《用Python玩转数据》第2周学习笔记(Part1)

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1、Python之文件操作：http://blog.chinaunix.net/uid-26602509-id-3503138.html

2、正则表达式教程：
http://deerchao.net/tutorials/regex/regex.htm
http://www.java3z.com/cwbwebhome/article/article8/Regex/Java.Regex.Tutorial.html
http://www.cnblogs.com/huxi/archive/2010/07/04/1771073.html

如果要处理数据，正则表达式是必须要熟练掌握的。现在两眼一抹黑，看不懂下面的代码是如何通过正则表达式获取数据的：

import urllibimport redStr = urllib.urlopen('http://finance.yahoo.com/q/cp?s=%5EDJI+Components').read()m = re.findall('<tr><td class=\"yfnc_tabledata1\"><b><a href=\".*?\">\(.*?)</a></b></td><td class=\"yfnc_tabledata1\">(.*?)</td>.*?<b>(.*?)</b>.*?</tr>', dStr)if m:    print m    print '\n'    print len(m)else:      print 'not match'

暂停第2周学习，先把正则表达式搞定。

3、编程小练习：

创建一个文件src.txt，文件内容为：
How many seas must a white dove sail
Before she sleeps in the sand
将src.txt的内容复制到文件dest.txt中，并在dest.txt文件头部添加另两行字符串，添加后dest.txt文件中的内容为：
How many roads must a man walk down
Before they call him a man
How many seas must a white dove sail
Before she sleeps in the sand

f1 = open(r'D:\src.txt', 'w+')f1.writelines('How many seas must a white dove sail\nBefore she sleeps in the sand\n')f1.seek(0, 0)f2 = open(r'D:\dest.txt', 'w')f2.writelines('How many roads must a man walk down\n')f2.writelines('Before they call him a man\n')words = f1.readlines()for w in words:    f2.writelines(w)f1.close()f2.close()

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