上一年和下一年的天数- pandas [英] no of days to previous and next year - Pandas

问题描述

我有一个如下所示的数据帧

I have a data frame like as shown below

df1 = pd.DataFrame({'person_id': [11, 21, 31, 41, 51],
                        'date_1': ['12/30/1961', '05/29/1967', '02/03/1957', '7/27/1959', '01/13/1971'],
                        'date_2': ['07/23/2017','05/29/2017','02/03/2015',np.nan,np.nan]})
df1 = df1.melt('person_id', value_name='dates')

我想获得到上一年和明年的天数。

我能够获得前一天和明年明年使用以下代码

df1['cur_year'] = pd.DatetimeIndex(df1['dates']).year
df1['prev_year'] = (df1['cur_year'] - 1)
df1['next_year'] = (df1['cur_year'] + 1)

您可以看到 year 的值在不断变化每行，而且我没有固定的基准日期，如何计算与 31/12 前一年， 01/01 次年。

As you can see that the year values are constantly changing for each row and I don't have a fixed baseline date, how can I calculate the difference in days to dates like 31/12 for the previous year and 01/01 for the next year.

请注意，获取天数时不包括结束日期

Please note that end date is not included while getting the number of days

我已经显示了示例输出以下2个科目。

I have shown a sample output for 2 subjects below.

更新的屏幕截图

推荐答案

据我了解，您可以尝试；

From what i understand, you can try;

df1['dates'] = pd.to_datetime(df1['dates'])
out = df1.assign(prev_yr_days=df1['dates'].dt.dayofyear,
     next_yr_days=((df1['dates'] + pd.offsets.YearEnd(0)) - df1['dates']).dt.days.add(1))

---

---

   person_id variable      dates  prev_yr_days  next_yr_days
0         11   date_1 1961-12-30         364.0           2.0
5         11   date_2 2017-07-23         204.0         162.0
1         21   date_1 1967-05-29         149.0         217.0
6         21   date_2 2017-05-29         149.0         217.0
2         31   date_1 1957-02-03          34.0         332.0
7         31   date_2 2015-02-03          34.0         332.0
3         41   date_1 1959-07-27         208.0         158.0
8         41   date_2        NaT           NaN           NaN
4         51   date_1 1971-01-13          13.0         353.0
9         51   date_2        NaT           NaN           NaN

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