8th day of python challenges 111-117

venv/lib/python3.6/site-packages/pandas/compat/_optional.py

@@ -0,0 +1,111 @@
+import distutils.version
+import importlib
+import types
+import warnings
+
+# Update install.rst when updating versions!
+
+VERSIONS = {
+    "bs4": "4.6.0",
+    "bottleneck": "1.2.1",
+    "fastparquet": "0.2.1",
+    "gcsfs": "0.2.2",
+    "lxml.etree": "3.8.0",
+    "matplotlib": "2.2.2",
+    "numexpr": "2.6.2",
+    "odfpy": "1.3.0",
+    "openpyxl": "2.4.8",
+    "pandas_gbq": "0.8.0",
+    "pyarrow": "0.9.0",
+    "pytables": "3.4.2",
+    "s3fs": "0.0.8",
+    "scipy": "0.19.0",
+    "sqlalchemy": "1.1.4",
+    "tables": "3.4.2",
+    "xarray": "0.8.2",
+    "xlrd": "1.1.0",
+    "xlwt": "1.2.0",
+    "xlsxwriter": "0.9.8",
+}
+
+message = (
+    "Missing optional dependency '{name}'. {extra} "
+    "Use pip or conda to install {name}."
+)
+version_message = (
+    "Pandas requires version '{minimum_version}' or newer of '{name}' "
+    "(version '{actual_version}' currently installed)."
+)
+
+
+def _get_version(module: types.ModuleType) -> str:
+    version = getattr(module, "__version__", None)
+    if version is None:
+        # xlrd uses a capitalized attribute name
+        version = getattr(module, "__VERSION__", None)
+
+    if version is None:
+        raise ImportError("Can't determine version for {}".format(module.__name__))
+    return version
+
+
+def import_optional_dependency(
+    name: str, extra: str = "", raise_on_missing: bool = True, on_version: str = "raise"
+):
+    """
+    Import an optional dependency.
+
+    By default, if a dependency is missing an ImportError with a nice
+    message will be raised. If a dependency is present, but too old,
+    we raise.
+
+    Parameters
+    ----------
+    name : str
+        The module name. This should be top-level only, so that the
+        version may be checked.
+    extra : str
+        Additional text to include in the ImportError message.
+    raise_on_missing : bool, default True
+        Whether to raise if the optional dependency is not found.
+        When False and the module is not present, None is returned.
+    on_version : str {'raise', 'warn'}
+        What to do when a dependency's version is too old.
+
+        * raise : Raise an ImportError
+        * warn : Warn that the version is too old. Returns None
+        * ignore: Return the module, even if the version is too old.
+          It's expected that users validate the version locally when
+          using ``on_version="ignore"`` (see. ``io/html.py``)
+
+    Returns
+    -------
+    maybe_module : Optional[ModuleType]
+        The imported module, when found and the version is correct.
+        None is returned when the package is not found and `raise_on_missing`
+        is False, or when the package's version is too old and `on_version`
+        is ``'warn'``.
+    """
+    try:
+        module = importlib.import_module(name)
+    except ImportError:
+        if raise_on_missing:
+            raise ImportError(message.format(name=name, extra=extra)) from None
+        else:
+            return None
+
+    minimum_version = VERSIONS.get(name)
+    if minimum_version:
+        version = _get_version(module)
+        if distutils.version.LooseVersion(version) < minimum_version:
+            assert on_version in {"warn", "raise", "ignore"}
+            msg = version_message.format(
+                minimum_version=minimum_version, name=name, actual_version=version
+            )
+            if on_version == "warn":
+                warnings.warn(msg, UserWarning)
+                return None
+            elif on_version == "raise":
+                raise ImportError(msg)
+
+    return module