test.txt內容如下：
1|name1|agg1|add1|phone1|card1|
2|name2|agg2|add2|phone2|card2|

如何提取第4列的內容，即add1、add2

 1 def iterdatainfile(filename, spliter=‘\t‘):
 2     with open(filename, ‘rt‘) as handle:
 3         for ln in handle:
 4             yield ln.split(spliter)
 5  
 6 focue, LF = 3, ‘\n‘  #LF = 3：取第4列
 

 7 with open("output.txt", ‘wt‘) as handle:
 8     handle.writelines([row[focue] + LF
 9                        for row in iterdatainfile(‘test.txt‘,spliter=‘|‘)])
10 
11 # 下面是顯示提取到的內容
12 txtstr = open(‘output.txt‘)
13 a = txtstr.read()
14 print(a)

從規則文本文件中提取列字段