Concat DataFrame Reindexing only valid with uniquely valued Index objects

Question

I am trying to concat the following:

df1

    price   side    timestamp
timestamp           
2016-01-04 00:01:15.631331072   0.7286  2   1451865675631         


        

Answer 1

best solution from this page: https://pandas.pydata.org/pandas-docs/version/0.20/merging.html

df = pd.concat([df1, df2], axis=1, join_axes=[df1.index])