Defaulting to user installation because normal site-packages is not writeable
Looking in indexes: http://pypi.tuna.tsinghua.edu.cn/simple
WARNING: The repository located at pypi.tuna.tsinghua.edu.cn is not a trusted or secure host and is being ignored. If this repository is available via HTTPS we recommend you use HTTPS instead, otherwise you may silence this warning and allow it anyway with '--trusted-host pypi.tuna.tsinghua.edu.cn'.
ERROR: Could not find a version that satisfies the requirement pandas (from versions: none)
ERROR: No matching distribution found for pandas
WARNING: The repository located at pypi.tuna.tsinghua.edu.cn is not a trusted or secure host and is being ignored. If this repository is available via HTTPS we recommend you use HTTPS instead, otherwise you may silence this warning and allow it anyway with '--trusted-host pypi.tuna.tsinghua.edu.cn'.pip install pandas -i http://pypi.douban.com/simple –trusted-host pypi.douban.com
上面已经经过验证
下面未经过验证：
出错情况：
pip install XXX pip3 install XXX
改成：
python -m pip install XXX python3 -m pip install XXX