def mkdiff(cumcases: pl.Series) -> pl.Series:
return cumcases - cumcases.shift(1)
def test_shift():
a = Series("a", [1, 2, 3])
assert a.shift(1) == [None, 1, 2]
assert a.shift(-1) == [1, 2, None]
assert a.shift(-2) == [1, None, None]
def mkdiff(cumcases: pl.Series) -> pl.Series:
"""
Creates a new Series with differences per row
"""
return cumcases - cumcases.shift(1)
