轉載自:http://www.cnblogs.com/xuxn/archive/2011/07/27/read-a-file-with-python.html
1. 最基本的讀文件方法:
# File: readline-example-1.py file = open("sample.txt") while 1: line = file.readline() if not line: break pass # do something
一行一行得從文件讀數據,顯然比較慢;不過很省內存。
在我的機器上讀10M的sample.txt文件,每秒大約讀32000行
2. 用fileinput模塊
# File: readline-example-2.py import fileinput for line in fileinput.input("sample.txt"): pass
寫法簡單一些,不過測試以後發現每秒只能讀13000行數據,效率比上一種方法慢了兩倍多……
3. 帶緩存的文件讀取
# 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
這個方法真的更好嗎?事實證明,用同樣的數據測試,它每秒可以讀96900行數據!效率是第一種方法的3倍,第二種方法的7倍!
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在Python 2.2以後,我們可以直接對一個file對象使用for循環讀每行數據:
# File: readline-example-5.py file = open("sample.txt") for line in file: pass # do something 而在Python 2.1裏,你只能用xreadlines迭代器來實現: ? # File: readline-example-4.py file = open("sample.txt") for line in file.xreadlines(): pass # do something
轉載自:http://www.cnblogs.com/xuxn/archive/2011/07/27/read-a-file-with-python.html