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Construct design matrices
Syntax
model.matrix(formula=, data=)
Arguments
formula
|
A model formula or terms object
|
data
|
A data frame created with model.frame
|
Description
Creates a design matrix from the description given in
terms(formula)
, using the data in data
. data
must
contain columns with the same names as would be created by a call to
model.frame(formula)
or, more precisely, by evaluating
attr(terms(formula),"variables")
. There may be other columns and
the order is not important.
Value
The design matrix for a regression model with the specified formula and
data.
References
Chambers and Hastie: "Statistical Models in S"
See Also
model.frame
, LANK(model.data.frame), LANK(terms)
Examples
data(trees)
ff<-log(Volume)~log(Height)+log(Girth)
m<-model.frame(ff,trees)
mat<-model.matrix(ff,m)