splines2 0.5.0

New features

• Added a new function named nsk() for natural cubic spline basis functions following the function survival::nsk() (of survival package version 3.2-8).
• Added plot() methods to quickly visualize the spline basis functions.
• Added $ method to extract an attribute of the returned splines2 object.
• Added a new argument named periodic to bSpline() for periodic B-splines and a new class named PeriodicBSpline to the Rcpp interface: issue 19.
• Added a new argument named coef to the predict() methods to compute the responding spline function and made it possible to obtain the derivatives or update spline basis functions by passing ... to the update() methods.
• Added a new argument named trim to naturalSpline() to set the default boundary knots after trimming a fraction of observations.
• Added a new argument named warn.outside and a package option named splines2.warn.outside to specify if a warning should be thrown out for B-splines, etc. when any x is placed outside the boundary.
• Added the following function aliases to encourage the use in a model formula:
  • bsp() = bSpline()
  • msp() = mSpline()
  • isp() = iSpline()
  • csp() = cSpline()
  • nsp() = naturalSpline()
  • bpoly() = bernsteinPoly()
• Added a matrix named H to the attribution of objects for natural cubic splines so that users may transform cubic B-splines (from other software/packages) to the natural cubic splines (returned by naturalSpline()/nsp() or nsk()).

Major changes

• Adjusted the class order of the returned objects.
• Adjusted the default placement of the internal knots from the specified df to be equidistant if the internal knots resulted from quantiles are problematic. A warning will be thrown out in that case.