MAINT: Remove unused imports and unreachable code (numpy#18762)

* Remove unnecessary imports and minor fixes

Author: donno2048

numpy/compat/py3k.py

@@ -20,10 +20,6 @@
 import os
 from pathlib import Path
 import io
-
-import abc
-from abc import ABC as abc_ABC
-
 try:
     import pickle5 as pickle
 except ImportError:

numpy/core/multiarray.py

@@ -7,8 +7,6 @@
 """
 
 import functools
-import warnings
-
 from . import overrides
 from . import _multiarray_umath
 from ._multiarray_umath import *  # noqa: F403

numpy/lib/format.py

@@ -606,7 +606,7 @@ def _read_array_header(fp, version):
     if EXPECTED_KEYS != d.keys():
         keys = sorted(d.keys())
         msg = "Header does not contain the correct keys: {!r}"
-        raise ValueError(msg.format(d.keys()))
+        raise ValueError(msg.format(keys))
 
     # Sanity-check the values.
     if (not isinstance(d['shape'], tuple) or

numpy/lib/index_tricks.py

@@ -201,7 +201,6 @@ def __getitem__(self, key):
                 length = int(step)
                 if step != 1:
                     step = (key.stop-start)/float(step-1)
-                stop = key.stop + step
                 return _nx.arange(0, length, 1, float)*step + start
             else:
                 return _nx.arange(start, stop, step)

numpy/ma/extras.py

@@ -743,7 +743,6 @@ def _median(a, axis=None, out=None, overwrite_input=False):
         return np.ma.mean(asorted[indexer], axis=axis, out=out)
 
     if asorted.ndim == 1:
-        counts = count(asorted)
         idx, odd = divmod(count(asorted), 2)
         mid = asorted[idx + odd - 1:idx + 1]
         if np.issubdtype(asorted.dtype, np.inexact) and asorted.size > 0:

numpy/ma/mrecords.py

@@ -129,7 +129,6 @@ def __new__(cls, shape, dtype=None, buf=None, offset=0, strides=None,
                     msg = "Mask and data not compatible: data size is %i, " + \
                           "mask size is %i."
                     raise MAError(msg % (nd, nm))
-                copy = True
             if not keep_mask:
                 self.__setmask__(mask)
                 self._sharedmask = True

numpy/typing/_array_like.py

@@ -2,7 +2,6 @@
 
 import sys
 from typing import Any, Sequence, TYPE_CHECKING, Union, TypeVar, Generic
-
 from numpy import (
     ndarray,
     dtype,
@@ -20,9 +19,7 @@
     str_,
     bytes_,
 )
-
 from . import _HAS_TYPING_EXTENSIONS
-from ._dtype_like import DTypeLike
 
 if sys.version_info >= (3, 8):
     from typing import Protocol