问题
I have pandas Dataframe with datetime index like 'YYYY-MM-DD HH:MM:SS'.
Index Parameter
2007-05-02 14:14:08 134.8
2007-05-02 14:14:32 134.8
2007-05-02 14:14:41 134.8
2007-05-02 14:14:53 134.8
2007-05-02 14:15:01 134.8
2007-05-02 14:15:09 134.8
......
2007-05-30 23:08:02 105.9
2007-05-30 23:18:02 105.9
2007-05-30 23:28:02 105.9
2007-05-30 23:38:03 105.8
It is possible to get slice a DataFrame by year df['2007'] or by month df['2007-05']?
But when I've tried to slice DataFrame by day, for example df['2007-05-02'], I've got the error:
KeyError: < Timestamp: 2007-02-05 00:00:00.
I use the pandas version 8.0.1. Is it possible to slice DataFrame with smaller frequency than year or month? For example, by day or hour?
回答1:
use df.ix[x:y] where x and y are datetime objects.
Example:
In [117]: frame.index.summary()
Out[117]: 'DatetimeIndex: 6312960 entries, 2000-04-05 00:01:00 to 2012-04-06 00:00:00\nFreq: T'
In [118]: x=datetime(2001, 4, 5, 0, 1)
In [119]: y=datetime(2001, 4, 5, 0, 5)
In [120]: print frame.ix[x:y]
radiation tamb
2001-04-05 00:01:00 67.958873 8.077386
2001-04-05 00:02:00 50.801294 0.731453
2001-04-05 00:03:00 16.042035 6.944998
2001-04-05 00:04:00 5.678343 9.728967
2001-04-05 00:05:00 72.551601 7.652942
you can also do this:
In [121]: print frame.ix[x]
radiation 67.958873
tamb 8.077386
Name: 2001-04-05 00:01:00
来源：https://stackoverflow.com/questions/12910187/pandas-dataframe-slicing-by-day-hour-minute