Omid - Challenge 305

data-challenges
advanced-exercises
🔰 For each product in the question table, calculate the measure column using the following formula.
Published

March 24, 2026

Illustration for Omid - Challenge 305

Challenge Description

🔰 For each product in the question table, calculate the measure column using the following formula.

Solutions

library(tidyverse)
library(readxl)

path = "files/300-399/305/CH-305 Advanced Calculation.xlsx"
input = read_excel(path, range = "B2:D19")
test  = read_excel(path, range = "H2:I5") 

result = input %>%
  summarise(Index = diff(range(Sales)/mean(Sales[!Sales %in% range(Sales)])), .by = Product)

all.equal(result, test)
# wrong answer for product A

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Aggregates or ranks values at the relevant grouping level

    • Applies the rule iteratively until the output stabilizes

  • 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 = "300-399/305/CH-305 Advanced Calculation.xlsx"
input = pd.read_excel(path, usecols="B:D", skiprows=1, nrows=17)
test = pd.read_excel(path, usecols="H:I", skiprows=1, nrows=4)

result = input.groupby('Product')['Sales'].apply(
    lambda x: (x.max() - x.min()) / x.drop([x.idxmin(), x.idxmax()]).mean()
)

print(result)
# Different result for Product A

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Aggregates or ranks values at the relevant grouping level

    • Applies the rule iteratively until the output stabilizes

  • 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.