python - 查找之前不存在的 customer_id

Question

我想过滤 customer_id's以前的数据中不存在的所有 new_customer_ids在 2020-01-10 上是新的，但在 2020-01-01 上不存在
main_df

date          customer_id   amount_spent 
2020-01-01    24            123
2020-01-10    24            145
2020-01-01    58             89
2020-01-10    58             67
2020-01-01    98             34
2020-01-10    99             86
2020-01-10    67            140
2020-01-10    32            321
2020-01-10    75             76

输出_df

new_customer_id  amount_spent 
32           321
75            76
67           140

我曾尝试在 Pandas 中使用 shift 功能，但这对我不起作用
编辑

df = pd.DataFrame([["2020-01-01",24,123],
["2020-01-10",24,145],
["2020-01-01",58,89],
["2020-01-10",58,67],
["2020-01-01",98,34],
["2020-01-10",98,86],
["2020-01-10",67,140],
["2020-01-10",32,321],
["2020-01-10",75,76]],columns = ["date","customer_id","amount_spent" ])

Answer 1

IIUC你可以获得customer_id存在于 2020-01-01 ，然后过滤掉它们:

s = df.loc[df["date"]=="2020-01-01", "customer_id"]

print (df[~df["customer_id"].isin(s)])

         date  customer_id  amount_spent
5  2020-01-10           99            86
6  2020-01-10           67           140
7  2020-01-10           32           321
8  2020-01-10           75            76