1
2 --------------------对象用Counter-------------------------------------------------------------
3
4 dc={"james":4,"kim":3,"marry":5,"bill":6}
5 from collections import Counter
6 counts=Counter(dc)
7 counts
8 >>Counter({'bill': 6, 'marry': 5, 'james': 4, 'kim': 3})
9 counts.most_common(3)
10 >>[('bill', 6), ('marry', 5), ('james', 4)]
11
12
13 #-------------------数组用sorted operator ----------------------------------------------
14 dc=[{'name':"james",'v':4},{'name':"kim",'v':3},{'name':"marry",'v':5},{'name':"bill",'v':6}]
15 import operator
16 print dc
17 >>[{'name': 'bill', 'v': 6}, {'name': 'james', 'v': 4}, {'name': 'kim', 'v': 3}, {'name': 'marry', 'v': 5}]
18 print sorted(dc,key=operator.itemgetter("v"),reverse=True)
19 >>[{'name': 'bill', 'v': 6}, {'name': 'marry', 'v': 5}, {'name': 'james', 'v': 4}, {'name': 'kim', 'v': 3}]
1 # ----Counter 可用于频次统计
2 ar=[1,2,2,3,5,6,6,5,5,6]
3 counts=Counter(ar)
4 print counts
5 >>Counter({5: 3, 6: 3, 2: 2, 1: 1, 3: 1})
6 #输出是个对象
7 for k in counts:
8 print str(k)+" "+str(counts[k])
9 >>
10 1 1
11 2 2
12 3 1
13 5 3
14 6 3
15
16 print counts.most_common()
17 >>[(5, 3), (6, 3), (2, 2), (1, 1), (3, 1)]
