In order to preserve your index after the aggregation, you need to make sure it is considered a data column (via reset_index) and then choose how your aggregation will operate on that column.
On Fri, May 13, 2016 at 3:29 PM David Shi <davidg...@yahoo.co.uk> wrote: > Hello, Michael, > > Why reset_index before grouping? > > Regards. > > David > > > On Friday, 13 May 2016, 17:57, Michael Selik <michael.se...@gmail.com> > wrote: > > > > > On Fri, May 13, 2016 at 12:27 PM David Shi via Python-list < > python-list@python.org> wrote: > > I lost my indexes after grouping in Pandas. > I managed to rest_index and got back the index column. > But How can I get back a index row? > > > Was the grouping an aggregation? If so, the original indexes are > meaningless. What you could do is reset_index before the grouping and when > you aggregate decide how to handle the formerly-known-as-index column (min, > max, mean, ?). > > > -- https://mail.python.org/mailman/listinfo/python-list
