树莓派安装 pytorch 遇到这个问题 ：pip install torch-1.7.0a0-cp37-cp37m-linux_armv7l.whl
ERROR: Exception:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/pip/_internal/cli/base_command.py", line 223, in _main
    status = self.run(options, args)
  File "/usr/lib/python3/dist-packages/pip/_internal/cli/req_command.py", line 180, in wrapper
    return func(self, options, args)
  File "/usr/lib/python3/dist-packages/pip/_internal/commands/install.py", line 306, in run
    wheel_cache = WheelCache(options.cache_dir, options.format_control)
  File "/usr/lib/python3/dist-packages/pip/_internal/cache.py", line 293, in __init__
    self._ephem_cache = EphemWheelCache(format_control)
  File "/usr/lib/python3/dist-packages/pip/_internal/cache.py", line 260, in __init__
    self._temp_dir = TempDirectory(
  File "/usr/lib/python3/dist-packages/pip/_internal/utils/temp_dir.py", line 141, in __init__
    path = self._create(kind)
  File "/usr/lib/python3/dist-packages/pip/_internal/utils/temp_dir.py", line 189, in _create
    tempfile.mkdtemp(prefix="pip-{}-".format(kind))
  File "/usr/lib/python3.9/tempfile.py", line 487, in mkdtemp
    prefix, suffix, dir, output_type = _sanitize_params(prefix, suffix, dir)
  File "/usr/lib/python3.9/tempfile.py", line 257, in _sanitize_params
    dir = gettempdir()
  File "/usr/lib/python3.9/tempfile.py", line 426, in gettempdir
    tempdir = _get_default_tempdir()
  File "/usr/lib/python3.9/tempfile.py", line 358, in _get_default_tempdir
    raise FileNotFoundError(_errno.ENOENT,
FileNotFoundError: [Errno 2] No usable temporary directory found in ['/tmp', '/var/tmp', '/usr/tmp', '/home/pi/ASR/torch1.7+torchvision-0.8']

应该是没权限导致的，所以后边又加了sudo pip install torch-1.7.0a0-cp37-cp37m-linux_armv7l.whl 

sudo pip install torch-1.7.0a0-cp37-cp37m-linux_armv7l.whl
Looking in indexes: https://pypi.org/simple, https://www.piwheels.org/simple
ERROR: torch-1.7.0a0-cp37-cp37m-linux_armv7l.whl is not a supported wheel on this platform.

又有了新问题：平台不支持

        >>> import pip._internal.pep425tags
>>> print(pip._internal.pep425tags.get_supported())
[('cp38', 'cp38', 'linux_armv7l'), ('cp38', 'abi3', 'linux_armv7l'), ('cp38', 'none', 'linux_armv7l'), ('cp37', 'abi3', 'linux_armv7l'), ('cp36', 'abi3', 'linux_armv7l'), ('cp35', 'abi3', 'linux_armv7l'), ('cp34', 'abi3', 'linux_armv7l'), ('cp33', 'abi3', 'linux_armv7l'), ('cp32', 'abi3', 'linux_armv7l'), ('py3', 'none', 'linux_armv7l'), ('cp38', 'none', 'any'), ('cp3', 'none', 'any'), ('py38', 'none', 'any'), ('py3', 'none', 'any'), ('py37', 'none', 'any'), ('py36', 'none', 'any'), ('py35', 'none', 'any'), ('py34', 'none', 'any'), ('py33', 'none', 'any'), ('py32', 'none', 'any'), ('py31', 'none', 'any'), ('py30', 'none', 'any')]
>>>
发现pip支持的版本中没有这个whl名字的后缀。更改whl的名字到 ('cp37', 'abi3', 'linux_armv7l')

\sudo pip install torch-1.6.0a0+b31f58d-cp37-abi3-linux_armv7l.whl
Looking in indexes: https://pypi.org/simple, https://www.piwheels.org/simple
Processing ./torch-1.6.0a0+b31f58d-cp37-abi3-linux_armv7l.whl
Collecting future
  Downloading https://www.piwheels.org/simple/future/future-0.18.2-py3-none-any.whl (491 kB)
     |████████████████████████████████| 491 kB 144 kB/s
Requirement already satisfied: numpy in /usr/local/lib/python3.9/dist-packages (from torch==1.6.0a0+b31f58d) (1.22.1)
Installing collected packages: future, torch
Successfully installed future-0.18.2 torch-1.6.0a0+b31f58d 发现 安装成功。