Description Usage Arguments Details Value Author(s) See Also Examples
View source: R/dropEmptyLevels.R
Reform a factor so that only necessary levels are kept.
1 |
x |
a factor or a vector to be converted to a factor. |
In general, the levels of a factor, levels(x)
, may include values that never actually occur.
This function drops any levels of that do not occur.
If x
is not a factor, then the function returns factor(x)
.
If x
is a factor, then the function returns the same value as factor(x)
or x[,drop=TRUE]
but somewhat more efficiently.
A factor with the same values as x
but with a possibly reduced set of levels.
Gordon Smyth
1 2 3 | x <- factor(c("a","b"), levels=c("c","b","a"))
x
dropEmptyLevels(x)
|
Loading required package: limma
[1] a b
Levels: c b a
[1] a b
Levels: b a
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.