A special smooth.construct method function for creating tensor product smooths from any
combination of single penalty marginal smooths.
# S3 method for tensor.smooth.spec
smooth.construct(object, data, knots)a smooth specification object of class tensor.smooth.spec,
usually generated by a term like te(x,z) in a gam model formula
a list containing just the data (including any by variable) required by this term,
with names corresponding to object$term (and object$by). The by variable
is the last element.
a list containing any knots supplied for basis setup --- in same order and with same names as data.
Can be NULL. See details for further information.
An object of class "tensor.smooth". See smooth.construct,
for the elements that this object will contain.
Tensor product smooths are smooths of several variables which allow the degree of smoothing to be different with respect
to different variables. They are useful as smooth interaction terms, as they are invariant to linear rescaling of the covariates,
which means, for example, that they are insensitive to the measurement units of the different covariates. They are also useful
whenever isotropic smoothing is inappropriate. See te, smooth.construct and
smooth.terms.
Wood, S.N. (2006) Low rank scale invariant tensor product smooths for generalized additive mixed models. Biometrics 62(4):1025-1036