如何比较两个不同数据框架的两列并添加新的结果列

Question

我有两个数据帧

第一个DF1: (7 x 3)

数量3

Answer 1

好了，合并id和item:

comb = pd.merge(DF1, DF2, on=['ID', 'Item'], how='left').rename(columns={'Qty_x': 'DF1_Qty','Qty_y': 'DF2_Qty'})
comb = comb.fillna(0)
comb['Qty_new'] = comb['DF1_Qty'] - comb['DF2_Qty']