问题
2012-10-08 07:12:22 0.0 0 0 2315.6 0 0.0 0
2012-10-08 09:14:00 2306.4 20 326586240 2306.4 472 2306.8 4
2012-10-08 09:15:00 2306.8 34 249805440 2306.8 361 2308.0 26
2012-10-08 09:15:01 2308.0 1 53309040 2307.4 77 2308.6 9
2012-10-08 09:15:01.500000 2308.2 1 124630140 2307.0 180 2308.4 1
2012-10-08 09:15:02 2307.0 5 85846260 2308.2 124 2308.0 9
2012-10-08 09:15:02.500000 2307.0 3 128073540 2307.0 185 2307.6 11
......
2012-10-09 07:19:30 0.0 0 0 2276.6 0 0.0 0
2012-10-09 09:14:00 2283.2 80 98634240 2283.2 144 2283.4 1
2012-10-09 09:15:00 2285.2 18 126814260 2285.2 185 2285.6 3
2012-10-09 09:15:01 2285.8 6 98719560 2286.8 144 2287.0 25
2012-10-09 09:15:01.500000 2287.0 36 144759420 2288.8 211 2289.0 4
2012-10-09 09:15:02 2287.4 6 109829280 2287.4 160 2288.6 5
......
I have a DataFrame contains several days of exchange trading data as above. The the data I want to have is from 9:00:00AM - 11:30:00AM and 13:00:00 - 15:15:00, so I would like to do two things,
- for each date in the DataFrame truncate to only have data in the
range of
9:00:00AM - 11:30:00AMand13:00:00 - 15:15:00 - with the range in 1., fill missing data with a frequency of
500 milliseconds
the pandas truncate functions only allows me to truncate according to date, but I would like to truncate according to datetime.time here. Also how to fill the missing data only for the interval I am interested.
Thanks a lot.
回答1:
- for each date in the DataFrame truncate to only have data in the range of 9:00:00AM - 11:30:00AM and 13:00:00 - 15:15:00
Use index slicing for that, e.g.:
df = df[start_timestamp:end_timestamp]
- with the range in 1., fill missing data with a frequency of 500 milliseconds
Generate a new dataframe with an index at 500 msec. Merge this dataframe with the original one using outer join. This gets you a dataframe with rows at regular intervals. Rows for missing observations will contain NaN values. Then fill missing NaN values with fillna.
Example:
In [1]: import pandas as pd
In [2]: import numpy as np
In [3]: data = pd.DataFrame({"value": np.arange(5)}, index=pd.date_range("2013/02/03", periods=5, freq="3Min"))
In [4]: data
Out[4]:
value
2013-02-03 00:00:00 0
2013-02-03 00:03:00 1
2013-02-03 00:06:00 2
2013-02-03 00:09:00 3
2013-02-03 00:12:00 4
In [5]: filler = pd.DataFrame({"value": [100] * 15}, index=pd.date_range("2013/02/03", periods=15, freq="1Min"))
In [6]: filler
Out[6]:
value
2013-02-03 00:00:00 100
2013-02-03 00:01:00 100
2013-02-03 00:02:00 100
2013-02-03 00:03:00 100
2013-02-03 00:04:00 100
2013-02-03 00:05:00 100
2013-02-03 00:06:00 100
2013-02-03 00:07:00 100
2013-02-03 00:08:00 100
2013-02-03 00:09:00 100
2013-02-03 00:10:00 100
2013-02-03 00:11:00 100
2013-02-03 00:12:00 100
2013-02-03 00:13:00 100
2013-02-03 00:14:00 100
In [7]: merged = filler.merge(data, how='left', left_index=True, right_index=True)
In [8]: merged["value"] = np.where(np.isfinite(merged.value_y), merged.value_y, merged.value_x)
In [9]: merged
Out[9]:
value_x value_y value
2013-02-03 00:00:00 100 0 0
2013-02-03 00:01:00 100 NaN 100
2013-02-03 00:02:00 100 NaN 100
2013-02-03 00:03:00 100 1 1
2013-02-03 00:04:00 100 NaN 100
2013-02-03 00:05:00 100 NaN 100
2013-02-03 00:06:00 100 2 2
2013-02-03 00:07:00 100 NaN 100
2013-02-03 00:08:00 100 NaN 100
2013-02-03 00:09:00 100 3 3
2013-02-03 00:10:00 100 NaN 100
2013-02-03 00:11:00 100 NaN 100
2013-02-03 00:12:00 100 4 4
2013-02-03 00:13:00 100 NaN 100
2013-02-03 00:14:00 100 NaN 100
In [10]: merged['2013-02-03 00:01:00':'2013-02-03 00:10:00']
Out[10]:
value_x value_y value
2013-02-03 00:01:00 100 NaN 100
2013-02-03 00:02:00 100 NaN 100
2013-02-03 00:03:00 100 1 1
2013-02-03 00:04:00 100 NaN 100
2013-02-03 00:05:00 100 NaN 100
2013-02-03 00:06:00 100 2 2
2013-02-03 00:07:00 100 NaN 100
2013-02-03 00:08:00 100 NaN 100
2013-02-03 00:09:00 100 3 3
2013-02-03 00:10:00 100 NaN 100
来源：https://stackoverflow.com/questions/14671345/python-pandas-how-to-truncate-datetimeindex-and-fill-missing-data-only-in-certa