将最近一年的值添加到上一年最后一个月的 Pandas dataframe groupby year

如何解决将最近一年的值添加到上一年最后一个月的 Pandas dataframe groupby year

我想在这个示例数据框中按年份分组，如果“严重病例 U5”的总和 == 0 和“Num_U5_Received_Severe_Treatment”的总和大于 0，我想将“Num_U5_Received_Severe_Treatment”的总和添加到上一年的最后一个月。查看我的数据：

data = [[2020,11,1,1],[2020,12,2,2],[2021,0],1]]
df = pd.DataFrame(data,columns = ['year','month','Severe cases U5','Num_U5_Received_Severe_Treatment'])

我首先写下您在下面看到的内容（不确定如何索引 groupby 对象），但一直收到此错误：TypeError：元组索引必须是整数或切片，而不是 str

for group in df.groupby('year'):
    if group['Severe cases U5'].sum() == 0 and group['Num_U5_Received_Severe_Treatment'].sum() > 0:
         pre_year = group['year'] - 1

更新：我想出了组迭代。现在需要弄清楚行迭代。代码的那部分不起作用。见下文：

for year,group in df.groupby('year'):
        if (group['Severe cases U5'].sum() == 0 and group['Num_U5_Received_Severe_Treatment'].sum() > 0):
        
            year_current = np.unique(group['year'])[0] -1
            excess_death = group['Num_U5_Received_Severe_Treatment'].sum()
            group['Num_U5_Received_Severe_Treatment'] = 0
            print(excess_death)
            print(year_current)
    for month_row,row in group.iterrows():  
            if (row['year'] == year and row['month'] == 12): #not working but what i am trying to do
                    row['Num_U5_Received_Severe_Treatment'] =+ excess_death
                    print(row['Num_U5_Received_Severe_Treatment'])

解决方法

我终于明白了！庞大的解决方案，但它有效。

data = [[2020,11,1,1],[2020,12,2,2],[2021,0],1]]
df = pd.DataFrame(data,columns = ['year','month','Severe cases U5','Num_U5_Received_Severe_Treatment'])

for year,group in df.groupby('year'):
        if (group['Severe cases U5'].sum() == 0 and group['Num_U5_Received_Severe_Treatment'].sum() > 0):
        
            year_current = np.unique(group['year'])[0] -1
            excess_death = group['Num_U5_Received_Severe_Treatment'].sum()
            for month_row,row in group.iterrows():
                if (row['Num_U5_Received_Severe_Treatment'] > 0):
                      df.loc[month_row,'Num_U5_Received_Severe_Treatment'] = 0
           
      
        
for year,group in df.groupby('year'):
        for month_row,row in group.iterrows():
            if (row['year'] == year_current and row['month'] == 12):
            #not working but what i am trying to do
                 death_previous=row['Num_U5_Received_Severe_Treatment'] + excess_death
                 df.loc[month_row,'Num_U5_Received_Severe_Treatment'] = death_previous
df