Build crossbasis

Creates cross-basis using natural splines for regression in DLIM

Usage

cross_basis(
  x,
  M,
  L = NULL,
  argmod = list(),
  arglag = list(),
  model_type = "standard"
)

Arguments

x

a numeric time series vector of length n or matrix of lagged exposures (columns) for n individuals (rows)

M

vector of length n containing modifier values

L

a numeric vector of length 1 containing the number of lag terms. This is required if x is vector, and is not used if x is a matrix.

argmod

a list: $fun is the spline function for the modifier ("ps" or "cr" to penalize), $arg is a list of arguments for the spline function (must be named by argument), $df is the degrees of freedom, $sp is optional smoothing parameter

arglag

a list: $fun is the spline function for the lag ("ps" or "cr" to penalize), $arg is a list of arguments for the spline function (must be named by argument), $df is the degrees of freedom, $sp is optional smoothing parameter

model_type

"linear" for a DLIM with linear interaction, "quadratic" for a DLIM with quadratic interaction, "standard" for a DLIM with splines

Value

This function returns a list of 5 or 6 elements:

cb

cross-basis (matrix)

B_lag

lag basis (basis matrix)

B_mod

modifier basis (basis matrix)

df_l

lag degrees of freedom (numeric)

df_m

modifier degrees of freedom (numeric)

L

number of lags (numeric)

Slist

lag and modifier penalty matrices, if penalizing (list)

See also

dlim

Type vignette('dlimOverview') for a detailed description.