Creating Datetime In Pandas From Year And Julian Day

ad_name adl_name year JD 0 united_states_of_america colorado 2000 1 1 united_states_of_america colorado 2000 2 2 united_states_of_america colo

Solution 1:

You need add to year column JD converted to_timedelta:

df['date']=pd.to_datetime(df.year,format='%Y')+pd.to_timedelta(df.JD-1,unit='d')print(df)ad_nameadl_nameyearJDdate0united_states_of_americacolorado2000   12000-01-011united_states_of_americacolorado2000   22000-01-022united_states_of_americacolorado2000   32000-01-033united_states_of_americacolorado2000   42000-01-044united_states_of_americacolorado2000   52000-01-05

Sample with JD=32 and JD=366:

print (df)
                    ad_name  adl_name  year   JD
0  united_states_of_america  colorado  2000   32
1  united_states_of_america  colorado  2000  366

df['date'] = pd.to_datetime(df.year, format='%Y') + pd.to_timedelta(df.JD - 1, unit='d')
print (df)
                    ad_name  adl_name  year   JD       date
0  united_states_of_america  colorado  2000   32 2000-02-01
1  united_states_of_america  colorado  2000  366 2000-12-31