नेस्टेड कैटेगरी बनाना

melb["month"] = melb["date"].dt.month
quarters = {1: "Q1", 2:"Q1", 3:"Q1", 4:"Q2", 5:"Q2", 6:"Q2", 7:"Q3", 8:"Q3", 9:"Q3", 10:"Q4", 11:"Q4", 12:"Q4"}
melb["quarter"] = melb["month"].replace(quarters)
melb["month"] = melb["month"].replace({1:"January", 2:"February", 3:"March", 4:"April", 5:"May", 6:"June", 7:"July", 8:"August", 9:"September", 10:"October", 11:"November", 12:"December"})

# Create factors
factors = [("Q1", "January"), ("____", "February"), ("____", "March"), 
           ("Q2", "April"), ("____", "____"), ("____", "____"), 
           ("Q3", "July"), ("____", "____"), ("____", "____"), 
           ("Q4", "October"), ("____", "____"), ("____", "____")]

# Calculate total sales by month and quarter
grouped_melb = melb.groupby(["____", "____"], as_index=False)["____"].sum()
grouped_melb.sort_values("quarter", inplace=True)
print(grouped_melb.head())