# interpSpline

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##### Create an Interpolation Spline

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

Keywords
models
##### Usage
interpSpline(obj1, obj2, bSpline = FALSE, period = NULL, na.action = na.fail)
##### 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 NAs. 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.
##### Value

An object that inherits from 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.

splineKnots, splineOrder, periodicSpline.
library(splines) 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 )