[英]Strange behavior from to_datetime()
I have really been having a tough time here.我在这里真的过得很艰难。
My DataFrame looks like this我的 DataFrame 看起来像这样
Purchase_Date Customer_ID Gender
0 2012-12-18 00:00:00 7223 F
1 2012-12-20 00:00:00 7841 M
2 2012-12-21 00:00:00 8374 F
My goal is to change the "Purchase Date" column from string to datetime object so that I can run a cohort analysis by applying this function to it:我的目标是将“购买日期”列从字符串更改为日期时间 object,以便我可以通过应用此 function 来运行群组分析:
def get_month(x): return dt.datetime(x.year, x.month, 1)
data['InvoiceMonth'] = data['Purchase_Date'].apply(get_month)
grouping = data.groupby('Customer_ID')['InvoiceMonth']
data['CohortMonth'] = grouping.transform('min')
the function returns error: 'str' object has no attribute 'year' I have tried the following functions and played with all arguments (dayfirst, yearfirst...) function 返回错误: 'str' object 没有属性 'year'我尝试了以下功能并使用了所有 arguments (dayfirst, yearfirst...)
data["Purchase_Date"] = pd.to_datetime(data["Purchase_Date"])
pd.to_datetime()
datetime.datetime.strptime()
I keep getting ValueError: day is out of range for month我不断收到ValueError: day is out of range for month
Please help out请帮忙
So, you were almost there:所以,你几乎在那里:
data["Purchase_Date"] = pd.to_datetime(data["Purchase_Date"])
data['InvoiceMonth'] = data["Purchase_Date"].dt.strftime("%Y-%m-01")
(Outputs month in object
format - you can convert it to datetime
by adding pd.to_datetime(...)
) (以
object
格式输出月份 - 您可以通过添加pd.to_datetime(...)
将其转换为datetime
时间)
Or alternatively - using your approach:或者 - 使用您的方法:
data["Purchase_Date"] = pd.to_datetime(data["Purchase_Date"])
import datetime as dt
def get_month(x): return dt.datetime(x.year, x.month, 1)
data['InvoiceMonth'] = data["Purchase_Date"].apply(get_month)
(Outputs month as datetime
) (输出月份为
datetime
)
Both will return, although I would highly recommend the first option:两者都会返回,尽管我强烈推荐第一个选项:
Purchase_Date Customer_ID Gender InvoiceMonth
0 2012-12-18 7223 F 2012-12-01
1 2012-12-20 7841 M 2012-12-01
2 2012-12-21 8374 F 2012-12-01
The error is related to get_month
because first you need to transform Purchase_Date
to a datetime serie:该错误与
get_month
有关,因为首先您需要将Purchase_Date
转换为日期时间系列:
import datetime as dt
data.Purchase_Date = pd.to_datetime(data.Purchase_Date, format='%Y-%m-%d %H:%M:%S')
data['Purchase_Date'].apply(get_month)
# 0 2012-12-01
# 1 2012-12-01
# 2 2012-12-01
You can also get the InvoiceMonth
using MonthBegin
so you don't have to declare get_month
您还可以使用
MonthBegin
获取InvoiceMonth
,因此您不必声明get_month
from pd.tseries.offset import MonthBegin
data.Purchase_Date = pd.to_datetime(data.Purchase_Date, format='%Y-%m-%d %H:%M:%S')
data['InvoiceMonth'] = data.Purchase_Date - MonthBegin(1)
data['InvoiceMonth']
# 0 2012-12-01
# 1 2012-12-01
# 2 2012-12-01
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