python中fileinput模块的使用方法

python中fileinput模块是如何来使用的呢?下面的内容将会通过具体的实例来演示python中fileinput模块的使用方法及相关技巧:

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】

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import fileinput

for line in fileinput.input():

    process(line)

【基本格式】

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

【默认格式】

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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】

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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

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>>> 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:

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#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

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#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:

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#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

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#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
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#其效果等同于下面的方式

import fileinput

for 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

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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:] == "rn":

        line = line + "n"

    sys.stdout.write(line)

例子05: 利用fileinput对文件简单处理

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#FileName: test.py

import sys

import fileinput



for line in fileinput.input(r'C:Python27info.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

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#---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

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#--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

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#---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

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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

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#---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'*

(.&#8727;)

#(.*)'
, 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

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#---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'32145',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

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#---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

python中fileinput模块就是这样,欢迎大家参考。。。。

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