1. 最基本的读文件方法:
#
File: readline-example-1.py
file =
open ( "sample.txt" )
while 1 :
line =
file .readline()
if
not line:
break
pass
# do something
|
一行一行得从文件读数据,显然比较慢;不过很省内存。
在我的机器上读10M的sample.txt文件,每秒大约读32000行
2. 用fileinput模块
#
File: readline-example-2.py
import fileinput
for line
in fileinput. input ( "sample.txt" ):
pass
|
写法简单一些,不过测试以后发现每秒只能读13000行数据,效率比上一种方法慢了两倍多……
3. 带缓存的文件读取
#
File: readline-example-3.py
file =
open ( "sample.txt" )
while 1 :
lines =
file .readlines( 100000 )
if
not lines:
break
for
line in lines:
pass #
do something
|
这个方法真的更好吗?事实证明,用同样的数据测试,它每秒可以读96900行数据!效率是第一种方法的3倍,第二种方法的7倍!
在Python 2.2以后,我们可以直接对一个file对象使用for循环读每行数据:
#
File: readline-example-5.py
file =
open ( "sample.txt" )
for line
in file :
pass
# do something
|
而在Python 2.1里,你只能用xreadlines迭代器来实现:
#
File: readline-example-4.py
file =
open ( "sample.txt" )
for line
in file .xreadlines():
pass
# do something
|
转自:http://www.cnblogs.com/xuxn/archive/2011/07/27/read-a-file-with-python.html
Python按行读文件对比,布布扣,bubuko.com
时间: 2024-10-26 20:23:10