Python中fileinput模块介绍

时间：2021-11-03 00:19:45

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.pyimport fileinputdef 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
#其效果等同于下面的方式import fileinputfor line in fileinput.input():    print 'Tag:',line,#---测试结果:   d:\>python Learn.py < data.txt > data_out.txt
 

    

  • 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





 

 

 

 



 


 

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