Basis for a piecewise linear spline with meaningful coefficients

This function is based on the native R function lspline from the lspline package. This function computes the basis of piecewise-linear spline such that, depending on the argument marginal, the coefficients can be interpreted as (1) slopes of consecutive spline segments, or (2) slope change at consecutive knots.

lsplineDS(x = x, knots = NULL, marginal = FALSE, names = NULL)

Arguments

x

the name of the input numeric variable

knots

numeric vector of knot positions

marginal

logical, how to parametrize the spline, see Details

names,

character, vector of names for constructed variables

Value

an object of class "lspline" and "matrix", which its name is specified by the newobj argument (or its default name "lspline.newobj"), is assigned on the serverside.

Details

If marginal is FALSE (default) the coefficients of the spline correspond to slopes of the consecutive segments. If it is TRUE the first coefficient correspond to the slope of the first segment. The consecutive coefficients correspond to the change in slope as compared to the previous segment.

Author

Demetris Avraam for DataSHIELD Development Team