fileinput子產品可以對一個或多個檔案中的内容進行疊代、周遊等操作。
該子產品的input()函數有點類似檔案readlines()方法，差別在于:
前者是一個疊代對象，即每次隻生成一行，需要用for循環疊代。
後者是一次性讀取所有行。在碰到大檔案的讀取時，前者無疑效率更高效。
用fileinput對檔案進行循環周遊，格式化輸出，查找、替換等操作，非常友善。
【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]]]]]])
【預設格式】
fileinput.input (files=None, inplace=False, backup='', bufsize=0, mode='r', openhook=None)
files: #檔案的路徑清單，預設是stdin方式，多檔案['1.txt','2.txt',...]
inplace: #是否将标準輸出的結果寫回檔案，預設不取代
backup: #備份檔案的擴充名，隻指定擴充名，如.bak。如果該檔案的備份檔案已存在，則會自動覆寫。
bufsize: #緩沖區大小，預設為0，如果檔案很大，可以修改此參數，一般預設即可
mode: #讀寫模式，預設為隻讀
openhook: #該鈎子用于控制打開的所有檔案，比如說編碼方式等;
【常用函數】
fileinput.input() #傳回能夠用于for循環周遊的對象
fileinput.filename() #傳回目前檔案的名稱
fileinput.lineno() #傳回目前已經讀取的行的數量(或者序号)
fileinput.filelineno() #傳回目前讀取的行的行号
fileinput.isfirstline() #檢查目前行是否是檔案的第一行
fileinput.isstdin() #判斷最後一行是否從stdin中讀取
fileinput.close() #關閉隊列
【常見例子】
例子01: 利用fileinput讀取一個檔案所有行
>>> import fileinput
>>> for line in fileinput.input('data.txt'):
print line,
#輸出結果
Python
Java
C/C++
Shell
指令行方式:
#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對多檔案操作，并原地修改内容
#test.py
#---樣本檔案---
c:\Python27>type 1.txt
first
second
c:\Python27>type 2.txt
third
fourth
#---樣本檔案---
import fileinput
def process(line):
return line.rstrip() + ' line'
for line in fileinput.input(['1.txt','2.txt'],inplace=1):
print process(line)
#---結果輸出---
c:\Python27>type 1.txt
first line
second line
c:\Python27>type 2.txt
third line
fourth line
#---結果輸出---
指令行方式:
#test.py
import fileinput
def process(line):
return line.rstrip() + ' line'
for line in fileinput.input(inplace = True):
print process(line)
#執行指令
c:\Python27>python test.py 1.txt 2.txt
例子03: 利用fileinput實作檔案内容替換，并将原檔案作備份
#樣本檔案:
#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'),
#最後結果:
#data.txt
Python
Java
C/C++
Shell
#并生成:
#data.txt.bak檔案
#其效果等同于下面的方式
import fileinput
for line in fileinput.input():
print 'Tag:',line,
#---測試結果:
d:\>python Learn.py < data.txt > data_out.txt
例子04: 利用fileinput将CRLF檔案轉為LF
import fileinput
import sys
for line in fileinput.input(inplace=True):
#将Windows/DOS格式下的文本檔案轉為Linux的檔案
if line[-2:] == "\r\n":
line = line + "\n"
sys.stdout.write(line)
例子05: 利用fileinput對檔案簡單處理
#FileName: test.py
import sys
import fileinput
for line in fileinput.input(r'C:\Python27\info.txt'):
sys.stdout.write('=> ')
sys.stdout.write(line)
#輸出結果
>>>
=> 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批處理檔案
#---測試檔案: test.txt test1.txt test2.txt test3.txt---
#---腳本檔案: 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(),
#---輸出結果:
>>>
-------------------- 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
#--樣本檔案--
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
#---測試腳本---
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)
#---測試結果---
=> 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: 提取符合條件的電話号碼
#---樣本檔案: phone.txt---
010-110-12345
800-333-1234
010-99999999
05718888888
021-88888888
#---測試腳本: test.py---
import re
import fileinput
pattern = '[010|021]-\d{8}' #提取區号為010或021電話号碼，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,
#---輸出結果:---
>>>
==================================================
Filename:phone.txt | Line Number:3 | 010-99999999
==================================================
Filename:phone.txt | Line Number:5 | 021-88888888
>>>
例子09: 利用fileinput實作類似于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檔案中，含import re字樣的
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做正則替換
#---測試樣本: input.txt
* [Learning Python](#author:Mark Lutz)
#---測試腳本: test.py
import fileinput
import re
for line in fileinput.input():
line = re.sub(r'\*
(.∗)
#(.*)', r'
\1
', line.rstrip())
print(line)
#---輸出結果:
c:\Python27>python test.py input.txt
Learning Python
例子11: 利用fileinput做正則替換，不同字子產品之間的替換
#---測試樣本:test.txt
[@!$First]&[*%-Second]&[Third]
#---測試腳本:test.py
import re
import fileinput
regex = re.compile(r'^([^&]*)(&)([^&]*)(&)([^&]*)')
#整行以&分割，要實作[@!$First]與[*%-Second]互換
for line in fileinput.input('test.txt',inplace=1,backup='.bak'):
print regex.sub(r'\3\2\1\4\5',line),
#---輸出結果:
[*%-Second]&[@!$First]&[Third]
例子12: 利用fileinput根據argv指令行輸入做替換
#---樣本資料: 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
#---測試腳本: 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")):
#對打開的檔案執行中文字元集編碼
line = line.rstrip().replace(source,target)
print line
#---輸出結果:
c:\>python test.py 192.168.100 127.0.0 host.txt
#将host檔案中，所有192.168.100轉換為: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