interpSpline {splines} | R Documentation |
Create an interpolation spline, either from x
and y
vectors, or from a formula/data.frame combination.
interpSpline(obj1, obj2, bSpline = FALSE, period = NULL, na.action = na.fail)
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. |
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
.
Douglas Bates and Bill Venables
splineKnots
,
splineOrder
,
periodicSpline
.
ispl <- interpSpline( women$height, women$weight ) ispl2 <- interpSpline( weight ~ height, women ) # ispl and ispl2 should be the same plot( predict( ispl, seq( 55, 75, len = 51 ) ), type = "l" ) points( women$height, women$weight ) plot( ispl ) # plots over the range of the knots points( women$height, women$weight ) splineKnots( ispl )