| predict.bSpline {splines} | R Documentation |
The predict methods for the classes that inherit from the
virtual classes bSpline and polySpline are used to
evaluate the spline or its derivatives. The plot method for a
spline object first evaluates predict with the x
argument missing, then plots the resulting xyVector with
type = "l".
## S3 method for class 'bSpline': predict(object, x, nseg=50, deriv=0, ...)
object |
An object that inherits from the bSpline or the
polySpline class. For plot.spline this argument is
called x. |
x |
A numeric vector of x values at which to evaluate the
spline. If this argument is missing a suitable set of x
values is generated as a sequence of nseq segments spanning
the range of the knots. For plot.spline the x
argument is as described under object above. |
nseg |
A positive integer giving the number of segments in a set
of equally-spaced x values spanning the range of the knots
in object. This value is only used if x is missing. |
deriv |
An integer between 0 and splineOrder(object) - 1
specifying the derivative to evaluate. |
... |
predict: further arguments passed to or from other methods.
plot: additional graphical parameters (see link{par}).
|
an xyVector with components
x |
the supplied or inferred numeric vector of x values |
y |
the value of the spline (or its deriv'th derivative)
at the x vector |
Douglas Bates and Bill Venables
xyVector,
interpSpline,
periodicSpline
ispl <- interpSpline( weight ~ height, women )
opar <- par(mfrow = c(2, 2), las = 1)
plot(predict(ispl, nseg = 201), # plots over the range of the knots
main = "Original data with interpolating spline", type = "l",
xlab = "height", ylab = "weight")
points(women$height, women$weight, col = 4)
plot(predict(ispl, nseg = 201, deriv = 1),
main = "First derivative of interpolating spline", type = "l",
xlab = "height", ylab = "weight")
plot(predict(ispl, nseg = 201, deriv = 2),
main = "Second derivative of interpolating spline", type = "l",
xlab = "height", ylab = "weight")
plot(predict(ispl, nseg = 401, deriv = 3),
main = "Third derivative of interpolating spline", type = "l",
xlab = "height", ylab = "weight")
par(opar)