tests/testthat/test-functions.R

In simisc/splintr: Natural Cubic SPLines with Interpretable INTercepts

library(splines)
library(splintr)

b0 <- ns(women$height, df = 5)
b1 <- splintr(women$height, df = 5)
b2 <- splintr(women$height, df = 5, centre = 67.23)

test_that("bases are zero at centre", {
  expect_equal(as.numeric(predict(b1, newx = 0)), rep(0, 5))
  expect_equal(as.numeric(predict(b2, newx = 67.23)), rep(0, 5))
})

m0 <- lm(weight ~ ns(height, df = 5), data = women)
m1 <- lm(weight ~ splintr(height, df = 5), data = women)
m2 <- lm(weight ~ splintr(height, df = 5, centre = 67.23), data = women)

test_that("models have the same deviance", {
  expect_equal(deviance(m0), deviance(m1))
  expect_equal(deviance(m0), deviance(m2))
})

test_that("models have the same residuals", {
  expect_equal(resid(m0), resid(m1))
  expect_equal(resid(m0), resid(m2))
})

test_that("models generate the same predictions", {
  expect_equal(predict(m0), predict(m1))
  expect_equal(predict(m0), predict(m2))
})