Pipenv问题：升级至Pandas 2.0后Staircase包被降级

环境与前置背景 #

• 工具版本：pipenv 2023.3.20、pip 21.1.3
• pandas升级异常：从1.5.3升级至2.0时，必须显式指定版本号，否则Pipfile.lock不会更新旧版本记录，这可能是后续问题的诱因

当前问题 #

staircase被降级到2.0.0后引发代码执行报错，尝试执行pipenv update staircase==2.5.0时触发依赖解析失败：

Warning: Your dependencies could not be resolved. You likely have a mismatch in your sub-dependencies.
You can use $ pipenv install --skip-lock to bypass this mechanism, then run $ pipenv graph to inspect the situation.
Hint: try $ pipenv lock --pre if it is a pre-release dependency.
ERROR: ResolutionImpossible

执行pipenv graph得到的staircase依赖链如下：

staircase==2.0.0
  - matplotlib [required: >=2, installed: 3.7.1]
    - contourpy [required: >=1.0.1, installed: 1.0.7]
      - numpy [required: >=1.16, installed: 1.23.5]
    - cycler [required: >=0.10, installed: 0.11.0]
    - fonttools [required: >=4.22.0, installed: 4.39.3]
    - importlib-resources [required: >=3.2.0, installed: 5.12.0]
      - zipp [required: >=3.1.0, installed: 3.15.0]
    - kiwisolver [required: >=1.0.1, installed: 1.4.4]
    - numpy [required: >=1.20, installed: 1.23.5]
    - packaging [required: >=20.0, installed: 23.0]
    - pillow [required: >=6.2.0, installed: 9.5.0]
    - pyparsing [required: >=2.3.1, installed: 3.0.9]
    - python-dateutil [required: >=2.7, installed: 2.8.2]
      - six [required: >=1.5, installed: 1.16.0]

解决步骤 #

1. 排查版本兼容性：优先确认staircase 2.5.0对pandas的版本要求——刚升级pandas到2.0，很大概率是staircase 2.5.0不兼容pandas 2.0，导致依赖解析失败。可查看staircase官方版本说明确认。
2. 强制联合安装指定版本：执行pipenv install pandas==2.0 staircase==2.5.0，让pipenv同时解析两个包的依赖约束，尝试生成兼容的锁文件。
3. 定位具体冲突点：如果上述命令失败，执行pipenv install --skip-lock跳过锁文件生成，再通过pipenv graph对比pandas 2.0和staircase 2.5.0的子依赖要求，找出具体冲突的包版本。
4. 升级pip增强解析能力：当前使用的pip 21.1.3版本较旧，新版本pip的依赖解析逻辑更完善。先执行pip install --upgrade pip升级pip，再重新运行pipenv lock尝试生成锁文件。

内容的提问来源于stack exchange，提问作者matsuo_basho