如何在python中保留相应的列？

Question

我按季节划分日期，但我需要在单独的部分中保留相应的列。打印的数据看起来像

index       time  DayNum
0     1979-01-01     3.0
1     1979-01-02     3.0
2     1979-01-03     5.0
3     1979-01-04     2.0
4     1979-01-05     2.0
5     1979-01-06     6.0
(this continue for 30 years)

其中时间是事件的日期，DayNum是当天发生的数字。我现在尝试按季节将其分开，然后保留与之对应的DayNum列。 目前，我正在使用熊猫。为了得到上面的图表，我做了：

import numpy as np
import pandas as pd

daycoun = 37*365 + 9
yearday = np.zeros(daycoun, pd.Timestamp)
daycount = np.zeros(daycoun) # 9 is number of leap years
for i in range(daycoun):
    test = np.where((dq.iloc[:] >= D1D + pd.Timedelta(days = i)) & (dq.iloc[:] < D1D + pd.Timedelta(days = i+1)))
    daycount[i] = len(dq.iloc[test])
    yearday[i] = (D1D + pd.Timedelta(days = i))
yd = pd.DataFrame({'time':yearday, 'DayNum':daycount})`

请询问您是否需要澄清