Python Pandas ValueError: cannot reindex from a duplicate axis

Question

This might be really simple but I'm trying to get a subset of values from a dataframe by selecting values where a column meets a specific value. So this:

test_df[test_df.ProductID == 18]

But I'm getting this error: *** ValueError: cannot reindex from a duplicate axis

Which is weird cause when I run this:

test_df.index.is_unique

I get true since my indices are unique. So what am I doing wrong?

I was able to get the exact same thing to work with another column:

test_df[test_df.AttributeID == 1111]

and that works exactly as expected.

Solved. I didn't check my dataframe close enough, there were duplicate columns called ProductID and that was what was causing the error.

Answer 1

If something is wrong with your index, you might reset the index with:

test_df.reset_index(level=0, inplace=True)