Extract.factor

R Base 3.6.2

Extract or replace subsets of factors.

Syntax

# S3 method for factor
[(x, &#8230;, drop = FALSE)
# S3 method for factor
[[(x, &#8230;)
# S3 method for factor
[(x, &#8230;) &lt;- value
# S3 method for factor
[[(x, &#8230;) &lt;- value

Arguments

Parameter	Description
`x`	a factor
`…`	a specification of indices -- see Extract.
`drop`	logical. If true, unused levels are dropped.
`value`	character: a set of levels. Factor values are coerced to character.

Return Value

A factor with the same set of levels as x unless drop = TRUE.

Details

When unused levels are dropped the ordering of the remaining levels is preserved. If value is not in levels(x), a missing value is assigned with a warning. Any contrasts assigned to the factor are preserved unless drop = TRUE. The [[ method supports argument exact.

Examples

Example

# NOT RUN {
## following example(factor)
(ff <- factor(substring("statistics", 1:10, 1:10), levels = letters))
ff[, drop = TRUE]
factor(letters[7:10])[2:3, drop = TRUE]
# }