Summary of operation methods in the os.path path module in Python-Python Tutorial-php.cn

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Summary of operation methods in the os.path path module in Python

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Jul 22, 2016 am 08:56 AM

python folder Table of contents

解析路径
路径解析依赖与os中定义的一些变量：

os.sep-路径各部分之间的分隔符。
os.extsep-文件名与文件扩展名之间的分隔符。
os.pardir-路径中表示目录树上一级的部分。
os.curdir-路径中当前目录的部分。

split()函数将路径分解为两个单独的部分，并返回包含这些结果的tuple。第二个元素是路径的最后部分，地一个元素是其他部分。

import os.path
for path in [ '/one/two/three',
        '/one/two/three/',
        '/',
        '.',
        '']:
  print '%15s : %s' % (path, os.path.split(path))

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输入参数以os.sep结尾时，最后一个元素是空串。

输出：

 /one/two/three : ('/one/two', 'three')
/one/two/three/ : ('/one/two/three', '')
       / : ('/', '')
       . : ('', '.')
        : ('', '')

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basename()函数返回的值等价与split()值的第二部分。

import os.path
for path in [ '/one/two/three',
        '/one/two/three/',
        '/',
        '.',
        '']:
  print '%15s : %s' % (path, os.path.basename(path))

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整个路径会剥除到只剩下最后一个元素。

输出：

 /one/two/three : three
/one/two/three/ : 
       / : 
       . : .
        :

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dirname()函数返回分解路径得到的第一部分。

import os.path
for path in [ '/one/two/three',
        '/one/two/three/',
        '/',
        '.',
        '']:
  print '%15s : %s' % (path, os.path.dirname(path))

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将basename()与dirname()结合，得到原来的路径。

 /one/two/three : /one/two
/one/two/three/ : /one/two/three
       / : /
       . : 
        :

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splitext()作用类似与split(),不过它会根据扩展名分隔符而不是目录分隔符来分解路径。import os.path

for path in [ '/one.txt',
        '/one/two/three.txt',
        '/',
        '.',
        ''
        'two.tar.gz']:

  print '%21s : %s' % (path, os.path.splitext(path))

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查找扩展名时，只使用os.extsep的最后一次出现。

       /one.txt : ('/one', '.txt')
  /one/two/three.txt : ('/one/two/three', '.txt')
          / : ('/', '')
          . : ('.', '')
      two.tar.gz : ('two.tar', '.gz')

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commonprefix()取一个路径列表作为参数，返回一个字符串，表示所有路径中出现的公共前缀。

import os.path
paths = [ '/one/two/three',
      '/one/two/threetxt',
      '/one/two/three/four',]
for path in paths:
  print 'PATH:', path

print
print 'PREFIX:', os.path.commonprefix(paths)

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输出：

PATH: /one/two/three
PATH: /one/two/threetxt
PATH: /one/two/three/four

PREFIX: /one/two/three

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建立路径
除了分解现有路径外，还需要从其他字符串建立路径，使用join()。

import os.path
for parts in [ ('one', 'two', 'three'),
      ('\one', 'two', 'three'),
      ('/one', '/two', '/three', '/four'),]:

  print parts, ':', os.path.join(*parts)

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如果要连接的某个参数以os.sep开头，前面所有参数都会丢弃，参数会返回值的开始部分。

('one', 'two', 'three') : one\two\three
('\\one', 'two', 'three') : \one\two\three
('/one', '/two', '/three', '/four') : /four

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规范化路径
使用join()或利用嵌入变量由单独的字符串组合路径时，得到的路径最后可能会有多余的分隔符或者相对路径部分，使用normpath()可以清除这些内容。

import os.path
for path in [ 'one/two/three',
       'one/./two/three',
       'one/../alt/two/three',
       ]:
  print '%20s : %s' % (path, os.path.normpath(path))

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可以计算并压缩有os.curdir和os.pardir构成的路径段。

    one/two/three : one\two\three
   one/./two/three : one\two\three
one/../alt/two/three : alt\two\three

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要把一个相对路径转换为一个绝对文件名，可以使用abspath()。

import os.path
for path in [ '.',
       '..',
       'one/two/three',
       'one/./two/three',
       'one/../alt/two/three',
       ]:
  print '%20s : %s' % (path, os.path.abspath(path))

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结果是从一个文件系统树最顶层开始的完整路径。

          . : C:\Users\Administrator\Desktop
         .. : C:\Users\Administrator
    one/two/three : C:\Users\Administrator\Desktop\one\two\three
   one/./two/three : C:\Users\Administrator\Desktop\one\two\three
one/../alt/two/three : C:\Users\Administrator\Desktop\alt\two\three

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文件时间

import os
import time
print 'File:', __file__
print 'Access time:', time.ctime(os.path.getatime(__file__))
print 'Modified time:', time.ctime(os.path.getmtime(__file__))
print 'Change time:', time.ctime(os.path.getctime(__time__))
print 'Size:', os.path.getsize(__file__)

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返回访问时间，修改时间，创建时间，文件中的数据量。

测试文件
程序遇到一个路径名，通常需要知道这个路径的一些信息。

import os.path
filename = r'C:\Users\Administrator\Desktop\tmp'
print 'File    :', filename
print 'Is file&#63;   :', os.path.isfile(filename)
print 'Absoulute  :', os.path.isabs(filename)
print 'Is dir&#63;   :', os.path.isdir(filename)
print 'Is link&#63;   :', os.path.islink(filename)
print 'Mountpoint&#63; :', os.path.ismount(filename)
print 'Exists&#63;    :', os.path.exists(filename)
print 'Link Exists&#63; :', os.path.lexists(filename)

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所有测试都返回布尔值。

File    : C:\Users\Administrator\Desktop\tmp
Is file&#63;   : False
Absoulute  : True
Is dir&#63;   : True
Is link&#63;   : False
Mountpoint&#63; : False
Exists&#63;    : True
Link Exists&#63; : True

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遍历一个目录树

import os
import os.path
import pprint
def visit(arg, dirname, names):
  print dirname, arg
  for name in names:
    subname = os.path.join(dirname, name)
    if os.path.isdir(subname):
      print '%s/' % name 
    else:
      print ' %s' % name
  print
if not os.path.exists('example'):
  os.mkdir('example')
if not os.path.exists('example/one'):
  os.mkdir('example/one')
with open('example/one/file.txt', 'wt') as f:
  f.write('i love you')
with open('example/one/another.txt', 'wt') as f:
  f.write('i love you, two')
os.path.walk('example', visit, '(User data)')

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会生成一个递归的目录列表。

example (User data)
one/

example\one (User data)
 another.txt
 file.txt

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一些实际的用法合集：

#创建文件：
os.mknod("test.txt")    创建空文件
fp = open("test.txt",w)   直接打开一个文件，如果文件不存在则创建文件
 
#获取扩展名：
>>> os.path.splitext('/Volumes/Leopard/Users/Caroline/Desktop/1.mp4')[1:]
('.mp4',)
>>> os.path.splitext('/Volumes/Leopard/Users/Caroline/Desktop/1.mp4')[1]
'.mp4'
 
#获取文件名：
>>> print os.path.basename(r'/root/hahaha/123.txt')
123.txt
>>> print os.path.dirname(r'/root/hahaha/123.txt')
/root/hahaha
 
#判断目录或文件的存在：
>>> os.path.exists('/root/1.py')
True
>>> os.path.exists('/root/')
True
>>> os.path.exists('/root')
True
>>> os.path.isdir('/root')
True
 
#改变工作目录：
>>> os.chdir('/home')
>>> os.getcwd()
'/home'
 
#字符串分割：
>>> '/usr/bin/env'.split('/')
['', 'usr', 'bin', 'env']
 
#获取文件夹大小（Python2.x）：
import os 
from os.path import join, getsize 
  
def getdirsize(dir): 
  size = 0L 
  for root, dirs, files in os.walk(dir): 
   size += sum([getsize(join(root, name)) for name in files]) 
  return size 
  
if __name__ == '__main__':
  filesize = getdirsize('/tmp') 
  print 'There are %.3f' % (filesize/1024/1024), 'Mbytes in /tmp' 
 
#获取文件夹大小（Python3.x）：
import os 
from os.path import join, getsize 
  
def getdirsize(dir): 
  size = 0 
  for root, dirs, files in os.walk(dir): 
   size += sum([getsize(join(root, name)) for name in files]) 
  return size 
  
if __name__ == '__main__':
  filesize = getdirsize('/tmp') 
  print ('There are ' + str(filesize/1024/1024) + 'Mbytes in /tmp')

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