tests/testthat/test-sample.R

In MilesMcBain/wisegroup: Safe grouping wrappers for group-aware tidy functions

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context("Sample")

test_that("grouped sample respects weight", {
  df2 <- tibble::tibble(
    x = rep(1:2, 100),
    y = rep(c(0, 1), 100),
    g = rep(1:2, each = 100)
  )

  grp <- df2 %>% dplyr::group_by(g)

  # error message from base R
  expect_error(sample_n(grp, nrow(df2) / 2, weight = y))
  expect_equal(sample_n(grp, 1, weight = y)$x, c(2, 2))

  # error message from base R
  expect_error(sample_frac(grp, 1, weight = y))
  expect_equal(sample_frac(grp, 0.5, weight = y)$x, rep(2, nrow(df2) / 2))
})

test_that("grouped sample accepts NULL weight from variable (for saeSim)", {
  df <- tibble::tibble(
    x = rep(1:2, 10),
    y = rep(c(0, 1), 10),
    g = rep(1:2, each = 10)
  )

  weight <- NULL

  expect_error(sample_n(df, nrow(df), weight = weight), NA)
  expect_error(sample_frac(df, weight = weight), NA)

  grp <- df %>% dplyr::group_by(g)

  expect_error(sample_n(grp, nrow(df) / 2, weight = weight), NA)
  expect_error(sample_frac(grp, weight = weight), NA)
})

test_that("sample_n and sample_frac can call n() (#3413)", {
  df <- tibble::tibble(
    x = rep(1:2, 10),
    y = rep(c(0, 1), 10),
    g = rep(1:2, each = 10)
  )
  gdf <- dplyr::group_by(df, g)

  expect_equal(sample_n(df, dplyr::n()), df)
  expect_equal(sample_n(gdf, dplyr::n()), gdf)

  expect_equal(nrow(sample_n(df, dplyr::n()-2L)), nrow(df)-2)
  expect_equal(nrow(sample_n(gdf, dplyr::n()-2L)), nrow(df)-4)
})

test_that("sample_n and sample_frac handles lazy grouped data frames (#3380)", {
  df1 <- data.frame(x = 1:10, y = rep(1:2, each=5))
  df2 <- data.frame(x = 6:15, z = 1:10)
  res <- df1 %>% dplyr::group_by(y) %>% dplyr::anti_join(df2, by="x") %>% sample_n(1)
  expect_equal(nrow(res), 1L)

  res <- df1 %>% dplyr::group_by(y) %>% dplyr::anti_join(df2, by="x") %>% sample_frac(0.2)
  expect_equal(nrow(res), 1L)
})