def test_fold():
df = pl.DataFrame({"a": [1, 2, 3], "b": [1.0, 2.0, 3.0]})
out = df.lazy().select(pl.sum(["a", "b"])).collect()
assert out["sum"].series_equal(pl.Series("sum", [2, 4, 6]))
out = df.select(
pl.fold(acc=lit(0), f=lambda acc, x: acc + x,
exprs=pl.col("*")).alias("foo"))
assert out["foo"] == [2, 4, 6]
def test_fold_filter():
df = pl.DataFrame({"a": [1, 2, 3], "b": [0, 1, 2]})
out = df.filter(
pl.fold(
acc=pl.lit(True),
f=lambda a, b: a & b,
exprs=[col(c) > 1 for c in df.columns],
))
assert out.shape == (1, 2)
out = df.filter(
pl.fold(
acc=pl.lit(True),
f=lambda a, b: a | b,
exprs=[col(c) > 1 for c in df.columns],
))
assert out.shape == (3, 2)
def test_regex_in_filter() -> None:
df = pl.DataFrame(
{
"nrs": [1, 2, 3, None, 5],
"names": ["foo", "ham", "spam", "egg", None],
"flt": [1.0, None, 3.0, 1.0, None],
}
)
assert df.filter(
pl.fold(acc=False, f=lambda acc, s: acc | s, exprs=(pl.col("^nrs|flt*$") < 3))
).row(0) == (1, "foo", 1.0)
def test_fold() -> None:
df = pl.DataFrame({"a": [1, 2, 3], "b": [1.0, 2.0, 3.0]})
out = df.select([
pl.sum(["a", "b"]),
pl.max(["a", pl.col("b")**2]),
pl.min(["a", pl.col("b")**2]),
])
assert out["sum"].series_equal(pl.Series("sum", [2.0, 4.0, 6.0]))
assert out["max"].series_equal(pl.Series("max", [1.0, 4.0, 9.0]))
assert out["min"].series_equal(pl.Series("min", [1.0, 2.0, 3.0]))
out = df.select(
pl.fold(acc=lit(0), f=lambda acc, x: acc + x,
exprs=pl.col("*")).alias("foo"))
assert out["foo"] == [2, 4, 6]
def test_sum_to_one(self):
cols = [
"gravel_component",
"sand_component",
"clay_component",
"loam_component",
"peat_component",
"silt_component",
]
s = self.bore.df.select([
pl.fold(
pl.lit(0),
lambda a, b: a + b,
[
pl.when(pl.col(a) < 0).then(1 / len(cols)).otherwise(
pl.col(a)) for a in cols
],
).alias("sum")
])
self.assertTrue(np.all(np.isclose(s, 1)))
import polars as pl
from polars import col, lit
df = pl.DataFrame({"a": [1, 2, 3], "b": [0, 1, 2]})
out = df.filter(
pl.fold(acc=lit(True), f=lambda acc, x: acc & x, exprs=col("*") > 1))
import polars as pl
from polars import col, lit
df = pl.DataFrame({"a": [1, 2, 3], "b": [10, 20, 30]})
out = df.select(
pl.fold(acc=lit(0), f=lambda acc, x: acc + x, exprs=col("*")).alias("sum"))