比较python数据框中的日期范围

Question

I am having a daterange in pandas.core.indexes.datetimes.DatetimeIndexDatetimeIndex as :

(['2021-03-21', '2021-03-22', '2021-03-23', '2021-03-24',
               '2021-03-25', '2021-03-26', '2021-03-27', '2021-03-28',
               '2021-03-29', '2021-03-30', '2021-03-31', '2021-04-01',
               '2021-04-02', '2021-04-03', '2021-04-04'],
              dtype='datetime64[ns]', freq='D')

Moreover series data as:

2021-03-27    2
2021-03-28    1
2021-03-30    1
2021-03-31    2
2021-04-04    3

Now if I want to get a dataframe with all dates and its opposite value as it is and if any date is missing it should give answer as that date as 0 value. Output format should be:

2021-03-22    0
2021-03-23    0
2021-03-24    0
2021-03-25    0
2021-03-26    0
2021-03-27    2
2021-03-28    1
...

Answer 1

IIUC use Series.reindex , only necessary DatetimeIndex in Series for matching idx :

idx = pd.DatetimeIndex(['2021-03-21', '2021-03-22', '2021-03-23', '2021-03-24',
                       '2021-03-25', '2021-03-26', '2021-03-27', '2021-03-28',
                       '2021-03-29', '2021-03-30', '2021-03-31', '2021-04-01',
                       '2021-04-02', '2021-04-03', '2021-04-04'])


print (s)
2021-03-27    2
2021-03-28    1
2021-03-30    1
2021-03-31    2
2021-04-04    3
Name: a, dtype: int64

---

s.index = pd.to_datetime(s.index)
s = s.reindex(idx, fill_value=0)
print (s)
2021-03-21    0
2021-03-22    0
2021-03-23    0
2021-03-24    0
2021-03-25    0
2021-03-26    0
2021-03-27    2
2021-03-28    1
2021-03-29    0
2021-03-30    1
2021-03-31    2
2021-04-01    0
2021-04-02    0
2021-04-03    0
2021-04-04    3
Name: a, dtype: int64

If want reindex by date_range instead idx use it:

s = s.reindex(pd.date_range('2021-03-21', '2021-04-04', freq='D'), fill_value=0)