下面的代码抛出ValueError: unknown type str32 for string comparison：

import pandas as pd

# Loading in some bigger data from Kaggle https://www.kaggle.com/dgomonov/new-york-city-airbnb-open-data
# data and code file included in zip to make it easy
df = pd.read_csv("AB_NYC_2019.csv")

print(df == "x")  # throws ValueError

看来最后一行代码是合法的。做错了什么？