Python中fileinput模块介绍

发布时间:2017-09-12 15:24:49
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,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。

【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,站群软件,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:] == : 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

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