Pandas: Convert year and day of year into a single datetime column of a dataframe

Last update on May 02 2025 12:54:59 (UTC/GMT +8 hours)

12. Convert Year and Day of Year to Datetime

Write a Pandas program to convert year and day of year into a single datetime column of a dataframe.

Sample Solution:

Python Code :

import pandas as pd
data = {\
"year": [2002, 2003, 2015, 2018],
"day_of_the_year": [250, 365, 1, 140]
}
df = pd.DataFrame(data)
print("Original DataFrame:")
print(df)
df["combined"] = df["year"]*1000 + df["day_of_the_year"]
df["date"] = pd.to_datetime(df["combined"], format = "%Y%j")
print("\nNew DataFrame:")
print(df)

Sample Output:

Original DataFrame:
   year  day_of_the_year
0  2002              250
1  2003              365
2  2015                1
3  2018              140

New DataFrame:
   year  day_of_the_year  combined       date
0  2002              250   2002250 2002-09-07
1  2003              365   2003365 2003-12-31
2  2015                1   2015001 2015-01-01
3  2018              140   2018140 2018-05-20

For more Practice: Solve these Related Problems:

Write a Pandas program to merge separate 'year' and 'day-of-year' columns into a single datetime column and handle leap years.
Write a Pandas program to convert integer year and day-of-year values into datetime and then sort the DataFrame by the new column.
Write a Pandas program to create a DataFrame with year and day-of-year, convert it to datetime, and then filter for a specific month.
Write a Pandas program to generate a datetime index from year and day-of-year columns and verify the resulting format.

Go to:

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Next: Write a Pandas program to create a series of Timestamps from a DataFrame of integer or string columns. Also create a series of Timestamps using specified columns.

Python Code Editor:

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