context("Lag")
test_that("Lag with Sequential Groups", {
x <- rep(1:5, 2)
f <- gl(2, 5)
expect_equal(Lag(x, 1, f), c(NA, 1, 2, 3, 4, NA, 1, 2, 3, 4))
expect_equal(Lag(x, -1, f), c(2, 3, 4, 5, NA, 2, 3, 4, 5, NA))
expect_equal(Lag(x, 0, f), x)
})
test_that("Lag with Grouped Groups", {
x <- rep(1:5, each = 2)
f <- gl(5, 2)
expect_equal(Lag(x, 1, f), c(NA, 1, NA, 2, NA, 3, NA, 4, NA, 5))
expect_equal(Lag(x, -1, f), c(1, NA, 2, NA, 3, NA, 4, NA, 5, NA))
expect_equal(Lag(x, 0, f), x)
})
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