There is a df Pandas dataframe: date av_temp deviations country 1 1743-12-01 NaN NaN Åland 2 1744-01-01 NaN NaN Åland 3 1744-02-01 NaN NaN Åland 4 1744-03-01 NaN NaN Åland 9 1744-08-01 NaN NaN Åland Create a new column year from date in which you convert all date values to years. Example: 1744-01-01 Date column: 1744

def get_year(date):
    return int(date[:4])

def get_month(date):
    return int(date[5:7])

def get_day(date):
    return int(date[8:])

df['year'] = df['date'].apply(get_year)
df['month'] = df['date'].apply(get_month)
df['day'] = df['date'].apply(get_day)