dlnm (version 2.3.9)

lin: Generate a Basis Matrix with a Variable as Linear

Description

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.

Usage

lin(x, intercept=FALSE)

Arguments

x

the predictor variable. Missing values are allowed.

intercept

logical. If TRUE, an intercept is included in the basis matrix, namely a vector of 1's.

Value

A matrix object of class "lin". It contains the attribute intercept.

Details

The function returns a basis matrix with the un-transformed variable, optionally with an intercept if intercept=TRUE.

See Also

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.

Examples

# NOT RUN {
### 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")
# }