检索pandas数据帧中的.loc索引值

Question

I have a dataframe which uses the date column of each row as a .loc index. See below

>>> aapl.head()
             Open   High    Low  Close    Volume  Adj Close
Date                                                       
1980-12-12  28.75  28.88  28.75  28.75  16751200       3.15
1980-12-15  27.38  27.38  27.25  27.25   6281600       2.99
1980-12-16  25.38  25.38  25.25  25.25   3776000       2.77
1980-12-17  25.88  26.00  25.88  25.88   3087200       2.84
1980-12-18  26.62  26.75  26.62  26.62   2623200       2.92

[5 rows x 6 columns]

I am trying to retrieve the date of the first row, however (I assume it's because date is used as the index), the good ol' date=aapl.iloc[0]['Date'] doesn't work...though it does work for any other column.

My question is, specifically, how can I retrieve the date value for the first row? That is to say, in general terms, how do I retrieve the .loc index of the first row of a dataframe?

Thanks in advance; help much appreciated.

Answer 1

You need to access the index of the data frame, not the columns. To do this you can do the following:

DF.index[x]

So in your case:

appl.index[0]

Incidentally if you want to get 'Date' out of the index, so you can reference it in the way you are accustomed to (ie as a column) you can reset the index:

appl.reset_index(inplace = True)

And then if you decide you don't like that you can just change it back:

appl.set_index('Date', inplace = True)