BUG: lzma is a required part of python, make it optional

doc/source/whatsnew/v0.25.1.rst

@@ -103,7 +103,6 @@ MultiIndex
 
 I/O
 ^^^
-
 - Avoid calling ``S3File.s3`` when reading parquet, as this was removed in s3fs version 0.3.0 (:issue:`27756`)
 -
 -
@@ -160,6 +159,15 @@ Other
 -
 -
 
+I/O and LZMA
+~~~~~~~~~~~~
+
+- Issue: Some users may unknowingly have an incomplete Python installation, which lacks the `lzma` module from the standard library. In this case, `import pandas` fails due to an `ImportError`; (:issue: `27575`)
+- Change: Pandas will now warn, rather than raising an `ImportError` if the `lzma` module is not present. Any subsequent attempt to use `lzma` methods will raise a `RuntimeError`;
+- Possible Fix: Ensure you have the necessary libraries and reinstall Python;
+- Example: On MacOS, installing Python with `pyenv` may lead to an incomplete Python installation due to unmet system dependencies at compilation time (like `xz`). Compilation will succeed, but Python might fail at run time.
+
+
 .. _whatsnew_0.251.contributors:
 
 Contributors

pandas/_libs/parsers.pyx

@@ -2,7 +2,6 @@
 # See LICENSE for the license
 import bz2
 import gzip
-import lzma
 import os
 import sys
 import time
@@ -59,9 +58,12 @@ from pandas.core.arrays import Categorical
 from pandas.core.dtypes.concat import union_categoricals
 import pandas.io.common as icom
 
+from pandas.compat import import_lzma
 from pandas.errors import (ParserError, DtypeWarning,
                            EmptyDataError, ParserWarning)
 
+lzma = import_lzma()
+
 # Import CParserError as alias of ParserError for backwards compatibility.
 # Ultimately, we want to remove this import. See gh-12665 and gh-14479.
 CParserError = ParserError
@@ -644,6 +646,11 @@ cdef class TextReader:
                     raise ValueError('Multiple files found in compressed '
                                      'zip file %s', str(zip_names))
             elif self.compression == 'xz':
+                if lzma is None:
+                    raise RuntimeError("lzma module not available. "
+                                       "A Python re-install with the proper "
+                                       "dependencies might be required to "
+                                       "solve this issue.")
                 if isinstance(source, str):
                     source = lzma.LZMAFile(source, 'rb')
                 else:

pandas/compat/__init__.py

@@ -10,6 +10,7 @@
 import platform
 import struct
 import sys
+import warnings
 
 PY35 = sys.version_info[:2] == (3, 5)
 PY36 = sys.version_info >= (3, 6)
@@ -65,3 +66,16 @@ def is_platform_mac():
 
 def is_platform_32bit():
     return struct.calcsize("P") * 8 < 64
+
+
+def import_lzma():
+    try:
+        import lzma
+
+        return lzma
+    except ImportError:
+        msg = (
+            "Could not import the lzma module. Your installed Python is incomplete. "
+            "Attempting to use `lzma` compression will result in a RuntimeError."
+        )
+        warnings.warn(msg)

pandas/io/common.py

@@ -6,7 +6,6 @@
 import gzip
 from http.client import HTTPException  # noqa
 from io import BytesIO
-import lzma
 import mmap
 import os
 import pathlib
@@ -23,6 +22,7 @@
 from urllib.request import pathname2url, urlopen
 import zipfile
 
+from pandas.compat import import_lzma
 from pandas.errors import (  # noqa
     AbstractMethodError,
     DtypeWarning,
@@ -35,6 +35,8 @@
 
 from pandas._typing import FilePathOrBuffer
 
+lzma = import_lzma()
+
 # gh-12665: Alias for now and remove later.
 CParserError = ParserError
 
@@ -395,7 +397,15 @@ def _get_handle(
 
         # XZ Compression
         elif compression == "xz":
-            f = lzma.LZMAFile(path_or_buf, mode)
+            if lzma is None:
+                raise RuntimeError(
+                    "lzma module not available. "
+                    "A Python re-install with the proper "
+                    "dependencies might be required to "
+                    "solve this issue."
+                )
+            else:
+                f = lzma.LZMAFile(path_or_buf, mode)
 
         # Unrecognized Compression
         else:

pandas/tests/io/test_compression.py

@@ -1,5 +1,7 @@
 import contextlib
 import os
+import subprocess
+import textwrap
 import warnings
 
 import pytest
@@ -125,3 +127,15 @@ def test_compression_warning(compression_only):
         with tm.assert_produces_warning(RuntimeWarning, check_stacklevel=False):
             with f:
                 df.to_csv(f, compression=compression_only)
+
+
+def test_with_missing_lzma():
+    # https://github.com/pandas-dev/pandas/issues/27575
+    code = textwrap.dedent(
+        """\
+        import sys
+        sys.modules['lzma'] = None
+        import pandas
+        """
+    )
+    subprocess.check_output(["python", "-c", code])

pandas/tests/io/test_pickle.py

@@ -13,7 +13,6 @@
 import bz2
 import glob
 import gzip
-import lzma
 import os
 import pickle
 import shutil
@@ -22,14 +21,16 @@
 
 import pytest
 
-from pandas.compat import is_platform_little_endian
+from pandas.compat import import_lzma, is_platform_little_endian
 
 import pandas as pd
 from pandas import Index
 import pandas.util.testing as tm
 
 from pandas.tseries.offsets import Day, MonthEnd
 
+lzma = import_lzma()
+
 
 @pytest.fixture(scope="module")
 def current_pickle_data():
@@ -270,7 +271,15 @@ def compress_file(self, src_path, dest_path, compression):
             with zipfile.ZipFile(dest_path, "w", compression=zipfile.ZIP_DEFLATED) as f:
                 f.write(src_path, os.path.basename(src_path))
         elif compression == "xz":
-            f = lzma.LZMAFile(dest_path, "w")
+            if lzma is None:
+                raise RuntimeError(
+                    "lzma module not available. "
+                    "A Python re-install with the proper "
+                    "dependencies might be required to "
+                    "solve this issue."
+                )
+            else:
+                f = lzma.LZMAFile(dest_path, "w")
         else:
             msg = "Unrecognized compression type: {}".format(compression)
             raise ValueError(msg)

pandas/util/testing.py

@@ -5,7 +5,6 @@
 from functools import wraps
 import gzip
 import http.client
-import lzma
 import os
 import re
 from shutil import rmtree
@@ -26,7 +25,7 @@
 )
 
 import pandas._libs.testing as _testing
-from pandas.compat import raise_with_traceback
+from pandas.compat import import_lzma, raise_with_traceback
 
 from pandas.core.dtypes.common import (
     is_bool,
@@ -70,6 +69,8 @@
 from pandas.io.common import urlopen
 from pandas.io.formats.printing import pprint_thing
 
+lzma = import_lzma()
+
 N = 30
 K = 4
 _RAISE_NETWORK_ERROR_DEFAULT = False
@@ -211,7 +212,15 @@ def decompress_file(path, compression):
     elif compression == "bz2":
         f = bz2.BZ2File(path, "rb")
     elif compression == "xz":
-        f = lzma.LZMAFile(path, "rb")
+        if lzma is None:
+            raise RuntimeError(
+                "lzma module not available. "
+                "A Python re-install with the proper "
+                "dependencies might be required to "
+                "solve this issue."
+            )
+        else:
+            f = lzma.LZMAFile(path, "rb")
     elif compression == "zip":
         zip_file = zipfile.ZipFile(path)
         zip_names = zip_file.namelist()
@@ -264,9 +273,15 @@ def write_to_compressed(compression, path, data, dest="test"):
 
         compress_method = bz2.BZ2File
     elif compression == "xz":
-        import lzma
-
-        compress_method = lzma.LZMAFile
+        if lzma is None:
+            raise RuntimeError(
+                "lzma module not available. "
+                "A Python re-install with the proper "
+                "dependencies might be required to "
+                "solve this issue."
+            )
+        else:
+            compress_method = lzma.LZMAFile
     else:
         msg = "Unrecognized compression type: {}".format(compression)
         raise ValueError(msg)