Python_collections_Counter计数器部分功能介绍

Posted 2021-01-04 Vera_y

counter():是对字典的补充，用来方便的计数，继承了字典

import collections
obj = collections.Counter(‘yigbavfsdcfdsfdsd‘)
print(obj)

结果：
    Counter({‘d‘: 4, ‘f‘: 3, ‘s‘: 3, ‘y‘: 1, ‘i‘: 1, ‘g‘: 1, ‘b‘: 1, ‘a‘: 1, ‘v‘: 1, ‘c‘: 1})

x.most_common():按照counter计数，以列表的形式降序返回前n项元素

import collections
obj = collections.Counter(‘yigbavfsdcfdsfdsd‘)
print(obj)
print(obj.most_common(4))

结果：
    Counter({‘d‘: 4, ‘f‘: 3, ‘s‘: 3, ‘y‘: 1, ‘i‘: 1, ‘g‘: 1, ‘b‘: 1, ‘a‘: 1, ‘v‘: 1, ‘c‘: 1})
　　[(‘d‘, 4), (‘f‘, 3), (‘s‘, 3), (‘y‘, 1)]

x.element():按照Counter的计数返回元素

import collections
obj = collections.Counter(‘yigbavfsdcfdsfdsd‘)
for k in obj.elements():
    print(k)

结果：
y
i
g
b
a
v
f
f
f
s
s
s
d
d
d
d
c

x.update():更新计数器，在原来的基础上增加或者修改

x.subtract():在原计数器的基础上减少元素，没有的记为负

import collections
obj = collections.Counter([‘33‘, ‘we‘, ‘33‘, ‘11‘])
print(obj)
obj.update([‘zhao‘, ‘11‘, ‘qq‘, ‘11‘, ])
print(obj)
obj.subtract([‘zhao‘, ‘11‘, ‘qq‘, ‘lihao‘, ])
print(obj)

结果：

Counter({‘33‘: 2, ‘we‘: 1, ‘11‘: 1})

Counter({‘11‘: 3, ‘33‘: 2, ‘we‘: 1, ‘zhao‘: 1, ‘qq‘: 1})

  Counter({‘33‘: 2, ‘11‘: 2, ‘we‘: 1, ‘zhao‘: 0, ‘qq‘: 0, ‘lihao‘: -1})