Fix for new Pandas API (#7975)

superset/viz.py

@@ -42,6 +42,7 @@ from markdown import markdown
 import numpy as np
 import pandas as pd
 from pandas.tseries.frequencies import to_offset
+from pandas.tseries.offsets import DateOffset
 import polyline
 import simplejson as json
 
@@ -1398,7 +1399,8 @@ class NVD3TimePivotViz(NVD3TimeSeriesViz):
         fd = self.form_data
         df = self.process_data(df)
         freq = to_offset(fd.get("freq"))
-        freq.normalize = True
+        freq = DateOffset(normalize=True, **freq.kwds)
+        df.index.name = None
         df[DTTM_ALIAS] = df.index.map(freq.rollback)
         df["ranked"] = df[DTTM_ALIAS].rank(method="dense", ascending=False) - 1
         df.ranked = df.ranked.map(int)