NVIDIA Jetson Xavier NX入门（3）——pytorch和torchvision安装
NVIDIA下载pytorch官方网址是：https://forums.developer.nvidia.com/t/pytorch-for-jetson-version-1-9-0-now-available/72048
下载好后，在下载文件目录下输入指令：
pip3 install torch-1.8.0-cp36-cp36m-linux_aarch64.whl
安装完毕后可以在终端输入以下命令检验PyTorch是否正确安装：
python -c 'import torch; print(torch.cuda.is_available())'
正常来说，会返回True。
出现报错1：博主本人在安装后出现错误(NVIDIA Jetson Xavier NX安装pytorch时import torch时报OSError: libmpi_cxx.so.20: cannot open shared object file: No such file or directory)：
import torch
Traceback (most recent call last):
File “”, line 1, in
File “/home/*/.local/lib/python3.6/site-packages/torch/init.py”, line 188, in
_load_global_deps()
File “/home/*/.local/lib/python3.6/site-packages/torch/init.py”, line 141, in _load_global_deps
ctypes.CDLL(lib_path, mode=ctypes.RTLD_GLOBAL)
File “/usr/lib/python3.6/ctypes/init.py”, line 348, in init
self._handle = _dlopen(self._name, mode)
OSError: libmpi_cxx.so.20: cannot open shared object file: No such file or directory
有库没有安装，输入指令：
sudo apt-get install libopenblas-base libopenmpi-dev
出现报错2：Illegal instruction (core dumped)如果出现Illegal instruction (core dumped)的错误，这是由于numpy 1.19.5和OpenBLAS冲突引起的，修改其中一项即可。选择以下两种做法之一：
（1）降低numpy版本：
pip3 install -U numpy==1.19.4
（2）设置OpenBLAS
vim ~/.bashrc
加入：
export OPENBLAS_CORETYPE=ARMV8
激活.bashrc：
source ~/.bashrc
Pytorch除了torch包之外还需要安装对应的torchvision才能运行，两者的版本对应关系如下图：
输入指令：
sudo apt-get install libjpeg-dev zlib1g-dev libpython3-dev libavcodec-dev libavformat-dev libswscale-dev
git clone --branch <version> https://github.com/pytorch/vision torchvision # see below for version of torchvision to download
cd torchvision
export BUILD_VERSION=0.x.0 # where 0.x.0 is the torchvision version
python3 setup.py install --user
cd ../ # attempting to load torchvision from build dir will result in import error
pip install 'pillow<7' # always needed for Python 2.7, not needed torchvision v0.5.0+ with Python 3.6
到此NVIDIA Jetson Xavier NX环境的基本配置已经完成，当出现无法定位软件包（Unable to locate package）的情况，首先使用sudo apt-get update指令。