python - Pandas "if X not in DataFrame"总是抛出错误

Question

我有一个提示输入客户 ID 的简单应用。该应用程序使用输入来执行 SQL 语句，然后将结果集转换为数据框。

然后我检查提供的 ID 是否存在于数据框中；但是，即使 ID 确实存在，它也总是返回 false。打印输入和数据框确认输入的 ID 和数据框中的 ID 相同，列名也正确。

while True:
    customer_id = input("Insert an existing Customer ID")
    print(df)
    print(customer_id)
    customer_exists = customer_id in df.ID
    print(customer_exists)
    if not customer_exists:
        retry = input("No such customer. Try again? Y/N")
        if retry.upper() == 'Y':
            continue
        else:
            return None
    else:
        break

输出:

#The prompt
Insert an existing Customer ID: A1

#The dataframe
   ID  FNAME MNAME    LNAME  ADDRESS1 CUSTOMER_TYPE
0  A1  HELGA  None  PATHAKI  MICHIGAN        BRONZE

#The ID that was input by the user
A1

#the boolean result
False

这是怎么回事？

Answer 1

根据数据量，我建议你使用 np.isin()

import numpy as np

customer_id = input("Insert an existing Customer ID") #A1
sample= np.isin(customer_id, item2)
print(sample) # returns True