
df$v1 <- factor(df$v1, c("a", "b", "c"))
df$v2 <- factor(df$v2, c("x", "y", "z"))
df
str(df)
str(rm.unused.levels(df))
str(rm.unused.levels(df, "v1"))