| periodicSpline {splines} | R Documentation |
Create a periodic interpolation spline, either from x and
y vectors, or from a formula/data.frame combination.
periodicSpline(obj1, obj2, knots, period = 2*pi, ord = 4)
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. |
knots |
optional numeric vector of knot positions. |
period |
positive numeric value giving the period for the
periodic spline. Defaults to 2 * pi. |
ord |
integer giving the order of the spline, at least 2. Defaults
to 4. See splineOrder for a definition of the order of
a spline. |
An object that inherits from class spline. The object can be in
the B-spline representation, in which case it will be a
pbSpline object, or in the piecewise polynomial representation
(a ppolySpline object).
Douglas Bates and Bill Venables
xx <- seq( -pi, pi, len = 16 )[-1] yy <- sin( xx ) frm <- data.frame( xx, yy ) ( pispl <- periodicSpline( xx, yy, period = 2 * pi ) ) pispl2 <- periodicSpline( yy ~ xx, frm, period = 2 * pi ) stopifnot(all.equal(pispl, pispl2))# pispl and pispl2 are the same plot( pispl ) # displays over one period points( yy ~ xx, col = "brown") plot( predict( pispl, seq(-3*pi, 3*pi, len = 101) ), type = "l" )