Combine year, month and day in Python to create a date

Solution

You could use datetime.datetime along with .apply().

import datetime

d = datetime.datetime(2020, 5, 17)
date = d.date()

For pandas.to_datetime(df)

It looks like your code is fine. See pandas.to_datetime documentation and How to convert columns into one datetime column in pandas?.

df = pd.DataFrame({'year': [2015, 2016],
                   'month': [2, 3],
                   'day': [4, 5]})
pd.to_datetime(df[["year", "month", "day"]])

Output:

0   2015-02-04
1   2016-03-05
dtype: datetime64[ns]

What if your YEAR, MONTH and DAY columns have different headers?

Let's say your YEAR, MONTH and DAY columns are labeled as yy, mm and dd respectively. And you prefer to keep your column names unchanged. In that case you could do it as follows.

import pandas as pd

df = pd.DataFrame({'yy': [2015, 2016],
                   'mm': [2, 3],
                   'dd': [4, 5]})
df2 = df[["yy", "mm", "dd"]].copy()
df2.columns = ["year", "month", "day"]
pd.to_datetime(df2)

Output:

0   2015-02-04
1   2016-03-05
dtype: datetime64[ns]

Here is a two liner:

df['dateInt']=df['year'].astype(str) + df['month'].astype(str).str.zfill(2)+ df['day'].astype(str).str.zfill(2)
df['Date'] = pd.to_datetime(df['dateInt'], format='%Y%m%d')

Output

    year  month day dateInt     Date
0   2015    5   20  20150520    2015-05-20
1   2016    6   21  20160621    2016-06-21
2   2017    7   22  20170722    2017-07-22
3   2018    8   23  20180823    2018-08-23
4   2019    9   24  20190924    2019-09-24

Tags:

Python

Datetime

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