Compat with older Python

.github/workflows/CI.yml

@@ -41,6 +41,10 @@ jobs:
             python-version: '3.12'
             os: ubuntu-latest
             test-id: include
+          - julia-version: '1'
+            python-version: '3.8'
+            os: ubuntu-latest
+            test-id: include
 
     steps:
       - uses: actions/checkout@v4

pyproject.toml

@@ -11,7 +11,7 @@ authors = [
 description = "Simple and efficient symbolic regression"
 readme = {file = "README.md", content-type = "text/markdown"}
 license = {file = "LICENSE"}
-requires-python = ">=3.10"
+requires-python = ">=3.8"
 classifiers = [
     "Programming Language :: Python :: 3",
     "Operating System :: OS Independent",
@@ -39,7 +39,7 @@ dev = [
     "mypy>=1,<2",
     "nbval>=0.11,<0.12",
     "pandas-stubs",
-    "pre-commit>=3.7,<5",
+    "pre-commit>=3.0,<5",
     "pytest-cov>=5,<7",
     "pytest>=8,<9",
     "tensorboard>=2,<3",

pysr/__init__.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import logging
 import os
 

pysr/denoising.py

@@ -1,5 +1,7 @@
 """Functions for denoising data during preprocessing."""
 
+from __future__ import annotations
+
 from typing import cast
 
 import numpy as np

pysr/export.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import copy
 from collections.abc import Callable
 

pysr/export_latex.py

@@ -1,5 +1,7 @@
 """Functions to help export PySR equations to LaTeX."""
 
+from __future__ import annotations
+
 import pandas as pd
 import sympy  # type: ignore
 from sympy.printing.latex import LatexPrinter  # type: ignore

pysr/export_numpy.py

@@ -1,5 +1,7 @@
 """Code for exporting discovered expressions to numpy"""
 
+from __future__ import annotations
+
 import warnings
 
 import numpy as np

pysr/export_sympy.py

@@ -1,5 +1,7 @@
 """Define utilities to export to sympy"""
 
+from __future__ import annotations
+
 from collections.abc import Callable
 
 import sympy  # type: ignore

pysr/expression_specs.py

@@ -1,7 +1,9 @@
+from __future__ import annotations
+
 import copy
 from abc import ABC, abstractmethod
 from textwrap import dedent
-from typing import TYPE_CHECKING, Any, NewType, TypeAlias, overload
+from typing import TYPE_CHECKING, Any, NewType, overload
 
 import numpy as np
 import pandas as pd
@@ -10,6 +12,11 @@
 from .julia_helpers import jl_array
 from .julia_import import AnyValue, SymbolicRegression, jl
 
+try:
+    from typing import TypeAlias
+except ImportError:
+    from typing_extensions import TypeAlias
+
 # For type checking purposes
 if TYPE_CHECKING:
     from .sr import PySRRegressor  # pragma: no cover

pysr/feature_selection.py

@@ -1,5 +1,7 @@
 """Functions for doing feature selection during preprocessing."""
 
+from __future__ import annotations
+
 import logging
 from typing import cast
 

pysr/julia_extensions.py

@@ -1,5 +1,7 @@
 """This file installs and loads extensions for SymbolicRegression."""
 
+from __future__ import annotations
+
 from typing import Literal
 
 from .julia_import import Pkg, jl

pysr/julia_registry_helpers.py

@@ -1,5 +1,7 @@
 """Utilities for managing Julia registry preferences during package operations."""
 
+from __future__ import annotations
+
 import os
 import warnings
 from collections.abc import Callable

pysr/logger_specs.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from abc import ABC, abstractmethod
 from dataclasses import dataclass
 from typing import Any

pysr/sr.py

@@ -1,5 +1,7 @@
 """Define the PySRRegressor scikit-learn interface."""
 
+from __future__ import annotations
+
 import copy
 import logging
 import os
@@ -13,7 +15,7 @@
 from io import StringIO
 from multiprocessing import cpu_count
 from pathlib import Path
-from typing import Any, Literal, cast
+from typing import Any, List, Literal, Tuple, Union, cast
 
 import numpy as np
 import pandas as pd
@@ -94,7 +96,7 @@ def _process_constraints(
                 )
             constraints[op] = (-1, -1)
 
-        constraint_tuple = cast(tuple[int, int], constraints[op])
+        constraint_tuple = cast(Tuple[int, int], constraints[op])
         if op in ["plus", "sub", "+", "-"]:
             if constraint_tuple[0] != constraint_tuple[1]:
                 raise NotImplementedError(
@@ -1313,7 +1315,7 @@ def julia_options_(self):
     def julia_state_(self):
         """The deserialized state."""
         return cast(
-            tuple[VectorValue, AnyValue] | None,
+            Union[Tuple[VectorValue, AnyValue], None],
             jl_deserialize(self.julia_state_stream_),
         )
 
@@ -1640,7 +1642,7 @@ def _validate_data_X_y(self, X: Any, y: Any) -> tuple[ndarray, ndarray]:
             raw_out = self._validate_data(X=X, y=y, reset=True, multi_output=True)  # type: ignore
         else:
             raw_out = validate_data(self, X=X, y=y, reset=True, multi_output=True)  # type: ignore
-        return cast(tuple[ndarray, ndarray], raw_out)
+        return cast(Tuple[ndarray, ndarray], raw_out)
 
     def _validate_data_X(self, X: Any) -> ndarray:
         if OLD_SKLEARN:
@@ -2629,7 +2631,7 @@ def get_hof(self, search_output=None) -> pd.DataFrame | list[pd.DataFrame]:
 
         _validate_export_mappings(self.extra_jax_mappings, self.extra_torch_mappings)
 
-        equation_file_contents = cast(list[pd.DataFrame], self.equation_file_contents_)
+        equation_file_contents = cast(List[pd.DataFrame], self.equation_file_contents_)
 
         ret_outputs = [
             pd.concat(

pysr/utils.py

@@ -4,15 +4,15 @@
 import inspect
 import re
 from pathlib import Path
-from typing import Any, TypeVar
+from typing import Any, List, TypeVar, Union
 
 from numpy import ndarray
 from sklearn.utils.validation import _check_feature_names_in  # type: ignore
 
 T = TypeVar("T", bound=Any)
 
-ArrayLike = ndarray | list[T]
-PathLike = str | Path
+ArrayLike = Union[ndarray, List[T]]
+PathLike = Union[str, Path]
 
 
 _regexp_im = re.compile(r"\b(\d+\.\d+)im\b")