Pyhton 学习总结 21 ：fileinput模块
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，需要用for循环迭代，后者是一次性读取所有行。
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。
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---
#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:] == : line = line + 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: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
#---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.* fileinput *.py
