Windows10下PyTorch 怎么也没法import成功，重装了多次cuda驱动，各种版本也不行，更改这个脚本就成功了

我尝试了cuda9.2/10.1/10.2，但是最后无一例外都是提示DLL错误，无法import,最终翻阅外网的一个github，终于找到了解决方案，特记录一下：
方法是替换pytorch 的__init__.py文件，该文件的地址为：

https://gist.github.com/peterjc123/bcbf4418ff63d88e11313d308cf1b427

找到自己的环境下面的torch文件夹，然后用下面的内容替换其__init__.py。
为了防止内容失效，贴文件内容如下：

r"""
The torch package contains data structures for multi-dimensional
tensors and mathematical operations over these are defined.
Additionally, it provides many utilities for efficient serializing of
Tensors and arbitrary types, and other useful utilities.
It has a CUDA counterpart, that enables you to run your tensor computations
on an NVIDIA GPU with compute capability >= 3.0.
"""

import os
import sys
import platform
import ctypes

if sys.version_info < (3,):
    raise Exception("Python 2 has reached end-of-life and is no longer supported by PyTorch.")

from ._utils import _import_dotted_name
from ._utils_internal import get_file_path, prepare_multiprocessing_environment, \
    USE_RTLD_GLOBAL_WITH_LIBTORCH
from .version import __version__
from ._six import string_classes as _string_classes

__all__ = [
    'typename', 'is_tensor', 'is_storage', 'set_default_tensor_type',
    'set_rng_state', 'get_rng_state', 'manual_seed', 'initial_seed', 'seed',
    'save', 'load', 'set_printoptions', 'chunk', 'split', 'stack', 'matmul',
    'no_grad', 'enable_grad', 'rand', 'randn',
    'DoubleStorage', 'FloatStorage', 'LongStorage', 'IntStorage',
    'ShortStorage', 'CharStorage', 'ByteStorage', 'BoolStorage',
    'DoubleTensor', 'FloatTensor', 'LongTensor', 'IntTensor',
    'ShortTensor', 'CharTensor', 'ByteTensor', 'BoolTensor', 'Tensor',
    'lobpcg',
]

################################################################################
# Load the extension module
################################################################################

if platform.system() == 'Windows':
    is_conda = os.path.exists(os.path.join(sys.prefix, 'conda-meta'))
    py_dll_path = os.path.join(sys.exec_prefix, 'Library', 'bin')
    th_dll_path = os.path.join(os.path.dirname(__file__), 'lib')

    if not os.path.exists(os.path.join(th_dll_path, 'nvToolsExt64_1.dll')) and \
            not os.path.exists(os.path.join(py_dll_path, 'nvToolsExt64_1.dll')):
        nvtoolsext_dll_path = os.path.join(
            os.getenv('NVTOOLSEXT_PATH', 'C:\\Program Files\\NVIDIA Corporation\\NvToolsExt'), 'bin', 'x64')
    else:
        nvtoolsext_dll_path = ''

    from .version import cuda as cuda_version
    import glob
    if cuda_version and len(glob.glob(os.path.join(th_dll_path, 'cudart64*.dll'))) == 0 and \
            len(glob.glob(os.path.join(py_dll_path, 'cudart64*.dll'))) == 0:
        cuda_version_1 = cuda_version.replace('.', '_')
        cuda_path_var = 'CUDA_PATH_V' + cuda_version_1
        default_path = 'C:\\Program Files\\NVIDIA GPU Computing Toolkit\\CUDA\\v' + cuda_version
        cuda_path = os.path.join(os.getenv(cuda_path_var, default_path), 'bin')
    else:
        cuda_path = ''

    kernel32 = ctypes.WinDLL('kernel32.dll', use_last_error=True)
    dll_paths = list(filter(os.path.exists, [th_dll_path, py_dll_path, nvtoolsext_dll_path, cuda_path]))
    with_load_library_flags = hasattr(kernel32, 'AddDllDirectory')
    prev_error_mode = kernel32.SetErrorMode(0x0001)

    for dll_path in dll_paths:
        if sys.version_info >= (3, 8):
            os.add_dll_directory(dll_path)
        elif with_load_library_flags:
            res = kernel32.AddDllDirectory(dll_path)
            if res == 0:
                err = ctypes.WinError(ctypes.get_last_error())
                err.strerror += ' Error adding "{}" to the DLL directories.'.format(dll_path)
                raise err

    import glob
    dlls = glob.glob(os.path.join(th_dll_path, '*.dll'))
    path_patched = False
    for dll in dlls:
        is_loaded = False
        if with_load_library_flags:
            res = kernel32.LoadLibraryExW(dll, 0, 0x00001100)
            last_error = ctypes.get_last_error()
            if res == 0 and last_error != 126:
                err = ctypes.WinError(last_error)
                err.strerror += ' Error loading "{}" or one of its dependencies.'.format(dll)
                raise err
            elif res != 0:
                is_loaded = True
        if not is_loaded:
            if not path_patched:
                os.environ['PATH'] = ';'.join(dll_paths + [os.environ['PATH']])
                path_patched = True
            res = kernel32.LoadLibraryW(dll)
            if res == 0:
                err = ctypes.WinError(ctypes.get_last_error())
                err.strerror += ' Error loading "{}" or one of its dependencies.'.format(dll)
                raise err

    kernel32.SetErrorMode(prev_error_mode)


# See Note [Global dependencies]
def _load_global_deps():
    if platform.system() == 'Windows':
        return

    lib_name = 'libtorch_global_deps' + ('.dylib' if platform.system() == 'Darwin' else '.so')
    here = os.path.abspath(__file__)
    lib_path = os.path.join(os.path.dirname(here), 'lib', lib_name)

    ctypes.CDLL(lib_path, mode=ctypes.RTLD_GLOBAL)


if (USE_RTLD_GLOBAL_WITH_LIBTORCH or os.getenv('TORCH_USE_RTLD_GLOBAL')) and \
        platform.system() != 'Windows':
    # Do it the hard way.  You might want to load libtorch with RTLD_GLOBAL in a
    # few circumstances:
    #
    #   1. You're in a build environment (e.g., fbcode) where
    #      libtorch_global_deps is not available, but you still need
    #      to get mkl to link in with RTLD_GLOBAL or it will just
    #      not work.
    #
    #   2. You're trying to run PyTorch under UBSAN and you need
    #      to ensure that only one copy of libtorch is loaded, so
    #      vptr checks work properly
    #
    # If you're using this setting, you must verify that all the libraries
    # you load consistently use the same libstdc++, or you may have
    # mysterious segfaults.
    #
    import os as _dl_flags
    if not hasattr(_dl_flags, 'RTLD_GLOBAL') or not hasattr(_dl_flags, 'RTLD_LAZY'):
        try:
            # next try if DLFCN exists
            import DLFCN as _dl_flags
        except ImportError:
            # as a last attempt, use compile-time constants
            import torch._dl as _dl_flags
    old_flags = sys.getdlopenflags()
    sys.setdlopenflags(_dl_flags.RTLD_GLOBAL | _dl_flags.RTLD_LAZY)
    from torch._C import *
    sys.setdlopenflags(old_flags)
    del old_flags
    del _dl_flags

else:
    # Easy way.  You want this most of the time, because it will prevent
    # C++ symbols from libtorch clobbering C++ symbols from other
    # libraries, leading to mysterious segfaults.
    #
    # See Note [Global dependencies]
    _load_global_deps()
    from torch._C import *

__all__ += [name for name in dir(_C)
            if name[0] != '_' and
            not name.endswith('Base')]

################################################################################
# Define basic utilities
################################################################################


def typename(o):
    if isinstance(o, torch.Tensor):
        return o.type()

    module = ''
    class_name = ''
    if hasattr(o, '__module__') and o.__module__ != 'builtins' \
            and o.__module__ != '__builtin__' and o.__module__ is not None:
        module = o.__module__ + '.'

    if hasattr(o, '__qualname__'):
        class_name = o.__qualname__
    elif hasattr(o, '__name__'):
        class_name = o.__name__
    else:
        class_name = o.__class__.__name__

    return module + class_name


def is_tensor(obj):
    r"""Returns True if `obj` is a PyTorch tensor.
    Args:
        obj (Object): Object to test
    """
    return isinstance(obj, torch.Tensor)


def is_storage(obj):
    r"""Returns True if `obj` is a PyTorch storage object.
    Args:
        obj (Object): Object to test
    """
    return type(obj) in _storage_classes


def set_default_tensor_type(t):
    r"""Sets the default ``torch.Tensor`` type to floating point tensor type
    ``t``. This type will also be used as default floating point type for
    type inference in :func:`torch.tensor`.
    The default floating point tensor type is initially ``torch.FloatTensor``.
    Args:
        t (type or string): the floating point tensor type or its name
    Example::
        >>> torch.tensor([1.2, 3]).dtype    # initial default for floating point is torch.float32
        torch.float32
        >>> torch.set_default_tensor_type(torch.DoubleTensor)
        >>> torch.tensor([1.2, 3]).dtype    # a new floating point tensor
        torch.float64
    """
    if isinstance(t, _string_classes):
        t = _import_dotted_name(t)
    _C._set_default_tensor_type(t)


def set_default_dtype(d):
    r"""Sets the default floating point dtype to :attr:`d`. This type will be
    used as default floating point type for type inference in
    :func:`torch.tensor`.
    The default floating point dtype is initially ``torch.float32``.
    Args:
        d (:class:`torch.dtype`): the floating point dtype to make the default
    Example::
        >>> torch.tensor([1.2, 3]).dtype           # initial default for floating point is torch.float32
        torch.float32
        >>> torch.set_default_dtype(torch.float64)
        >>> torch.tensor([1.2, 3]).dtype           # a new floating point tensor
        torch.float64
    """
    _C._set_default_dtype(d)

# If you edit these imports, please update torch/__init__.py.in as well
from .random import set_rng_state, get_rng_state, manual_seed, initial_seed, seed
from .serialization import save, load
from ._tensor_str import set_printoptions

################################################################################
# Define Storage and Tensor classes
################################################################################

from .tensor import Tensor
from .storage import _StorageBase


class DoubleStorage(_C.DoubleStorageBase, _StorageBase):
    pass


class FloatStorage(_C.FloatStorageBase, _StorageBase):
    pass


class HalfStorage(_C.HalfStorageBase, _StorageBase):
    pass


class LongStorage(_C.LongStorageBase, _StorageBase):
    pass


class IntStorage(_C.IntStorageBase, _StorageBase):
    pass


class ShortStorage(_C.ShortStorageBase, _StorageBase):
    pass


class CharStorage(_C.CharStorageBase, _StorageBase):
    pass


class ByteStorage(_C.ByteStorageBase, _StorageBase):
    pass


class BoolStorage(_C.BoolStorageBase, _StorageBase):
    pass


class BFloat16Storage(_C.BFloat16StorageBase, _StorageBase):
    pass


class QUInt8Storage(_C.QUInt8StorageBase, _StorageBase):
    pass

class QInt8Storage(_C.QInt8StorageBase, _StorageBase):
    pass

class QInt32Storage(_C.QInt32StorageBase, _StorageBase):
    pass


_storage_classes = {
    DoubleStorage, FloatStorage, LongStorage, IntStorage, ShortStorage,
    CharStorage, ByteStorage, HalfStorage, BoolStorage, QUInt8Storage, QInt8Storage,
    QInt32Storage, BFloat16Storage
}

# The _tensor_classes set is initialized by the call to _C._initialize_tensor_type_bindings()
_tensor_classes = set()


################################################################################
# Initialize extension
################################################################################

def manager_path():
    if platform.system() == 'Windows':
        return b""
    path = get_file_path('torch', 'bin', 'torch_shm_manager')
    prepare_multiprocessing_environment(get_file_path('torch'))
    if not os.path.exists(path):
        raise RuntimeError("Unable to find torch_shm_manager at " + path)
    return path.encode('utf-8')


# Shared memory manager needs to know the exact location of manager executable
_C._initExtension(manager_path())
del manager_path

for name in dir(_C._VariableFunctions):
    if name.startswith('__'):
        continue
    globals()[name] = getattr(_C._VariableFunctions, name)

################################################################################
# Import interface functions defined in Python
################################################################################

# needs to be after the above ATen bindings so we can overwrite from Python side
from .functional import *


################################################################################
# Remove unnecessary members
################################################################################

del DoubleStorageBase
del FloatStorageBase
del LongStorageBase
del IntStorageBase
del ShortStorageBase
del CharStorageBase
del ByteStorageBase
del BoolStorageBase
del QUInt8StorageBase
del BFloat16StorageBase

################################################################################
# Import most common subpackages
################################################################################

import torch.cuda
import torch.autograd
from torch.autograd import no_grad, enable_grad, set_grad_enabled
import torch.nn
import torch.nn.intrinsic
import torch.nn.quantized
import torch.optim
import torch.multiprocessing
import torch.sparse
import torch.utils.backcompat
import torch.onnx
import torch.jit
import torch.hub
import torch.random
import torch.distributions
import torch.testing
import torch.backends.cuda
import torch.backends.mkl
import torch.backends.mkldnn
import torch.backends.openmp
import torch.backends.quantized
import torch.quantization
import torch.utils.data
import torch.__config__
import torch.__future__

_C._init_names(list(torch._storage_classes))

# attach docstrings to torch and tensor functions
from . import _torch_docs, _tensor_docs, _storage_docs
del _torch_docs, _tensor_docs, _storage_docs


def compiled_with_cxx11_abi():
    r"""Returns whether PyTorch was built with _GLIBCXX_USE_CXX11_ABI=1"""
    return _C._GLIBCXX_USE_CXX11_ABI


# Import the ops "namespace"
from torch._ops import ops
from torch._classes import classes

# Import the quasi random sampler
import torch.quasirandom

# If you are seeing this, it means that this call site was not checked if
# the memory format could be preserved, and it was switched to old default
# behaviour of contiguous
legacy_contiguous_format = contiguous_format

# Register fork handler to initialize OpenMP in child processes (see gh-28389)
from torch.multiprocessing._atfork import register_after_fork
register_after_fork(torch.get_num_threads)
del register_after_fork

# Import tools that require fully imported torch (for applying
# torch.jit.script as a decorator, for instance):
from ._lobpcg import lobpcg