计算每天来自两列或更多列熊猫的不重复事件

编程问答 2022-08-14

问题描述

我想从两列中计算每天出现的唯一名称：

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.load("Image Url")
.noplaceHolder()
.into(iv);

这样我可以获得一系列或相似的内容：

df = pd.DataFrame({
    'ColA':['john wick','bloody mary','peter pan','jeff bridges','billy boy'],'ColB':['bloody mary','billy boy','john wick'],'date':['2000-01-01','2000-01-01','2000-01-03','2000-01-03'],})
datetime_series = pd.to_datetime(df['date'])
datetime_index = pd.DatetimeIndex(datetime_series.values)
df2 = df.set_index(datetime_index)
df2.drop('date',axis=1,inplace=True)
df2
Out[746]: 
                    ColA          ColB
2000-01-01  john wick     bloody mary 
2000-01-01  bloody mary   jeff bridges
2000-01-03  peter pan     billy boy   
2000-01-03  jeff bridges  billy boy   
2000-01-03  billy boy     john wick

解决方法

将DataFrame.stack与DataFrameGroupBy.nunique和最后Series.to_frame一起使用：

df3 = df2.stack().groupby(level=0).nunique().to_frame(name='unique occurrences of names')
print (df3)
            unique occurrences of names
2000-01-01                            3
2000-01-03                            4

或用DataFrame.melt替代：

df3 = (df2.reset_index()
          .melt('index')
          .groupby('index')['value']
          .nunique()
          .to_frame(name='unique occurrences of names'))
countpandaspythonunique