initial_params {registr}

Create initial parameters for (inverse) warping functions

Description

Dependent on the specific type of warping functions, this function creates a vector of initial parameters. For "nonparametric" warpings that are based on a given spline basis matrix, the initial parameters are defined s.t. the resulting (inverse) warping function equals a diagonal line. For "piecewise_linear2" warpings a fixed parameter vector is returned.

Usage

initial_params(warping = "nonparametric", K, t_vec)

Arguments

warping

If nonparametric (default), inverse warping functions are estimated nonparametrically. If piecewise_linear2 they follow a piecewise linear function with 2 knots.

K

Spline basis matrix defined over the interval c(t_min, t_max).

t_vec

Vector of the observed and potentially irregular time grid.