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

Another thing that might throw this type of errors is when you have a column with a unique value inside (entropy of 0). In this case, you can either inject small Gaussian noise in that column or remove it completely.