Omid - Challenge 343

data-challenges
advanced-exercises
🔰 Challenge 343: Custom Grouping!
Published

March 24, 2026

Illustration for Omid - Challenge 343

Challenge Description

🔰 Challenge 343: Custom Grouping!

Solutions

library(tidyverse)
library(readxl)

path <- "300-399/343/CH-343 Custom Grouping.xlsx"
input <- read_excel(path, range = "B3:C12")
test <- read_excel(path, range = "F3:G7")

result = input %>%
  mutate(ID = str_sub(ID, 1, 2)) %>%
  summarise(Sales = sum(Sales), .by = ID)

all.equal(result, test)
# [1] 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

    • Parses the text patterns directly instead of relying on manual cleanup

  • 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
import numpy as np

path = "300-399/343/CH-343 Custom Grouping.xlsx"
input = pd.read_excel(path, usecols="B:C", skiprows=2, nrows=10)
test = (
    pd.read_excel(path, usecols="F:G", skiprows=2, nrows=4)
    .rename(columns=lambda col: col.replace('.1', ''))
    .sort_values(by=['Sales', 'ID'], ascending=[True, True])
    .reset_index(drop=True)
)
input['ID'] = input['ID'].str[:2]
result = input.groupby('ID', as_index=False).agg({'Sales': 'sum'})

print(result.equals(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 core logic is clear, but the correct transformation pattern is not obvious from the raw input.

  • The challenge combines multiple reshaping, grouping, or parsing steps.