查找给定日期,熊猫的季度结束日期

Question

假设我们有一个像这样的表

table = [[datetime.datetime(2015, 1, 1), 1, 0.5],
         [datetime.datetime(2015, 1, 27), 1, 0.5],
         [datetime.datetime(2015, 1, 31), 1, 0.5],
         [datetime.datetime(2015, 2, 1), 1, 2],
         [datetime.datetime(2015, 2, 3), 1, 2],
         [datetime.datetime(2015, 2, 15), 1, 2],
         [datetime.datetime(2015, 2, 28), 1, 2],
         [datetime.datetime(2015, 3, 1), 1, 3],
         [datetime.datetime(2015, 3, 17), 1, 3],
         [datetime.datetime(2015, 3, 31), 1, 3]]

df = pd.DataFrame(table, columns=['Date', 'Id', 'Value'])

有没有办法在列中的日期给出实际季度的具体结束日期Date？例如,我想将列添加Q_date到df这样

        Date  Id  Value  Qdate
0 2015-01-01   1    0.5  2015-03-31
1 2015-01-27   1    0.5  2015-03-31
2 2015-01-31   1    0.5  2015-03-31
3 2015-02-01   1    2.0  2015-03-31
4 2015-02-03   1    2.0  2015-03-31
5 2015-02-15   1    2.0  2015-03-31
6 2015-02-28   1    2.0  2015-03-31
7 2015-03-01   1    3.0  2015-03-31
8 2015-03-17   1    3.0  2015-03-31
9 2015-03-31   1    3.0  2015-03-31

我只考虑了第一季的简单性 - 因为我知道它是什么日期.

Answer 1

您可以pd.tseries.offsets.QuarterEnd()在此处实现目标.

import pandas as pd
import datetime

# your data
# ================================
table = [[datetime.datetime(2015, 1, 1), 1, 0.5],
         [datetime.datetime(2015, 1, 27), 1, 0.5],
         [datetime.datetime(2015, 1, 31), 1, 0.5],
         [datetime.datetime(2015, 2, 1), 1, 2],
         [datetime.datetime(2015, 2, 3), 1, 2],
         [datetime.datetime(2015, 2, 15), 1, 2],
         [datetime.datetime(2015, 2, 28), 1, 2],
         [datetime.datetime(2015, 3, 1), 1, 3],
         [datetime.datetime(2015, 3, 17), 1, 3],
         [datetime.datetime(2015, 3, 31), 1, 3]]

df = pd.DataFrame(table, columns=['Date', 'Id', 'Value'])

# processing
# ================================
# in case of 2015.03.31, simple QuarterEnd will roll forward to next quarter, so use DateOffset here to make it robust to this
df['Qdate'] = [date - pd.tseries.offsets.DateOffset(days=1) + pd.tseries.offsets.QuarterEnd() for date in  df.Date]

print(df)


        Date  Id  Value      Qdate
0 2015-01-01   1    0.5 2015-03-31
1 2015-01-27   1    0.5 2015-03-31
2 2015-01-31   1    0.5 2015-03-31
3 2015-02-01   1    2.0 2015-03-31
4 2015-02-03   1    2.0 2015-03-31
5 2015-02-15   1    2.0 2015-03-31
6 2015-02-28   1    2.0 2015-03-31
7 2015-03-01   1    3.0 2015-03-31
8 2015-03-17   1    3.0 2015-03-31
9 2015-03-31   1    3.0 2015-03-31

Answer 2

一种更简单的方法是将日期转换为（季度）期间，然后再转换回日期，例如：

df['Qdate'] = df['Date'].dt.to_period("Q").dt.end_time

请注意.start_time，该季度的开始也是如此。