Generate a Basis Matrix with a Variable as Linear
The function generates a basis matrix including a linear un-transformed variable. It is meant to be used internally by onebasis
and crossbasis
and not directly run by the users.
lin(x, intercept=FALSE)
x |
the predictor variable. Missing values are allowed. |
intercept |
logical. If |
The function returns a basis matrix with the un-transformed variable, optionally with an intercept if intercept=TRUE
.
A matrix object of class "lin"
. It contains the attribute intercept
.
This function is mainly used internally thorugh onebasis
to create basis matrices. It is not exported in the namespace, and can be accessed through the triple colon operator ':::
' (see Examples below).
Antonio Gasparrini <antonio.gasparrini@lshtm.ac.uk>
onebasis
to generate basis matrices and crossbasis
to generate cross-basis matrices.
See dlnm-package
for an introduction to the package and for links to package vignettes providing more detailed information.
### simple use (accessing non-exported function through ':::') dlnm:::lin(1:5) dlnm:::lin(1:5, intercept=TRUE) ### use as an internal function in onebasis (note the centering) b <- onebasis(chicagoNMMAPS$pm10, "lin") summary(b) model <- glm(death ~ b, family=quasipoisson(), chicagoNMMAPS) pred <- crosspred(b, model, at=0:60) plot(pred, xlab="PM10", ylab="RR", main="RR for PM10")
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