tests/testthat/test-add_columns.R

In tjmahr/polypoly: Helper Functions for Orthogonal Polynomials

context("add_columns")

test_that("Throws error when a column already exists", {
  df <- cbind(x = 1:10, as.data.frame(poly(1:10, 3)))
  df <- stats::setNames(df, c("x", "x1", "x2", "x3"))

  expect_error(poly_add_columns(df, x, degree = 3))
  df$x1 <- NULL
  expect_error(poly_add_columns(df, x, degree = 3))
})

test_that("Throws error when data column does not exist", {
  df <- cbind(x = 1:10, as.data.frame(poly(1:10, 3)))
  df <- stats::setNames(df, c("x", "x1", "x2", "x3"))

  expect_error(poly_add_columns(df, y, degree = 3))
})

test_that("Prefixes work", {
  df <- cbind(x = 1:10, as.data.frame(poly(1:10, 3)))
  df <- stats::setNames(df, c("x", "x1", "x2", "x3"))

  result <- poly_add_columns(df, x, degree = 3, prefix = "ox_")

  expect_named(result, c(names(df), "ox_1", "ox_2", "ox_3"))
})

test_that("Values don't change", {
  df <- cbind(x = 1:10, as.data.frame(poly(1:10, 3)))
  df <- stats::setNames(df, c("x", "x1", "x2", "x3"))

  result <- poly_add_columns(df, x, degree = 3, prefix = "ox_")

  expect_equal(result$x1, result$ox_1)
  expect_equal(result$x2, result$ox_2)
  expect_equal(result$x3, result$ox_3)
})

test_that("Repeated values get the same polynomial", {
  xs <- rnorm(10)
  df_rep <- data.frame(x = rep(xs, 3))
  result <- poly_add_columns(df_rep, x, degree = 3)

  expect_true(length(unique(result$x1)) == length(unique(result$x)))

  # Manually polynomials for unique xs should match those in the dataframe
  df_single <- data.frame(x = xs)
  result_single <- poly_add_columns(df_single, x, degree = 3, prefix = "s")
  df_both <- merge(result, result_single, by = "x")

  expect_equal(df_both$x1, df_both$s1)
  expect_equal(df_both$x2, df_both$s2)
  expect_equal(df_both$x3, df_both$s3)
})

test_that("Optional rescaling works", {
  df <- data.frame(x = rep(rnorm(10), 3))
  result <- poly_add_columns(df, x, degree = 3, scale_width = 4)

  expect_equal(max(result$x1) - min(result$x1), 4)
})

test_that("Optional rescaling works for repeated values", {
  xs <- rnorm(10)
  df_rep <- data.frame(x = rep(xs, 3))
  result <- poly_add_columns(df_rep, x, degree = 3, scale_width = 1)

  expect_true(length(unique(result$x1)) == length(unique(result$x)))

  # Manually polynomials for unique xs should match those in the dataframe
  df_single <- data.frame(x = xs)
  result_single <- poly_add_columns(df_single, x, degree = 3, prefix = "s",
                                    scale_width = 1)
  df_both <- merge(result, result_single, by = "x")

  expect_equal(df_both$x1, df_both$s1)
  expect_equal(df_both$x2, df_both$s2)
  expect_equal(df_both$x3, df_both$s3)
})


test_that("Correlations are sound in dataframes", {
  xs <- rnorm(50)
  df_rep <- data.frame(x = rep(xs, 5))
  result <- poly_add_columns(df_rep, x, degree = 3)

  cor_mat <- cor(result[, c("x1", "x2", "x3"), drop = FALSE])
  expect_equivalent(zapsmall(cor_mat), diag(3))
})


test_that("NAs can be handled.", {
  xs <- c(NA_real_, NA_real_, rnorm(5))
  df_rep <- data.frame(x = xs)

  expect_error(
    poly_add_columns(df_rep, x, degree = 3),
    regexp = "NA values found"
  )

  expect_error(
    poly_add_columns(df_rep, x, degree = 3, na_values = "error"),
    regexp = "NA values found"
  )

  x <- expect_warning(
    poly_add_columns(df_rep, x, degree = 3, na_values = "warn"),
    regexp = "NA values found"
  )
  expect_true(is.na(x[["x1"]][2]))

  y <- expect_silent(
    poly_add_columns(df_rep, x, degree = 3, na_values = "allow")
  )
  expect_true(is.na(y[["x1"]][2]))
})