如果有生日专栏，如何计算一个人当天的年龄？

Question

firstname,secondname,birthdate
vanco,grizov,3-16-1983
vlado,stojanov,6-24-1982
goce,grizov,7-18-1985

import pandas as pd
from datetime import date

data=pd.read_csv(r'C:\\Users\\User\\Desktop\\test\\vanco.csv')
data.head(3)
print(data)

data.birthdate=pd.to_datetime(data.birthdate)
data.head(3)
print (data)

def calculate_age(born):
    today = date.today()
    return today.year - born.year - ((today.month, today.day) < (born.month, born.day))


data['birthdate'].apply(lambda x: calculate_age(x))
print(data)

根据一段代码，我在PyCharm中有这个输出

我编写代码，然后将csv文件中的列birthdate转换为datetime对象：

然后我编写一个函数来创建并返回出生日期的年龄

def calculate_age(born):
    today = date.today()
    return today.year - born.year - ((today.month, today.day) < (born.month, born.day))

data['birthdate'].apply(lambda x: calculate_age(x))
print(data)

从代码中，我在PyCharm控制台中有这个输出

filename secondname  birthdate
0    vanco     grizov  3-16-1983
1    vlado   stojanov  6-24-1982
2     goce     grizov  7-18-1985
  filename secondname  birthdate
0    vanco     grizov 1983-03-16
1    vlado   stojanov 1982-06-24
2     goce     grizov 1985-07-18
  filename secondname  birthdate
0    vanco     grizov 1983-03-16
1    vlado   stojanov 1982-06-24
2     goce     grizov 1985-07-18

• 预期的输出是一个带有年龄的列，应该添加到数据帧中

Answer 1

• 这个答案假设期望的输出是年龄，以年为单位，从生日到今天。
• （今天-bd）返回总天数的值。
  • 除以pd. timedelta（天=365.25），得到年数。
    • 365.25因为一年的长度变化

    import pandas as pd
    from datetime import date
    
    # read the file in and covert the birthdate column to a datetime
    df = pd.read_csv('vanco.csv', parse_dates=['birthdate'])
    
    # function
    def calc_age(bd: pd.Series) -> pd.Series:
        today = pd.to_datetime(date.today())  # convert today to a pandas datetime
        return (today - bd) / pd.Timedelta(days=365.25)  # divide by days to get years
    
    
    # call function and assign the values to a new column in the dataframe
    df['age (years)'] = calc_age(df.birthdate)
    
    # display(df)
      firstname secondname  birthdate  age (years)
    0     vanco     grizov 1983-03-16     37.48118
    1     vlado   stojanov 1982-06-24     38.20671
    2      goce     grizov 1985-07-18     35.14031
    

    • 使用dateutil模块，该模块有更多功能丰富的方法选择
      • relativedelta将补偿闰年
      • 使用。年份从relativedelta对象中仅提取年份组件

      # updated function with relativedelta
      def calc_age(bd: pd.Series):
          today = pd.to_datetime(date.today())
          return bd.apply(lambda x: relativedelta(today, x).years)
      
      
      # function call
      df['age (years)'] = calc_age(df.birthdate)
      
      # display(df)
        firstname secondname  birthdate  age (years)
      0     vanco     grizov 1983-03-16           37
      1     vlado   stojanov 1982-06-24           38
      2      goce     grizov 1985-07-18           35
      
      # the output if .years is removed from the calc_age function
        firstname secondname  birthdate                                    age (years)
      0     vanco     grizov 1983-03-16  relativedelta(years=+37, months=+5, days=+22)
      1     vlado   stojanov 1982-06-24  relativedelta(years=+38, months=+2, days=+14)
      2      goce     grizov 1985-07-18  relativedelta(years=+35, months=+1, days=+20)