DataFrame.value_counts

DataFrame.value_counts(subset=None, normalize=False, sort=True, ascending=False)
返回一个包含DataFrame中唯一行个数的Series。

Parameters

subset	计算唯一组合时要使用的列
normalize	True：返回比例；False：返回频率
sort	是否按频率排序
ascending	是否按升序排序
dropna	是否去掉包含NA值的行

Example

import pandas as pd
df = pd.DataFrame({'site':['google', 'baidu', 'wiki', 'google'],
                    'age':[18, 39, 22, 18],
                    'price': [1.0, 2.0, 3.0, 1.0],
                    'color': ['red', 'black', None, 'red']})
df.value_counts(normalize=True)
------------------------------------------------------------------
site    age  price  color
google  18   1.0    red      0.666667
baidu   39   2.0    black    0.333333
dtype: float64

Example

import pandas as pd
df = pd.DataFrame({'site':['google', 'baidu', 'wiki', 'google'],
                    'age':[18, 39, 22, 18],
                    'price': [1.0, 2.0, 3.0, 1.0],
                    'color': ['red', 'black', None, 'red']})
df.value_counts(normalize=False)
---------------------------------------------------------------------
site    age  price  color
google  18   1.0    red      2
baidu   39   2.0    black    1
dtype: int64

Example

import pandas as pd
df = pd.DataFrame({'site':['google', 'baidu', 'wiki', 'google'],
                    'age':[18, 39, 22, 18],
                    'price': [1.0, 2.0, 3.0, 1.0],
                    'color': ['red', 'black', None, 'red']})
df.value_counts('site')
----------------------------------------------------------------
site
google    2
wiki      1
baidu     1
dtype: int64