[英]pandas: how to extract a set of dates from a DataFrame with datetime index?
I have two DataFrames with TimesSeriesIndex, df1, df2. 我有两个带有TimesSeriesIndex,df1,df2的数据框。
df2's index is a subset of df1.index. df2的索引是df1.index的子集。
How can I extract the index dates from df1 which also contained by df2, so I can run analysis on these dates. 我如何从df2中也包含的df1中提取索引日期,以便可以对这些日期进行分析。
Take the intersection of their indices. 取其索引的交集。
In [1]: import pandas as pd In [2]: index1 = pd.DatetimeIndex(start='2000-1-1', freq='1T', periods=1000000) In [3]: index2 = pd.DatetimeIndex(start='2000-1-1', freq='1D', periods=1000) In [4]: index1 Out[4]: [2000-01-01 00:00:00, ..., 2001-11-25 10:39:00] Length: 1000000, Freq: T, Timezone: None In [5]: index2 Out[5]: [2000-01-01 00:00:00, ..., 2002-09-26 00:00:00] Length: 1000, Freq: D, Timezone: None In [6]: index1 & index2 Out[6]: [2000-01-01 00:00:00, ..., 2001-11-25 00:00:00] Length: 695, Freq: D, Timezone: None
In your case, do the following: 对于您的情况,请执行以下操作:
index1 = df1.index index2 = df2.index
Then take the intersection of these as defined before. 然后按照前面的定义进行交叉。 Later you may wish to do something like the following to get the df
at intersection index. 稍后,您可能希望执行以下操作来获得交点索引处的df
。
df1_intersection =df1.ix[index1 & index2]
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