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 equallyspaced 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)