orth_polynomial_code {contrastable} | R Documentation |
Orthogonal Polynomial code
Description
Wrapper around stats::contr.poly()
. You can also use polynomial_code()
as an alias.
Usage
orth_polynomial_code(n)
polynomial_code(n)
Arguments
n |
Integer umber of factor levels to compute contrasts for. |
Details
For n levels of factors where k in 1:n, generate a matrix with n-1 comparisons where each comparison looks for a polynomial trend of degree k where each polynomial is independent of the others.
Value
A contrast matrix with dimensions n rows and (n-1) columns.
Examples
mydf <- data.frame(
grp = rep(c("a", "b", "c", "d"), each = 2000),
val = c(
rnorm(200, 2, 1),
rnorm(200, 5, 1),
rnorm(200, 7.5, 1),
rnorm(200, 15, 1)
)
) |>
set_contrasts(grp ~ polynomial_code)
stats::lm(val ~ grp, data = mydf)
[Package contrastable version 1.0.2 Index]