ValueError: DataFrame index must be unique for orient='columns'

Question

I merged many dataframes into bigger one,

pd.concat(dfs, axis=0)

then I can not dump it into json

(Pdb) df.to_json() *** ValueError: DataFrame index must be unique for orient='columns'. 

How could I fix it ?

Answer 1

The error indicates that your dataframe index has non-unique (repeated) values. Since it appears you're not using the index, you could create a new one with:

df.reset_index(inplace=True) 

or

df.reset_index(drop=True, inplace=True) 

if you want to remove the previous index.

Check this link as well.