创建 DataFrame 后设置 Pandas DatetimeIndex 的频率
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Setting freq of pandas DatetimeIndex after DataFrame creation
提问by user3139545
Im using pandas datareader to get stock data.
我使用Pandas数据阅读器来获取股票数据。
import pandas as pd
import pandas_datareader.data as web
ABB = web.DataReader(name='ABB.ST',
data_source='yahoo',
start='2000-1-1')
However by default freq is not set on the resulting dataframe. I need freq to be able to navigate using the index like this:
但是，默认情况下，不会在结果数据帧上设置 freq。我需要 freq 才能使用这样的索引进行导航：
for index, row in ABB.iterrows():
ABB.loc[[index + 1]]
If freq is not set on DatetimeIndex im not able to use +1etc to navigate.
如果未在 DatetimeIndex 上设置 freq，我将无法使用+1等进行导航。
What I have found are two functions astypeand resample. Since I already know to freq resamplelooks like overkill, I just want to set freq to daily.
我发现的是两个函数astype和resample. 由于我已经知道 freqresample看起来有点矫枉过正，我只想将 freq 设置为每天。
Now my question is how can i use astype on ABB to set freq to daily?
现在我的问题是如何在 ABB 上使用 astype 将频率设置为每天？
采纳答案by Abdou
Try:
尝试：
ABB = ABB.asfreq('d')
This should change the frequency to daily with NaNfor days without data.
这应该在NaN没有数据的情况下将频率更改为每天。
Also, you should rewrite your for-loopas follows:
此外，你应该重写你for-loop的如下：
for index, row in ABB.iterrows():
print(ABB.loc[[index + pd.Timedelta(days = 1)]])
Thanks!
谢谢！
回答by Rohit Nandi
ABB is pandas DataFrame, whose indextype is DatetimeIndex.
ABB 是 pandas DataFrame，其索引类型为DatetimeIndex。
DatetimeIndexhas freqattribute which can be set as below
DatetimeIndex具有freq属性，可以设置如下
ABB.index.freq = 'd'
Check out the change
看看变化
ABB.index
回答by jezrael
If need change frequency of index resampleis for you, but then need aggregate columns by some functions like meanor sum:
如果需要更改索引的频率resample适合您，但需要通过某些函数（如mean或）聚合列sum：
print (ABB.resample('d').mean())
print (ABB.resample('d').sum())
If need select another row use ilocwith get_locfor find position of value in DatetimeIndex:
如果需要选择其他行使用iloc与get_loc用于在价值发现的位置DatetimeIndex：
print (ABB.iloc[ABB.index.get_loc('2001-05-09') + 1])
Open 188.00
High 192.00
Low 187.00
Close 191.00
Volume 764200.00
Adj Close 184.31
Name: 2001-05-10 00:00:00, dtype: float64
