import pandas as pd

df = pd.DataFrame(columns=["col1"])  # shape[0] == 0

 # df["col2"] = df["col1"].apply(sum) * 1  # ok

# sum(*[1,2])  # TypeError: 'int' object is not iterable
df[["col1"]].apply(lambda row: sum(*row), axis=1)  # ok

# 哪个会出错？
import pandas as pd


df = pd.DataFrame()
df["col1"] = ["col1"]*2
df["col2"] = "col2"
df.index = [f"ind{i}" for i in df.index]


for index, data in df.iterrows():
    print(index)  # label
    print(data)
import pandas as pd


df = pd.DataFrame()
df["客户代码"] = ["客户代码1", "客户代码2", "客户代码2", "客户代码3"]
df["公司代码货币价值"] = [1, 2, None, 3]


# None
# 赋值
df["公司代码货币价值"] = df.apply(lambda row: row["公司代码货币价值"] if row["客户代码"] != "客户代码2" else row["公司代码货币价值"] - .1, axis=1)
print(df)