sys.path用法介绍

介绍

sys.path指定模块搜索路径的列表。默认情况下，python导入文件或者模块，会在sys.path里找模块的路径。如果在当前搜索路径列表sys.path中找不到该模块的话，就会报错。

用法

最常用的用法就是向sys.path中添加搜索路径

import sys
sys.path.append(path)  # path 代表的是一个路径

举例

• 查看当前搜索路径

  import sys
  print(sys.path)
  

  ['/home/nsy/nlp/exp3', 
  '/home/nsy/anaconda3/envs/nlp/lib/python36.zip', 
  '/home/nsy/anaconda3/envs/nlp/lib/python3.6', 
  '/home/nsy/anaconda3/envs/nlp/lib/python3.6/lib-dynload',
  '/home/nsy/anaconda3/envs/nlp/lib/python3.6/site-packages',
  '/home/nsy/anaconda3/envs/nlp/lib/python3.6/site-packages/keras_contrib-2.0.8-py3.6.egg',
  '/home/nsy/anaconda3/envs/nlp/lib/python3.6/site-packages/dl_segmenter-0.1_SNAPSHOT-py3.6.egg']
  

  • 也就是说，如果我要导入python模块，那么会在这些路径下寻找

• 添加新的路径

  • 我现在有一个模块new_package，路径为/home/nsy/nlp/new_package，我直接import new_package是会报错的，因为在上面那些路径中找不到

    import sys
    import new_package
    
    >>Traceback (most recent call last):
      File "sys_test.py", line 2, in <module>
        import new_package
    ModuleNotFoundError: No module named 'new_package'
    

  • 添加路径，成功运行

    import sys
    sys.path.append('/home/nsy/nlp')
    import new_package
    print(sys.path)
    

    ['/home/nsy/nlp/exp3',
     '/home/nsy/anaconda3/envs/nlp/lib/python36.zip',
     '/home/nsy/anaconda3/envs/nlp/lib/python3.6',
     '/home/nsy/anaconda3/envs/nlp/lib/python3.6/lib-dynload',
     '/home/nsy/anaconda3/envs/nlp/lib/python3.6/site-packages',
     '/home/nsy/anaconda3/envs/nlp/lib/python3.6/site-packages/keras_contrib-2.0.8-py3.6.egg',
     '/home/nsy/anaconda3/envs/nlp/lib/python3.6/site-packages/dl_segmenter-0.1_SNAPSHOT-py3.6.egg',
     '/home/nsy/nlp']