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values = set(map(lambda x:x[1], mylist))
newlist = [[y[0] for y in mylist if y[1]==x] for x in values]
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#calculate sum of sales grouped by month
df.groupby(df.date.dt.month)['sales'].sum()
date
1 34
2 44
3 31
Name: sales, dtype: int64
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# car_sales:> it is dataframe
# "Make" is column, or feature name
# operation is mean
car_sales.groupby(["Make"]).mean()