perf(python): remove pandas imports (#5286)

py-polars/polars/convert.py

@@ -2,6 +2,7 @@
 
 from typing import TYPE_CHECKING, Any, Mapping, Sequence, overload
 
+from polars.import_check import _PANDAS_AVAILABLE, pandas_mod
 from polars.internals import DataFrame, Series
 
 try:
@@ -18,14 +19,12 @@
 except ImportError:
     _PYARROW_AVAILABLE = False
 
-try:
-    import pandas as pd
-
-    _PANDAS_AVAILABLE = True
-except ImportError:
-    _PANDAS_AVAILABLE = False
 
 if TYPE_CHECKING:
+    try:  # noqa: SIM105
+        import pandas as pd
+    except ImportError:
+        pass
     from polars.internals.type_aliases import Orientation
 
 
@@ -364,6 +363,7 @@ def from_pandas(
     if not _PANDAS_AVAILABLE:
         raise ImportError("'pandas' is required when using from_pandas().")
 
+    pd = pandas_mod()
     if isinstance(df, (pd.Series, pd.DatetimeIndex)):
         return Series._from_pandas("", df, nan_to_none=nan_to_none)
     elif isinstance(df, pd.DataFrame):

py-polars/polars/import_check.py

@@ -0,0 +1,15 @@
+import importlib.util
+from typing import Any
+
+
+def pandas_mod() -> Any:
+    import pandas as pd
+
+    return pd
+
+
+def pkg_is_available(name: str) -> bool:
+    return importlib.util.find_spec(name) is not None
+
+
+_PANDAS_AVAILABLE = pkg_is_available("pandas")

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

@@ -40,6 +40,7 @@
     py_type_to_dtype,
 )
 from polars.exceptions import NoRowsReturned, TooManyRowsReturned
+from polars.import_check import _PANDAS_AVAILABLE, pandas_mod
 from polars.internals.construction import (
     arrow_to_pydf,
     dict_to_pydf,
@@ -88,13 +89,6 @@
 except ImportError:
     _PYARROW_AVAILABLE = False
 
-try:
-    import pandas as pd
-
-    _PANDAS_AVAILABLE = True
-except ImportError:
-    _PANDAS_AVAILABLE = False
-
 if sys.version_info >= (3, 8):
     from typing import Literal
 else:
@@ -106,6 +100,11 @@
     from typing_extensions import TypeAlias
 
 if TYPE_CHECKING:
+    try:  # noqa: SIM105
+        import pandas as pd
+    except ImportError:
+        pass
+
     from polars.internals.type_aliases import (
         AsofJoinStrategy,
         AvroCompression,
@@ -303,7 +302,7 @@ def __init__(
         elif isinstance(data, pli.Series):
             self._df = series_to_pydf(data, columns=columns)
 
-        elif _PANDAS_AVAILABLE and isinstance(data, pd.DataFrame):
+        elif _PANDAS_AVAILABLE and isinstance(data, pandas_mod().DataFrame):
             if not _PYARROW_AVAILABLE:  # pragma: no cover
                 raise ImportError(
                     "'pyarrow' is required for converting a pandas DataFrame to a"

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

@@ -35,6 +35,7 @@
     py_type_to_dtype,
     supported_numpy_char_code,
 )
+from polars.import_check import _PANDAS_AVAILABLE, pandas_mod
 from polars.internals.construction import (
     arrow_to_pyseries,
     numpy_to_pyseries,
@@ -83,14 +84,13 @@
 except ImportError:
     _PYARROW_AVAILABLE = False
 
-try:
-    import pandas as pd
-
-    _PANDAS_AVAILABLE = True
-except ImportError:
-    _PANDAS_AVAILABLE = False
 
 if TYPE_CHECKING:
+    try:  # noqa: SIM105
+        import pandas as pd
+    except ImportError:
+        pass
+
     from polars.internals.type_aliases import (
         ComparisonOperator,
         FillNullStrategy,
@@ -236,7 +236,9 @@ def __init__(
             self._s = sequence_to_pyseries(
                 name, values, dtype=dtype, strict=strict, dtype_if_empty=dtype_if_empty
             )
-        elif _PANDAS_AVAILABLE and isinstance(values, (pd.Series, pd.DatetimeIndex)):
+        elif _PANDAS_AVAILABLE and isinstance(
+            values, (pandas_mod().Series, pandas_mod().DatetimeIndex)
+        ):
             self._s = pandas_to_pyseries(name, values)
         else:
             raise ValueError("Series constructor not called properly.")