如何找出 python list 中有重复的项

 

 

比较容易记忆的是用内置的set
l1 = ['b','c','d','b','c','a','a']
l2 = list(set(l1))
print l2

还有一种据说速度更快的，没测试过两者的速度差别
l1 = ['b','c','d','b','c','a','a']
l2 = {}.fromkeys(l1).keys()
print l2

这两种都有个缺点，祛除重复元素后排序变了：
['a', 'c', 'b', 'd']



如果想要保持他们原来的排序：

用list类的sort方法
l1 = ['b','c','d','b','c','a','a']
l2 = list(set(l1))
l2.sort(key=l1.index)
print l2
也可以这样写
l1 = ['b','c','d','b','c','a','a']
l2 = sorted(set(l1),key=l1.index)
print l2


也可以用遍历
l1 = ['b','c','d','b','c','a','a']
l2 = []
for i in l1:
if not i in l2:
l2.append(i)
print l2
上面的代码也可以这样写
l1 = ['b','c','d','b','c','a','a']
l2 = []
[l2.append(i) for i in l1 if not i in l2]
print l2


这样就可以保证排序不变了：
['b', 'c', 'd', 'a'] 

 

 1 #!/usr/bin/env python
 2 # coding:   utf-8
 3 
 4 import os
 5 import sys
 6 import string
 7 import operator
 8 import re
 9 import threading
10 import csv
11 
12 from time import sleep,ctime
13 from collections import defaultdict
14 from collections import Counter
15 
16 
17 def test_01():
18     #content  ==>  ###pos=350143600,pts=2676718###
19     #filename="F:\\yingc\\work\\goxceed-dvbs-hd\\6605\\solution\\aa"
20     filename="./aa"
21     pos=-1
22     dts=-1
23     poslist=[]
24     dtslist=[]
25     
26     str1="###pos="
27     str2=",pts="
28     
29     f = open(filename)
30     for line in f:
31         aa=line[0:len(str1)]
32         if aa == str1:
33             pos=line[len(str1):line.index(str2)]
34             dts=line[line.index(str2)+len(str2):len(line)-3-1]
35             poslist.append(pos)
36             dtslist.append(dts)
37     f.close()
38     
39     #s=[11,22,11,44,22,33]
40     d = defaultdict(list)
41     for k,va in [(v,i) for i,v in enumerate(poslist)]:
42         d[k].append(va)
43     #print  d.items()
44     count=0
45     for value in d.items():
46         if len(value[1])>1:
47             print value
48             count=count+1
49     print "poslen:"+str(len(poslist))+",dtslen"+str(len(dtslist))
50     print str(len(d))+","+str(count)
51 
52     #d = defaultdict(list)
53     #for k,va in [(v,i) for i,v in enumerate(dtslist)]:
54     #    d[k].append(va)
55     ##print  d.items()
56     #for value in d.items():
57     #    if len(value[1])>1:
58     #        print value
59 
60     #print Counter([11,22,11,44,22,33])
61 
62 
63 
64 
65 if __name__ == "__main__":
66     test_01()
67     print "finish"
68

 

aa文件中的内容如：

###pos=1349796,pts=15015###
###pos=2337820,pts=27986###
###pos=2705098,pts=29988###
###pos=6660200,pts=54721###
###pos=8055314,pts=61061###
###pos=8871800,pts=65315###
###pos=9503420,pts=68401###
###pos=12855218,pts=88338###
###pos=14253082,pts=98765###
###pos=15813764,pts=109192###
###pos=15813764,pts=109192###
###pos=15813764,pts=109192###
###pos=15813764,pts=109192###
###pos=16056146,pts=110735###
###pos=16394580,pts=113988###
###pos=17011532,pts=119911###
###pos=17257542,pts=122372###
###pos=17417974,pts=124040###
###pos=17816976,pts=128169###
###pos=17993398,pts=129838###
###pos=18302190,pts=132215###
###pos=19166088,pts=139055###
###pos=19675276,pts=143059###
###pos=19994992,pts=146146###
一个奔跑的程序员