Extract.factor {base} | R Documentation |

## Extract or Replace Parts of a Factor

### Description

Extract or replace subsets of factors.

### Usage

```
## S3 method for class 'factor'
x[..., drop = FALSE]
## S3 method for class 'factor'
x[[...]]
## S3 replacement method for class 'factor'
x[...] <- value
## S3 replacement method for class 'factor'
x[[...]] <- value
```

### Arguments

`x` |
a factor. |

`...` |
a specification of indices – see |

`drop` |
logical. If true, unused levels are dropped. |

`value` |
character: a set of levels. Factor values are coerced to character. |

### 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`

.

### Value

A factor with the same set of levels as `x`

unless `drop = TRUE`

.

### See Also

### Examples

```
## following example(factor)
(ff <- factor(substring("statistics", 1:10, 1:10), levels = letters))
ff[, drop = TRUE]
factor(letters[7:10])[2:3, drop = TRUE]
```

[Package

*base*version 4.4.0 Index]