R: Extract Knots from the Given Object

knots {splines2} | R Documentation

## Extract Knots from the Given Object

### Description

Methods for the generic function `knots` from the stats package to obtain internal or boundary knots from the objects produced by this package.

### Usage

    ## S3 method for class 'bSpline2'
    knots(Fn, type = c("internal", "boundary"), ...)

    ## S3 method for class 'dbs'
    knots(Fn, type = c("internal", "boundary"), ...)

    ## S3 method for class 'ibs'
    knots(Fn, type = c("internal", "boundary"), ...)

    ## S3 method for class 'mSpline'
    knots(Fn, type = c("internal", "boundary"), ...)

    ## S3 method for class 'iSpline'
    knots(Fn, type = c("internal", "boundary"), ...)

    ## S3 method for class 'cSpline'
    knots(Fn, type = c("internal", "boundary"), ...)

    ## S3 method for class 'bernsteinPoly'
    knots(Fn, type = c("internal", "boundary"), ...)

    ## S3 method for class 'naturalSpline'
    knots(Fn, type = c("internal", "boundary"), ...)

### Arguments

`Fn` | An `splines2` object produced by this package.
`type` | A character vector of length one indicating the type of knots to return. The available choices are `"internal"` for internal knots and `"Boundary"` for boundary knots.
`...` | Optional arguments that are not used now.

### Value

A numerical vector.

### Examples

    library(splines2)

    set.seed(123)
    x <- rnorm(100)

    ## B-spline basis
    bsMat <- bSpline(x, df = 8, degree = 3)

    ## extract internal knots placed based on the quantile of x
    (internal_knots <- knots(bsMat))

    ## extract boundary knots placed based on the range of x
    boundary_knots <- knots(bsMat, type = "boundary")
    all.equal(boundary_knots, range(x))

[Package splines2 version 0.4.2 Index]