R: vctr (vector) S3 class

new_vctr {vctrs} | R Documentation

## vctr (vector) S3 class

### Description

This abstract class provides a set of useful default methods that makes it considerably easier to get started with a new S3 vector class. See `vignette("s3-vector")` to learn how to use it to create your own S3 vector classes.

### Usage

    new_vctr(.data, ..., class = character(), inherit_base_type = NULL)

### Arguments

`.data` | Foundation of class. Must be a vector
`...` | Name-value pairs defining attributes
`class` | Name of subclass.
`inherit_base_type` | A single logical, or `NULL`. Does this class extend the base type of `.data`? i.e. does the resulting object extend the behaviour of the underlying type? Defaults to `FALSE` for all types except lists, which are required to inherit from the base type.

### Details

List vctrs are special cases. When created through `new_vctr()`, the resulting list vctr should always be recognized as a list by `vec_is_list()`. Because of this, if `inherit_base_type` is `FALSE` an error is thrown.

### Base methods

The vctr class provides methods for many base generics using a smaller set of generics defined by this package. Generally, you should think carefully before overriding any of the methods that vctrs implements for you as they've been carefully planned to be internally consistent.

- `[[` and `[` use `NextMethod()` dispatch to the underlying base function, then restore attributes with `vec_restore()`. `rep()` and `length<-` work similarly.

- `[[<-` and `[<-` cast `value` to same type as `x`, then call `NextMethod()`.

- `as.logical()`, `as.integer()`, `as.numeric()`, `as.character()`, `as.Date()` and `as.POSIXct()` methods call `vec_cast()`. The `as.list()` method calls `[[` repeatedly, and the `as.data.frame()` method uses a standard technique to wrap a vector in a data frame.

- `as.factor()`, `as.ordered()` and `as.difftime()` are not generic functions in base R, but have been reimplemented as generics in the `generics` package. `vctrs` extends these and calls `vec_cast()`. To inherit this behaviour in a package, import and re-export the generic of interest from `generics`.

- `==`, `!=`, `unique()`, `anyDuplicated()`, and `is.na()` use `vec_proxy()`.

- `<`, `<=`, `>=`, `>`, `min()`, `max()`, `range()`, `median()`, `quantile()`, and `xtfrm()` methods use `vec_proxy_compare()`.

- `+`, `-`, `/`, `*`, `^`, `%%`, `%/%`, `!`, `&`, and `|` operators use `vec_arith()`.

- Mathematical operations including the Summary group generics (`prod()`, `sum()`, `any()`, `all()`), the Math group generics (`abs()`, `sign()`, etc), `mean()`, `is.nan()`, `is.finite()`, and `is.infinite()` use `vec_math()`.

- `dims()`, `dims<-`, `dimnames()`, `dimnames<-`, `levels()`, and `levels<-` methods throw errors.

[Package vctrs version 0.3.2 Index]