contrasts {base} | R Documentation |
contrasts(x) contrasts(x) <- ctr
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. |
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.
C
, contr.helmert
, contr.poly
,
contr.sum
, contr.treatment
,
glm
, aov
, lm
.
example(factor) (fff <- factor(ff)) contrasts(fff) # treatment contrasts(C(fff, sum))