Revert "feat[python]!: Update Expr.sample signature and change rand…

…om seeding (#4641)" (#4643)

This reverts commit 50eba3d.

py-polars/polars/internals/dataframe/frame.py

@@ -2,7 +2,6 @@
 from __future__ import annotations
 
 import os
-import random
 import sys
 from io import BytesIO, IOBase, StringIO
 from pathlib import Path
@@ -5615,7 +5614,7 @@ def sample(
             Shuffle the order of sampled data points.
         seed
             Seed for the random number generator. If set to None (default), a random
-            seed is generated using the ``random`` module.
+            seed is used.
 
         Examples
         --------
@@ -5642,9 +5641,6 @@ def sample(
         if n is not None and frac is not None:
             raise ValueError("cannot specify both `n` and `frac`")
 
-        if seed is None:
-            seed = random.randint(0, 10000)
-
         if n is None and frac is not None:
             return self._from_pydf(
                 self._df.sample_frac(frac, with_replacement, shuffle, seed)

py-polars/polars/internals/expr/expr.py

@@ -4,6 +4,7 @@
 import random
 from datetime import date, datetime
 from typing import TYPE_CHECKING, Any, Callable, Sequence
+from warnings import warn
 
 from polars import internals as pli
 from polars.datatypes import (
@@ -5393,22 +5394,20 @@ def shuffle(self, seed: int | None = None) -> Expr:
             seed = random.randint(0, 10000)
         return wrap_expr(self._pyexpr.shuffle(seed))
 
+    @deprecated_alias(fraction="frac")
     def sample(
         self,
-        n: int | None = None,
         frac: float | None = None,
-        with_replacement: bool = False,
+        with_replacement: bool = True,
         shuffle: bool = False,
         seed: int | None = None,
+        n: int | None = None,
     ) -> Expr:
         """
         Sample from this expression.
 
         Parameters
         ----------
-        n
-            Number of items to return. Cannot be used with `frac`. Defaults to 1 if
-            `frac` is None.
         frac
             Fraction of items to return. Cannot be used with `n`.
         with_replacement
@@ -5417,7 +5416,9 @@ def sample(
             Shuffle the order of sampled data points.
         seed
             Seed for the random number generator. If set to None (default), a random
-            seed is generated using the ``random`` module.
+            seed is used.
+        n
+            Number of items to return. Cannot be used with `frac`.
 
         Examples
         --------
@@ -5437,20 +5438,25 @@ def sample(
         └─────┘
 
         """
+        warn(
+            "The function signature for Expr.sample will change in a future"
+            " version. Explicitly set `frac` and `with_replacement` using keyword"
+            " arguments to retain the same behaviour.",
+            FutureWarning,
+            stacklevel=2,
+        )
+
         if n is not None and frac is not None:
             raise ValueError("cannot specify both `n` and `frac`")
 
-        if seed is None:
-            seed = random.randint(0, 10000)
-
-        if frac is not None:
-            return wrap_expr(
-                self._pyexpr.sample_frac(frac, with_replacement, shuffle, seed)
-            )
+        if n is not None and frac is None:
+            return wrap_expr(self._pyexpr.sample_n(n, with_replacement, shuffle, seed))
 
-        if n is None:
-            n = 1
-        return wrap_expr(self._pyexpr.sample_n(n, with_replacement, shuffle, seed))
+        if frac is None:
+            frac = 1.0
+        return wrap_expr(
+            self._pyexpr.sample_frac(frac, with_replacement, shuffle, seed)
+        )
 
     def ewm_mean(
         self,

py-polars/polars/internals/series/series.py

@@ -3554,7 +3554,7 @@ def sample(
             Shuffle the order of sampled data points.
         seed
             Seed for the random number generator. If set to None (default), a random
-            seed is generated using the ``random`` module.
+            seed is used.
 
         Examples
         --------
@@ -3568,6 +3568,15 @@ def sample(
         ]
 
         """
+        if n is not None and frac is not None:
+            raise ValueError("cannot specify both `n` and `frac`")
+
+        if n is None and frac is not None:
+            return wrap_s(self._s.sample_frac(frac, with_replacement, shuffle, seed))
+
+        if n is None:
+            n = 1
+        return wrap_s(self._s.sample_n(n, with_replacement, shuffle, seed))
 
     def peak_max(self) -> Series:
         """

py-polars/src/series.rs

@@ -558,6 +558,34 @@ impl PySeries {
         self.series.has_validity()
     }
 
+    pub fn sample_n(
+        &self,
+        n: usize,
+        with_replacement: bool,
+        shuffle: bool,
+        seed: Option<u64>,
+    ) -> PyResult<Self> {
+        let s = self
+            .series
+            .sample_n(n, with_replacement, shuffle, seed)
+            .map_err(PyPolarsErr::from)?;
+        Ok(s.into())
+    }
+
+    pub fn sample_frac(
+        &self,
+        frac: f64,
+        with_replacement: bool,
+        shuffle: bool,
+        seed: Option<u64>,
+    ) -> PyResult<Self> {
+        let s = self
+            .series
+            .sample_frac(frac, with_replacement, shuffle, seed)
+            .map_err(PyPolarsErr::from)?;
+        Ok(s.into())
+    }
+
     pub fn series_equal(&self, other: &PySeries, null_equal: bool, strict: bool) -> bool {
         if strict {
             self.series.eq(&other.series)

py-polars/tests/test_exprs.py

@@ -1,9 +1,9 @@
 from __future__ import annotations
 
-import random
 from typing import cast
 
 import numpy as np
+import pytest
 
 import polars as pl
 from polars.testing import assert_series_equal, verify_series_and_expr_api
@@ -94,6 +94,7 @@ def test_count_expr() -> None:
     assert out["count"].to_list() == [4, 1]
 
 
+@pytest.mark.filterwarnings("ignore::FutureWarning")
 def test_sample() -> None:
     a = pl.Series("a", range(0, 20))
     out = pl.select(
@@ -108,13 +109,6 @@ def test_sample() -> None:
     assert out.to_list() != out.sort().to_list()
     assert out.unique().shape == (10,)
 
-    # Setting random.seed should lead to reproducible results
-    random.seed(1)
-    result1 = pl.select(pl.lit(a).sample(n=10)).to_series()
-    random.seed(1)
-    result2 = pl.select(pl.lit(a).sample(n=10)).to_series()
-    assert result1.series_equal(result2)
-
 
 def test_map_alias() -> None:
     out = pl.DataFrame({"foo": [1, 2, 3]}).select(