python操作上级子文件

.
└── folder
    ├── data
    │   └── data.txt
    └── test1
        └── test2
          └── test.py

import os

'***获取当前目录***'
print os.getcwd()
print os.path.abspath(os.path.dirname(__file__))

***获取上级目录***'
print os.path.abspath(os.path.dirname(os.path.dirname(__file__)))
print os.path.abspath(os.path.dirname(os.getcwd()))
print os.path.abspath(os.path.join(os.getcwd(), ".."))

'***获取上上级目录***'
print os.path.abspath(os.path.join(os.getcwd(), "../.."))
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windows系统，实例：

#假设当前在test.py，找到data.txt路径

parent_path = os.path.abspath(os.path.join(os.getcwd(), "../.."))

data_dir = os.path.join(parent_path, 'data\\data.txt')