Address remaining mypy errors in python package. (#7914)

Makefile

@@ -91,10 +91,7 @@ endif
 # If any of the dask tests failed, contributor won't see the other error.
 mypy:
 	cd python-package; \
-	mypy ./xgboost/dask.py && \
-	mypy ./xgboost/rabit.py && \
-	mypy ./xgboost/tracker.py && \
-	mypy ./xgboost/sklearn.py && \
+	mypy . && \
 	mypy ../demo/guide-python/external_memory.py && \
 	mypy ../demo/guide-python/categorical.py && \
 	mypy ../demo/guide-python/cat_in_the_dat.py && \

python-package/setup.py

@@ -335,11 +335,12 @@ if __name__ == '__main__':
               'scipy',
           ],
           ext_modules=[CMakeExtension('libxgboost')],
+          # error: expected "str": "Type[Command]"
           cmdclass={
-              'build_ext': BuildExt,
-              'sdist': Sdist,
-              'install_lib': InstallLib,
-              'install': Install
+              'build_ext': BuildExt,     # type: ignore
+              'sdist': Sdist,            # type: ignore
+              'install_lib': InstallLib,  # type: ignore
+              'install': Install          # type: ignore
           },
           extras_require={
               'pandas': ['pandas'],

python-package/xgboost/compat.py

@@ -8,12 +8,10 @@ import importlib.util
 import logging
 import numpy as np
 
-from xgboost._typing import CStrPtr
-
 assert (sys.version_info[0] == 3), 'Python 2 is no longer supported.'
 
 
-def py_str(x: CStrPtr) -> str:
+def py_str(x: bytes) -> str:
     """convert c string back to python string"""
     return x.decode('utf-8')  # type: ignore
 
@@ -103,16 +101,6 @@ class XGBoostLabelEncoder(LabelEncoder):
         self.__dict__.update(meta)
 
 
-# dask
-try:
-    import pkg_resources
-    pkg_resources.get_distribution('dask')
-    DASK_INSTALLED = True
-except pkg_resources.DistributionNotFound:
-    dask = None
-    DASK_INSTALLED = False
-
-
 try:
     import scipy.sparse as scipy_sparse
     from scipy.sparse import csr_matrix as scipy_csr

python-package/xgboost/config.py

@@ -114,7 +114,9 @@ def set_config(**new_config: Any) -> None:
 def get_config() -> Dict[str, Any]:
     config_str = ctypes.c_char_p()
     _check_call(_LIB.XGBGetGlobalConfig(ctypes.byref(config_str)))
-    config = json.loads(py_str(config_str.value))
+    value = config_str.value
+    assert value
+    config = json.loads(py_str(value))
     return config
 
 

python-package/xgboost/core.py

@@ -43,7 +43,7 @@ class XGBoostError(ValueError):
     """Error thrown by xgboost trainer."""
 
 
-def from_pystr_to_cstr(data: Union[str, List[str]]) -> Union[bytes, CStrPptr]:
+def from_pystr_to_cstr(data: Union[str, List[str]]) -> Union[bytes, ctypes.Array]:
     """Convert a Python str or list of Python str to C pointer
 
     Parameters
@@ -55,9 +55,9 @@ def from_pystr_to_cstr(data: Union[str, List[str]]) -> Union[bytes, CStrPptr]:
     if isinstance(data, str):
         return bytes(data, "utf-8")
     if isinstance(data, list):
-        pointers: ctypes.pointer = (ctypes.c_char_p * len(data))()
+        pointers: ctypes.Array[ctypes.c_char_p] = (ctypes.c_char_p * len(data))()
         data_as_bytes = [bytes(d, 'utf-8') for d in data]
-        pointers[:] = data_as_bytes
+        pointers[:] = data_as_bytes  # type: ignore
         return pointers
     raise TypeError()
 
@@ -272,7 +272,7 @@ def _cuda_array_interface(data: DataType) -> bytes:
 def ctypes2numpy(cptr: CNumericPtr, length: int, dtype: Type[np.number]) -> np.ndarray:
     """Convert a ctypes pointer array to a numpy array."""
     ctype: Type[CNumeric] = _numpy2ctypes_type(dtype)
-    if not isinstance(cptr, ctypes.POINTER(ctype)):
+    if not isinstance(cptr, ctypes.POINTER(ctype)):  # type: ignore
         raise RuntimeError(f"expected {ctype} pointer")
     res = np.zeros(length, dtype=dtype)
     if not ctypes.memmove(res.ctypes.data, cptr, length * res.strides[0]):  # type: ignore
@@ -287,7 +287,10 @@ def ctypes2cupy(cptr: CNumericPtr, length: int, dtype: Type[np.number]) -> CupyT
     from cupy.cuda.memory import MemoryPointer
     from cupy.cuda.memory import UnownedMemory
 
-    CUPY_TO_CTYPES_MAPPING = {cupy.float32: ctypes.c_float, cupy.uint32: ctypes.c_uint}
+    CUPY_TO_CTYPES_MAPPING: Dict[Type[np.number], Type[CNumeric]] = {
+        cupy.float32: ctypes.c_float,
+        cupy.uint32: ctypes.c_uint,
+    }
     if dtype not in CUPY_TO_CTYPES_MAPPING:
         raise RuntimeError(f"Supported types: {CUPY_TO_CTYPES_MAPPING.keys()}")
     addr = ctypes.cast(cptr, ctypes.c_void_p).value
@@ -322,10 +325,12 @@ def c_str(string: str) -> ctypes.c_char_p:
     return ctypes.c_char_p(string.encode('utf-8'))
 
 
-def c_array(ctype: Type[CTypeT], values: ArrayLike) -> ctypes.Array:
+def c_array(
+    ctype: Type[CTypeT], values: ArrayLike
+) -> Union[ctypes.Array, ctypes.pointer]:
     """Convert a python string to c array."""
     if isinstance(values, np.ndarray) and values.dtype.itemsize == ctypes.sizeof(ctype):
-        return (ctype * len(values)).from_buffer_copy(values)
+        return values.ctypes.data_as(ctypes.POINTER(ctype))
     return (ctype * len(values))(*values)
 
 
@@ -1611,7 +1616,9 @@ class Booster:
         _check_call(_LIB.XGBoosterGetAttr(
             self.handle, c_str(key), ctypes.byref(ret), ctypes.byref(success)))
         if success.value != 0:
-            return py_str(ret.value)
+            value = ret.value
+            assert value
+            return py_str(value)
         return None
 
     def attributes(self) -> Dict[str, Optional[str]]:
@@ -1639,12 +1646,10 @@ class Booster:
             The attributes to set. Setting a value to None deletes an attribute.
         """
         for key, value in kwargs.items():
+            c_value = None
             if value is not None:
-                if not isinstance(value, str):
-                    raise ValueError("Set Attr only accepts string values")
-                value = c_str(str(value))
-            _check_call(_LIB.XGBoosterSetAttr(
-                self.handle, c_str(key), value))
+                c_value = c_str(str(value))
+            _check_call(_LIB.XGBoosterSetAttr(self.handle, c_str(key), c_value))
 
     def _get_feature_info(self, field: str) -> Optional[FeatureInfo]:
         length = c_bst_ulong()
@@ -2628,10 +2633,10 @@ class Booster:
         bins = max(min(n_unique, bins) if bins is not None else n_unique, 1)
 
         nph = np.histogram(values, bins=bins)
-        nph = np.column_stack((nph[1][1:], nph[0]))
-        nph = nph[nph[:, 1] > 0]
+        nph_stacked = np.column_stack((nph[1][1:], nph[0]))
+        nph_stacked = nph_stacked[nph_stacked[:, 1] > 0]
 
-        if nph.size == 0:
+        if nph_stacked.size == 0:
             ft = self.feature_types
             fn = self.feature_names
             if fn is None:
@@ -2649,11 +2654,11 @@ class Booster:
                 )
 
         if as_pandas and PANDAS_INSTALLED:
-            return DataFrame(nph, columns=['SplitValue', 'Count'])
+            return DataFrame(nph_stacked, columns=['SplitValue', 'Count'])
         if as_pandas and not PANDAS_INSTALLED:
             warnings.warn(
                 "Returning histogram as ndarray"
                 " (as_pandas == True, but pandas is not installed).",
                 UserWarning
             )
-        return nph
+        return nph_stacked

tests/python/testing.py

@@ -7,7 +7,6 @@ from typing import Optional
 from contextlib import contextmanager
 from io import StringIO
 from xgboost.compat import SKLEARN_INSTALLED, PANDAS_INSTALLED
-from xgboost.compat import DASK_INSTALLED
 import pytest
 import gc
 import xgboost as xgb
@@ -44,8 +43,14 @@ def no_sklearn():
 
 
 def no_dask():
-    return {'condition': not DASK_INSTALLED,
-            'reason': 'Dask is not installed'}
+    try:
+        import pkg_resources
+
+        pkg_resources.get_distribution("dask")
+        DASK_INSTALLED = True
+    except pkg_resources.DistributionNotFound:
+        DASK_INSTALLED = False
+    return {"condition": not DASK_INSTALLED, "reason": "Dask is not installed"}
 
 
 def no_pandas():