Omid - Challenge 274

data-challenges
advanced-exercises
🔰 Group Challenge 274: Custom Grouping!
Published

March 24, 2026

Illustration for Omid - Challenge 274

Challenge Description

🔰 Group Challenge 274: Custom Grouping!

Solutions

library(tidyverse)
library(readxl)

path = "files/200-299/274/CH-274 Custom Grouping.xlsx"
input = read_excel(path, range = "B2:C18")
test  = read_excel(path, range = "G2:I18")

result = input %>%
  mutate(Group = cumsum(c(1, diff(Date) > 2)))

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

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • 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 = "200-299/274/CH-274 Custom Grouping.xlsx"
input = pd.read_excel(path, usecols="B:C", skiprows=1, nrows=16)
test = pd.read_excel(path, usecols="G:I", skiprows=1, nrows=16).rename(columns=lambda col: col.replace('.1', ''))

input['Group'] = input['Date'].diff().dt.days.gt(2).cumsum() + 1

print(input.equals(test)) # True

  • Logic:

    • Reads the workbook ranges needed for the challenge

  • 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.