如何连接列

Question

I have download two data frames, that I want to concat them together (I am not programmer). I am using Python 2.7.

My code is like this:

from pandas_datareader.data import Options
import datetime
import pandas as pd

pd.set_option('display.width',280) # default is 80

aapl = Options('aapl', 'yahoo')
expiry = datetime.date(2017, 1, 1)

data_CALL = aapl.get_call_data(expiry=expiry)
data_PUT = aapl.get_put_data(expiry=expiry)

#The first DataFrame
Q1=data_CALL.iloc[0:5, 0:8]
print(Q1.head())

#The Second DataFrame
Q2=data_PUT.iloc[0:5:, 0:8]
print(Q2.head())


#I got this DataFrame
concat=pd.concat([Q1,Q2])
print(concat)

The results looks like:

I want that my final data frame look like this:

Answer 1

your result looks like a result of using groupby object. ie you have grouped your data by strike as your grouping attribute.

to do it this way, you need to remove your composite index for each dataframe; from the look of it you have a index of (Strik, Expiry, Type, Symbol) .

I can only assume this is set up in your get_call_data and get_put_data functions as they return dataframes directly. I would suggest that you import raw dataframe as is without setting any index, at this moment; this way strike will remain as column which you could easily use as your grouping attribute as shown below.

actually grouping is very easy:

combined = pd.concat([Q1, Q2])
grouped = combined.groupby('strike')  # single grouping attribute

to validate result:

for name, group in grouped:
    print name
    print group

to manipulate the data (just a few examples here):

# 1. using groupby builtin functions

first_group = grouped.first()  # you can do last()
first_strike = grouped.get_group('115')  # return you a dataframe as given by you

# 2. using list

group_list = list(grouped)
first_group = group_list[0]  # return a tuple with 2 elements: name and DataFrame
first_strike_name = group_list[0][0]
first_strike_data = group_list[0][1]

you can read more about Python GroupBy here .

Answer 2

As per your description you have two dataframes Q1 and Q2 and you wanted to concatenate both on "Strike" index . For the same code will be something like these ,

Concetenateddf=pd.concat([Q1.set_index('Strike'),Q2.set_index('Strike')], axis=1, join='inner')

Now if you will do Concetenateddf.head() then you will get similar results as you are expecting .