d = {1:0, 2:0, 3:1, 4:0, 5:2, 6:1, 7:2, 8:0}

pandas_ordered = { 0:[1,2,4,8], 1:[3,6], 2:[5,7] }

pd.Series(list(d.values())).groupby(list(partition.keys())).to_dict()

# Example:
import pandas as pd

d = {1:0, 2:0, 3:1, 4:0, 5:2, 6:1, 7:2, 8:0}


def pandas_groupby(dictionary):
   values = list(dictionary.values())
   keys = list(dictionary.keys())
   return pd.Series(values).groupby(keys).to_dict()


pandas_groupby(d)