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Last data update: 2014.03.03

R: Create an Interpolation Spline

interpSpline

R Documentation

Create an Interpolation Spline

Description

Create an interpolation spline, either from x and y vectors (default method), or from a formula / data.frame combination (formula method).

Usage

interpSpline(obj1, obj2, bSpline = FALSE, period = NULL,
             na.action = na.fail, sparse = FALSE)

Arguments

`obj1`	either a numeric vector of `x` values or a formula.
`obj2`	if `obj1` is numeric this should be a numeric vector of the same length. If `obj1` is a formula this can be an optional data frame in which to evaluate the names in the formula.
`bSpline`	if `TRUE` the b-spline representation is returned, otherwise the piecewise polynomial representation is returned. Defaults to `FALSE`.
`period`	an optional positive numeric value giving a period for a periodic interpolation spline.
`na.action`	a optional function which indicates what should happen when the data contain `NA`s. The default action (`na.omit`) is to omit any incomplete observations. The alternative action `na.fail` causes `interpSpline` to print an error message and terminate if there are any incomplete observations.
`sparse`	logical passed to the underlying `splineDesign`. If true, saves memory and is faster when there are more than a few hundred points.

Value

An object that inherits from (S3) class spline. The object can be in the B-spline representation, in which case it will be of class nbSpline for natural B-spline, or in the piecewise polynomial representation, in which case it will be of class npolySpline.

Author(s)

Douglas Bates and Bill Venables

Examples

require(graphics); require(stats)
ispl <- interpSpline( women$height, women$weight )
ispl2 <- interpSpline( weight ~ height,  women )
# ispl and ispl2 should be the same
plot( predict( ispl, seq( 55, 75, length.out = 51 ) ), type = "l" )
points( women$height, women$weight )
plot( ispl )    # plots over the range of the knots
points( women$height, women$weight )
splineKnots( ispl )

Results


R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(splines)
> png(filename="/home/ddbj/snapshot/RGM3/R_rel/result/splines/interpSpline.Rd_%03d_medium.png", width=480, height=480)
> ### Name: interpSpline
> ### Title: Create an Interpolation Spline
> ### Aliases: interpSpline
> ### Keywords: models
> 
> ### ** Examples
> 
> require(graphics); require(stats)
> ispl <- interpSpline( women$height, women$weight )
> ispl2 <- interpSpline( weight ~ height,  women )
> # ispl and ispl2 should be the same
> plot( predict( ispl, seq( 55, 75, length.out = 51 ) ), type = "l" )
> points( women$height, women$weight )
> plot( ispl )    # plots over the range of the knots
> points( women$height, women$weight )
> splineKnots( ispl )
 [1] 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>