Inserting a python list into a dataframe column wise

Question

I have the following python list,

test_list = 
[ ['CVM', 20010618, 332.5],
['CVM', 20010619, 332.5],
['CVM', 20010620, 330.0],
['CVM', 20010621, 342.5],
['CVM', 20010622, 337.5],
['AEF', 19970102, 18.7489],
['AEF', 19970103, 18.9735],
['AEF', 19970106, 19.5348],
['AEF', 19970107, 19.6471] ]

I want to concat it into a dataframe with axis=1, so it would be like that in the dataframe

<TICKER><DTYYYYMMDD><CLOSE><TICKER><DTYYYYMMDD><CLOSE>
'CVM'     20010619   332.5  'AEF'    19970102   18.7489
'CVM'     20010620   330.0  'AEF'    19970103   18.9735
'CVM'     20010621   342.5  'AEF'    19970106   19.5348
'CVM'     20010622   337.5  'AEF'    19970107   19.6471

I used the following code:

frame = pd.concat(test_list, axis=1, ignore_index=True)

but I get the following error

TypeError: cannot concatenate object of type < class 'list' >
    only pd.Series, pd.DataFrame, and pd.Panel (deprecated) objs are valid

BENY · Accepted Answer · 2019-03-04 23:46:51Z

2

First you convert to one dataframe , then groupby the ticker columns , then we do concat

pd.concat([y.reset_index(drop=True) for _, y in pd.DataFrame(test_list).groupby(0)],axis=1)
Out[351]: 
     0           1        2    0         1      2
0  AEF  19970102.0  18.7489  CVM  20010618  332.5
1  AEF  19970103.0  18.9735  CVM  20010619  332.5
2  AEF  19970106.0  19.5348  CVM  20010620  330.0
3  AEF  19970107.0  19.6471  CVM  20010621  342.5
4  NaN         NaN      NaN  CVM  20010622  337.5

answered Mar 4, 2019 at 23:46

BENY

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