# 找出次数最多的元素-Counter

代码：

```python
from collections import Counter

words=['look','info','my','AAA','look','my','AAA','the','AAA','the','AAA','the','eyes','not','BBB','the',
      'AAA','dont','BBB','around','the','AAA','look','into','BBB','AAA','under']

words_counts=Counter(words)
#最多频率的3个元组
top_3=words_counts.most_common(3)
print(words_counts)
print()
print('top_3:\n',top_3)
```

结果：

```python
Counter({'AAA': 7, 'the': 5, 'look': 3, 'BBB': 3, 'my': 2, 'info': 1, 'eyes': 1, 'not': 1, 'dont': 1, 'around': 1, 'into': 1, 'under': 1})

top_3:
 [('AAA', 7), ('the', 5), ('look', 3)]
```

视频：

```
none
```

## Counter()其它操作

代码：

```python
from collections import Counter

print('c.subtract(d)')
c = Counter(a=4, b=2, c=0, d=-2)
print(c)
d = Counter(a=1, b=2, c=3, d=4,e=11)
print(d)
c.subtract(d)#相减
print(c)


print('c+d','-'*50)
c = Counter(a=4, b=2, c=0, d=-2,e=11)
print(c)
d = Counter(a=1, b=2, c=3, d=4)
print(d)
print(c + d) #相加，舍去非正数

print('c-d','-'*50)
c = Counter(a=4, b=2, c=0, d=-2,e=11)
print(c)
d = Counter(a=1, b=2, c=3, d=4)
print(d)
print(c - d) #相减，舍去非正数

print('c&d','-'*50)
c = Counter(a=4, b=2, c=0, d=-2,e=11)
print(c)
d = Counter(a=1, b=2, c=3, d=4)
print(c & d) #交集，取小的那个，舍去非正数

print('c|d','-'*50)
c = Counter(a=4, b=2, c=0, d=-2,e=11)
print(c)
d = Counter(a=1, b=2, c=3, d=4)
print(d)
print(c | d) #并集，取大的那个，舍去非正数


print('c.update(d)','-'*50)
c = Counter(a=4, b=2, c=0, d=-2,e=11)
print(c)
d = Counter(a=1, b=2, c=3, d=4)
print(d)
c.update(d)#更新Counter，对于已有的元素计数加对应新的数量，对没有的元素进行添加
print(c)


print('-'*50)
print(c.items())
print(list(c))
print(set(c))
print(dict(c))
print(c.values())
```

结果：

```python
c.subtract(d)
Counter({'a': 4, 'b': 2, 'c': 0, 'd': -2})
Counter({'e': 11, 'd': 4, 'c': 3, 'b': 2, 'a': 1})
Counter({'a': 3, 'b': 0, 'c': -3, 'd': -6, 'e': -11})
c+d --------------------------------------------------
Counter({'e': 11, 'a': 4, 'b': 2, 'c': 0, 'd': -2})
Counter({'d': 4, 'c': 3, 'b': 2, 'a': 1})
Counter({'e': 11, 'a': 5, 'b': 4, 'c': 3, 'd': 2})
c-d --------------------------------------------------
Counter({'e': 11, 'a': 4, 'b': 2, 'c': 0, 'd': -2})
Counter({'d': 4, 'c': 3, 'b': 2, 'a': 1})
Counter({'e': 11, 'a': 3})
c&d --------------------------------------------------
Counter({'e': 11, 'a': 4, 'b': 2, 'c': 0, 'd': -2})
Counter({'b': 2, 'a': 1})
c|d --------------------------------------------------
Counter({'e': 11, 'a': 4, 'b': 2, 'c': 0, 'd': -2})
Counter({'d': 4, 'c': 3, 'b': 2, 'a': 1})
Counter({'e': 11, 'a': 4, 'd': 4, 'c': 3, 'b': 2})
c.update(d) --------------------------------------------------
Counter({'e': 11, 'a': 4, 'b': 2, 'c': 0, 'd': -2})
Counter({'d': 4, 'c': 3, 'b': 2, 'a': 1})
Counter({'e': 11, 'a': 5, 'b': 4, 'c': 3, 'd': 2})
--------------------------------------------------
dict_items([('a', 5), ('b', 4), ('c', 3), ('d', 2), ('e', 11)])
['a', 'b', 'c', 'd', 'e']
{'c', 'e', 'b', 'a', 'd'}
{'a': 5, 'b': 4, 'c': 3, 'd': 2, 'e': 11}
dict_values([5, 4, 3, 2, 11])
```

视频：

```
none
```


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