BsBasis: B-spline basis

In mixAK: Multivariate Normal Mixture Models and Mixtures of Generalized Linear Mixed Models Including Model Based Clustering

B-spline basis

Description

It creates a B-spline basis based on a specific dataset. B-splines are assumed to have common boundary knots and equidistant inner knots.

Usage

BsBasis(degree, ninner, knotsBound, knots, intercept=FALSE,
        x, tgrid, Bname="B", plot=FALSE, lwd=1,
        col="blue", xlab="Time", ylab="B(t)",
        pch=16, cex.pch=1, knotcol="red")

Arguments

degree	degree of the B-spline.
ninner	number of inner knots.
knotsBound	2-component vector with boundary knots.
knots	knots of the B-spline (including boundary ones). If knots is given ninner and knotsBound are ignored.
intercept	logical, if FALSE, the first basis B-spline is removed from the B-spline basis and it is assumed that intercept is added to the statistical models used afterwards.
x	a numeric vector to be used to create the B-spline basis.
tgrid	if given then it is used to plot the basis.
Bname	label for the created columns with the B-spline basis.
plot	logical, if TRUE the B-spline basis is plotted.
lwd, col, xlab, ylab	arguments passed to the plotting function.
pch, cex.pch	plotting character and cex used to plot knots
knotcol	color for knots on the plot with the B-spline basis.

Value

A matrix with the B-spline basis. Number of rows is equal to the length of x.

Additionally, the resulting matrix has attributes:

degree	B-spline degree
intercept	logical indicating the presence of the intercept B-spline
knots	a numeric vector of knots
knotsInner	a numeric vector of innner knots
knotsBound	a numeric vector of boundary knots
df	the length of the B-spline basis (number of columns of the resulting object).
tgrid	a numeric vector which can be used on x-axis to plot the basis.
Xgrid	a matrix with length(tgrid) rows and df columns which can be used to plot the basis.

Author(s)

Arnošt Komárek [e-mail]

See Also

bs.

Examples

set.seed(20101126)
t <- runif(20, 0, 100)

oldPar <- par(mfrow=c(1, 2), bty="n")
Bs <- BsBasis(degree=3, ninner=3, knotsBound=c(0, 100), intercept=FALSE,
              x=t, tgrid=0:100, plot=TRUE)
print(Bs)

Bs2 <- BsBasis(degree=3, ninner=3, knotsBound=c(0, 100), intercept=TRUE,
               x=t, tgrid=0:100, plot=TRUE)
print(Bs2)
par(oldPar)

print(Bs)
print(Bs2)

mixAK documentation built on Sept. 25, 2023, 5:08 p.m.