Sorting based on string type. Problems when distance is very small value ('5.55555E-6')

[JoanFM]

We have observed some weird behavior seeing small distances at the end of the list of closest matches.

I believe the problem is that the distances are returned as string types and then the sorting does not work

pysparnn/pysparnn/cluster_index.py

Line 26 in c299c82

tuple_lst = sorted(tuple_list, key=lambda x: x[0],

[JoanFM]

Problem appears when keys indexed are of type str