Omid - Challenge 163

data-challenges
advanced-exercises
🔰 Custom Grouping!
Published

March 24, 2026

Illustration for Omid - Challenge 163

Challenge Description

🔰 Custom Grouping!

Solutions

library(tidyverse)
library(readxl)

path = "files/CH-163 Custom Grouping.xlsx"
input = read_excel(path, range = "B2:D39")
test  = read_excel(path, range = "G2:I17")

result = input %>% 
  unite("ym", Year, Month ,  sep = " ", remove = F) %>%
  mutate(ym = ym(ym),
         Season = quarter(ym)) %>%
  summarise(`Total Sale` = sum(Sale), .by = c(Year, Season))

all.equal(result, test)
# TRUE

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Aggregates or ranks values at the relevant grouping level

    • Builds the intermediate columns that drive the final result

  • Strengths:

    • The R solution stays close to the workbook rule and keeps the transformation compact.

  • Areas for Improvement:

    • The code assumes the sheet structure and source ranges remain stable.

  • Gem:

    • The strongest part of the solution is choosing the right intermediate representation before shaping the final output.
import pandas as pd

path = "CH-163 Custom Grouping.xlsx"
input = pd.read_excel(path, usecols="B:D", skiprows=1, nrows=38)
test = pd.read_excel(path, usecols="G:I", skiprows=1, nrows=15)

input['Season'] = pd.to_datetime(input['Year'].astype(str) + " " + input['Month'], format='%Y %b').dt.quarter

result = input.groupby(['Year', 'Season'])['Sale'].sum().reset_index()
result.columns = test.columns = ['Year', 'Season', 'Total Sale']

print(all(result ==test)) # True

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Aggregates or ranks values at the relevant grouping level

  • Strengths:

    • The Python version follows the same rule in a direct dataframe-oriented implementation.

  • Areas for Improvement:

    • The code assumes the workbook layout remains stable, so any sheet redesign would require small adjustments.

  • Gem:

    • The implementation stays close to the original workbook rule instead of adding unnecessary abstraction.

Difficulty Level

This task is moderate:

  • The business rule is readable, but the workbook still requires careful implementation to reach the expected layout.