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))