Remove STRING_TYPES. (#7827)

python-package/xgboost/callback.py

@@ -16,7 +16,6 @@
 
 from . import rabit
 from .core import Booster, DMatrix, XGBoostError, _get_booster_layer_trees
-from .compat import STRING_TYPES
 
 
 __all__ = [
@@ -82,7 +81,7 @@ def _aggcv(rlist: List[str]) -> List[Tuple[str, float, float]]:
     results = []
     for (_, name), s in sorted(cvmap.items(), key=lambda x: x[0][0]):
         as_arr = numpy.array(s)
-        if not isinstance(msg, STRING_TYPES):
+        if not isinstance(msg, str):
             msg = msg.decode()
         mean, std = numpy.mean(as_arr), numpy.std(as_arr)
         results.extend([(name, mean, std)])

python-package/xgboost/compat.py

@@ -10,9 +10,6 @@
 
 assert (sys.version_info[0] == 3), 'Python 2 is no longer supported.'
 
-# pylint: disable=invalid-name, redefined-builtin
-STRING_TYPES = (str,)
-
 
 def py_str(x):
     """convert c string back to python string"""

python-package/xgboost/core.py

@@ -17,7 +17,7 @@
 import numpy as np
 import scipy.sparse
 
-from .compat import STRING_TYPES, DataFrame, py_str, PANDAS_INSTALLED
+from .compat import DataFrame, py_str, PANDAS_INSTALLED
 from .libpath import find_lib_path
 from ._typing import (
     CStrPptr,
@@ -1387,7 +1387,7 @@ def __init__(
             _check_call(
                 _LIB.XGBoosterUnserializeFromBuffer(self.handle, ptr, length))
             self.__dict__.update(state)
-        elif isinstance(model_file, (STRING_TYPES, os.PathLike, bytearray)):
+        elif isinstance(model_file, (str, os.PathLike, bytearray)):
             self.load_model(model_file)
         elif model_file is None:
             pass
@@ -1629,7 +1629,7 @@ def set_attr(self, **kwargs: Optional[str]) -> None:
         """
         for key, value in kwargs.items():
             if value is not None:
-                if not isinstance(value, STRING_TYPES):
+                if not isinstance(value, str):
                     raise ValueError("Set Attr only accepts string values")
                 value = c_str(str(value))
             _check_call(_LIB.XGBoosterSetAttr(
@@ -1705,7 +1705,7 @@ def set_param(
         """
         if isinstance(params, Mapping):
             params = params.items()
-        elif isinstance(params, STRING_TYPES) and value is not None:
+        elif isinstance(params, str) and value is not None:
             params = [(params, value)]
         for key, val in params:
             if val is not None:
@@ -1796,7 +1796,7 @@ def eval_set(
         for d in evals:
             if not isinstance(d[0], DMatrix):
                 raise TypeError(f"expected DMatrix, got {type(d[0]).__name__}")
-            if not isinstance(d[1], STRING_TYPES):
+            if not isinstance(d[1], str):
                 raise TypeError(f"expected string, got {type(d[1]).__name__}")
             self._validate_features(d[0])
 
@@ -2192,7 +2192,7 @@ def save_model(self, fname: Union[str, os.PathLike]) -> None:
             Output file name
 
         """
-        if isinstance(fname, (STRING_TYPES, os.PathLike)):  # assume file name
+        if isinstance(fname, (str, os.PathLike)):  # assume file name
             fname = os.fspath(os.path.expanduser(fname))
             _check_call(_LIB.XGBoosterSaveModel(
                 self.handle, c_str(fname)))
@@ -2301,7 +2301,7 @@ def dump_model(self, fout: Union[str, os.PathLike], fmap: Union[str, os.PathLike
         dump_format : string, optional
             Format of model dump file. Can be 'text' or 'json'.
         """
-        if isinstance(fout, (STRING_TYPES, os.PathLike)):
+        if isinstance(fout, (str, os.PathLike)):
             fout = os.fspath(os.path.expanduser(fout))
             # pylint: disable=consider-using-with
             fout_obj = open(fout, 'w', encoding="utf-8")

python-package/xgboost/rabit.py

@@ -6,7 +6,7 @@
 
 import numpy as np
 
-from .core import _LIB, c_str, STRING_TYPES, _check_call
+from .core import _LIB, c_str, _check_call
 
 
 def _init_rabit() -> None:
@@ -73,7 +73,7 @@ def tracker_print(msg: Any) -> None:
     msg : str
         The message to be printed to tracker.
     """
-    if not isinstance(msg, STRING_TYPES):
+    if not isinstance(msg, str):
         msg = str(msg)
     is_dist = _LIB.RabitIsDistributed()
     if is_dist != 0: