Python：基于“年”、“月”、“日”列实现一个包含星期几的列？

Question

我尝试创建一个包含星期几的新列：

df2019['Weekday']=pd.to_datetime(df2019['Year'],df2019['Month'],df2019['Day']).weekday()

我得到以下错误：

ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

谢谢

Answer 1

您可以这样做：

from datetime import datetime

def get_weekday(row):
    date_str = "{}-{}-{}".format(row["Year"], row["Month"], row["Day"])
    date = datetime.strptime(date_str, '%Y-%m-%d')
    return date.weekday()


df2019["weekday"] = df2019.apply(get_weekday, axis=1)

Answer 2

由于您的Timestamp已经是datetime格式，您可以执行以下操作：

df2019['weekday'] = df2019['Timestamp'].dt.weekday