创建月份和年份列中没有天数的日期 pandas dataframe

Question

1. I want to Create a new column, called 'Month_Year', using lambda function. Its values should be: '01-01-2020' for January, 2020 and '01-02-2020' for February 2020 and so on. The data set contains only month:{jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec} obj dtype. I have to convert this month_names to month_numbers. dataset also has year column with data from 2020 - 2022 int dtype. I want to create dates for this dataset using Month and Year. enter image description here

{year = pd.to_datetime(df1.Year, format='%Y').dt.year
df1['Month'] = pd.to_datetime(df1.Month, format='%b').dt.month}


cal = calendar.Calendar()
for i in cal.itermonthdays3(year=year, month=month):
    print(i)

/// Error: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
{2nd way}`

def date_iter(year, month):
    for i in range(1, calendar.monthrange(year, month) + 1):
        yield date(year, month, i)

for d in date_iter(year, month):
    print(d)

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

How can I create dates column based on month and year Column?

Answer 1

Try:

df["Month_Year"] = pd.to_datetime(df["Month"] + "-" + df["Year"].astype(str))
print(df)

Prints:

   Month  Year Month_Year
0    Jan  2020 2020-01-01
1    Feb  2021 2021-02-01
2    Mar  2022 2022-03-01
3    Apr  2020 2020-04-01
4    May  2021 2021-05-01
5    Jun  2022 2022-06-01
6    Jul  2020 2020-07-01
7    Aug  2021 2021-08-01
8    Sep  2022 2022-09-01
9    Oct  2020 2020-10-01
10   Nov  2021 2021-11-01
11   Dec  2022 2022-12-01

---

Input dataframe:

   Month  Year
0    Jan  2020
1    Feb  2021
2    Mar  2022
3    Apr  2020
4    May  2021
5    Jun  2022
6    Jul  2020
7    Aug  2021
8    Sep  2022
9    Oct  2020
10   Nov  2021
11   Dec  2022