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

Arguments

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.