Get and Set Contrast Matrices
Usage
contrasts(x)
contrasts(x) <- ctr
Arguments
x
|
a factor.
|
ctr
|
either a matrix whose columns give coefficients
for contrasts in the levels of x, or the (quoted)
name of a function which computes such matrices.
|
Value
These functions are used to set and view the
contrasts associated with a factor.
If contrasts are not set for a factor the default
functions from options("contrasts") are used.See Also
C, contr.helmert, contr.poly,
contr.sum, contr.treatment,
glm, aov, lm.Examples
example(factor)
(fff <- factor(ff))
contrasts(fff) # treatment
contrasts(C(fff, sum))