Description Usage Arguments Details Value Note Author(s) See Also Examples
Function to interpolate the Z-matrix for LME smoothing spline fits
from one set of values of the time
covariate to another.
1 | approx.Z(Z, oldtimes, newtimes)
|
Z |
Z-matrix with rows corresponding to the sorted unique
values of the |
oldtimes |
original (sorted) values for |
newtimes |
new (sorted) values for |
Uses linear interpolation of each column of the Z-matrix, regarded as
a function of time, with the times given by oldtimes
.
A matrix corresponding to an interpolated spline matrix. Can be used
with smspline()
for fitting LME splines with random effects
corresponding to a different set of values of the time
covariate
than those represented in the data, or as part of the ‘newdata’ argument
prediction from an existing model, to obtain predictions at points
not represented in the data using predict.lme()
.
Linear interpolation works well here because the spline basis functions are approximately piecewise linear.
Rod Ball rod.ball@scionresearch.com www.scionresearch.com
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