rm.unused.levels | R Documentation |
This function removes unused levels of a factor or in a data.frame. See examples.
rm.unused.levels(x, v = NULL)
x |
a factor or a data frame |
v |
a list of variables (optional, if |
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.
Joseph Larmarange <joseph@larmarange.net>
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"))
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