Python中fileinput模块介绍

fileinput模块可以对一个或多个文件中的内容进行迭代、遍历等操作。

该模块的input()函数有点类似文件readlines()方法，区别在于:

前者是一个迭代对象，即每次只生成一行，需要用for循环迭代。

后者是一次性读取所有行。在碰到大文件的读取时，前者无疑效率更高效。

用fileinput对文件进行循环遍历，格式化输出，查找、替换等操作，非常方便。

【典型用法】

import fileinput
for line in fileinput.input():
    process(line)

【基本格式】

fileinput.input([files[, inplace[, backup[, bufsize[, mode[, openhook]]]]]])

【默认格式】

fileinput.input (files=None, inplace=False, backup='', bufsize=0, mode='r', openhook=None)

files: #文件的路径列表，默认是stdin方式，多文件['1.txt','2.txt',...]

inplace: #是否将标准输出的结果写回文件，默认不取代

backup: #备份文件的扩展名，只指定扩展名，如.bak。如果该文件的备份文件已存在，则会自动覆盖。

bufsize: #缓冲区大小，默认为0，如果文件很大，可以修改此参数，一般默认即可

mode: #读写模式，默认为只读

openhook: #该钩子用于控制打开的所有文件，比如说编码方式等;

【常用函数】

fileinput.input() #返回能够用于for循环遍历的对象

fileinput.filename() #返回当前文件的名称

fileinput.lineno() #返回当前已经读取的行的数量（或者序号）

fileinput.filelineno() #返回当前读取的行的行号

fileinput.isfirstline() #检查当前行是否是文件的第一行

fileinput.isstdin() #判断最后一行是否从stdin中读取

fileinput.close() #关闭队列

【常见例子】

例子01: 利用fileinput读取一个文件所有行

>>> import fileinput

>>> for line in fileinput.input('data.txt'):

print line,

#输出结果

Python

Java

C/C++

Shell

命令行方式:

#test.py

import fileinput



for line in fileinput.input():

print fileinput.filename(),'|','Line Number:',fileinput.lineno(),'|: ',line



c:>python test.py data.txt

data.txt | Line Number: 1 |: Python

data.txt | Line Number: 2 |: Java

data.txt | Line Number: 3 |: C/C++

data.txt | Line Number: 4 |: Shell

例子02: 利用fileinput对多文件操作，并原地修改内容

#test.py

#---样本文件---

c:\Python27>type 1.txt

first

second



c:\Python27>type 2.txt

third

fourth

#---样本文件---

import fileinput



def process(line):

return line.rstrip() + ' line'



for line in fileinput.input(['1.txt','2.txt'],inplace=1):

print process(line)



#---结果输出---

c:\Python27>type 1.txt

first line

second line



c:\Python27>type 2.txt

third line

fourth line

#---结果输出---

命令行方式:

#test.py

import fileinput



def process(line):

return line.rstrip() + ' line'



for line in fileinput.input(inplace = True):

print process(line)



#执行命令

c:\Python27>python test.py 1.txt 2.txt

例子03: 利用fileinput实现文件内容替换，并将原文件作备份

#样本文件:

#data.txt

Python

Java

C/C++

Shell



#FileName: test.py

import fileinput



for line in fileinput.input('data.txt',backup='.bak',inplace=1):

print line.rstrip().replace('Python','Perl') #或者print line.replace('Python','Perl'),



#最后结果:

#data.txt

Python

Java

C/C++

Shell

#并生成:

#data.txt.bak文件

例子04: 利用fileinput将CRLF文件转为LF

import fileinput

import sys



for line in fileinput.input(inplace=True):

#将Windows/DOS格式下的文本文件转为Linux的文件

if line[-2:] == "\r\n":

line = line + "\n"

sys.stdout.write(line)

例子05: 利用fileinput对文件简单处理

#FileName: test.py

import sys

import fileinput



for line in fileinput.input(r'C:\Python27\info.txt'):

sys.stdout.write('=> ')

sys.stdout.write(line)



#输出结果

>>>

=> The Zen of Python, by Tim Peters

=>

=> Beautiful is better than ugly.

=> Explicit is better than implicit.

=> Simple is better than complex.

=> Complex is better than complicated.

=> Flat is better than nested.

=> Sparse is better than dense.

=> Readability counts.

=> Special cases aren't special enough to break the rules.

=> Although practicality beats purity.

=> Errors should never pass silently.

=> Unless explicitly silenced.

=> In the face of ambiguity, refuse the temptation to guess.

=> There should be one-- and preferably only one --obvious way to do it.

=> Although that way may not be obvious at first unless you're Dutch.

=> Now is better than never.

=> Although never is often better than *right* now.

=> If the implementation is hard to explain, it's a bad idea.

=> If the implementation is easy to explain, it may be a good idea.

=> Namespaces are one honking great idea -- let's do more of those!

例子06: 利用fileinput批处理文件

#---测试文件: test.txt test1.txt test2.txt test3.txt---

#---脚本文件: test.py---

import fileinput

import glob



for line in fileinput.input(glob.glob("test*.txt")):

if fileinput.isfirstline():

print '-'*20, 'Reading %s...' % fileinput.filename(), '-'*20

print str(fileinput.lineno()) + ': ' + line.upper(),





#---输出结果:

>>>

-------------------- Reading test.txt... --------------------

1: AAAAA

2: BBBBB

3: CCCCC

4: DDDDD

5: FFFFF

-------------------- Reading test1.txt... --------------------

6: FIRST LINE

7: SECOND LINE

-------------------- Reading test2.txt... --------------------

8: THIRD LINE

9: FOURTH LINE

-------------------- Reading test3.txt... --------------------

10: THIS IS LINE 1

11: THIS IS LINE 2

12: THIS IS LINE 3

13: THIS IS LINE 4

例子07: 利用fileinput及re做日志分析: 提取所有含日期的行

#--样本文件--

aaa

1970-01-01 13:45:30 Error: **** Due to System Disk spacke not enough...

bbb

1970-01-02 10:20:30 Error: **** Due to System Out of Memory...

ccc



#---测试脚本---

import re

import fileinput

import sys



pattern = '\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}'



for line in fileinput.input('error.log',backup='.bak',inplace=1):

if re.search(pattern,line):

sys.stdout.write("=> ")

sys.stdout.write(line)



#---测试结果---

=> 1970-01-01 13:45:30 Error: **** Due to System Disk spacke not enough...

=> 1970-01-02 10:20:30 Error: **** Due to System Out of Memory...

例子08: 利用fileinput及re做分析: 提取符合条件的电话号码

#---样本文件: phone.txt---

010-110-12345

800-333-1234

010-99999999

05718888888

021-88888888



#---测试脚本: test.py---

import re

import fileinput



pattern = '[010|021]-\d{8}' #提取区号为010或021电话号码，格式:010-12345678



for line in fileinput.input('phone.txt'):

if re.search(pattern,line):

print '=' * 50

print 'Filename:'+ fileinput.filename()+' | Line Number:'+str(fileinput.lineno())+' | '+line,



#---输出结果:---

>>>

==================================================

Filename:phone.txt | Line Number:3 | 010-99999999

==================================================

Filename:phone.txt | Line Number:5 | 021-88888888

>>>

例子09: 利用fileinput实现类似于grep的功能

import sys

import re

import fileinput



pattern= re.compile(sys.argv[1])

for line in fileinput.input(sys.argv[2]):

if pattern.match(line):

print fileinput.filename(), fileinput.filelineno(), line

$ ./test.py import.*re *.py

#查找所有py文件中，含import re字样的

addressBook.py 2 import re

addressBook1.py 10 import re

addressBook2.py 18 import re

test.py 238 import re

例子10: 利用fileinput做正则替换

#---测试样本: input.txt

* [Learning Python](#author:Mark Lutz)



#---测试脚本: test.py

import fileinput

import re



for line in fileinput.input():

line = re.sub(r'\* \[(.*)\]\(#(.*)\)', r'<h2 id="\2">\1</h2>', line.rstrip())

print(line)



#---输出结果:

c:\Python27>python test.py input.txt

<h2 id="author:Mark Lutz">Learning Python</h2>

例子11: 利用fileinput做正则替换，不同字模块之间的替换

#---测试样本:test.txt

[@!$First]&[*%-Second]&[Third]



#---测试脚本:test.py

import re

import fileinput



regex = re.compile(r'^([^&]*)(&)([^&]*)(&)([^&]*)')

#整行以&分割，要实现[@!$First]与[*%-Second]互换

for line in fileinput.input('test.txt',inplace=1,backup='.bak'):

print regex.sub(r'\3\2\1\4\5',line),



#---输出结果:

[*%-Second]&[@!$First]&[Third]

例子12: 利用fileinput根据argv命令行输入做替换

#---样本数据: host.txt

# localhost is used to configure the loopback interface

# when the system is booting. Do not change this entry.

127.0.0.1 localhost

192.168.100.2 www.test2.com

192.168.100.3 www.test3.com

192.168.100.4 www.test4.com



#---测试脚本: test.py

import sys

import fileinput



source = sys.argv[1]

target = sys.argv[2]

files = sys.argv[3:]



for line in fileinput.input(files,backup='.bak',openhook=fileinput.hook_encoded("gb2312")):

#对打开的文件执行中文字符集编码

line = line.rstrip().replace(source,target)

print line



#---输出结果:

c:\>python test.py 192.168.100 127.0.0 host.txt

#将host文件中，所有192.168.100转换为:127.0.0

127.0.0.1 localhost

127.0.0.2 www.test2.com

127.0.0.3 www.test3.com

127.0.0.4 www.test4.com