Omid - Challenge 41

data-challenges
advanced-exercises
🔰 Transformation!
Published

March 24, 2026

Illustration for Omid - Challenge 41

Challenge Description

🔰 Transformation!

Solutions

library(tidyverse)
library(readxl)

input = read_excel("files/CH-041 Transformation.xlsx", range = "B2:E11")
test  = read_excel("files/CH-041 Transformation.xlsx", range = "G2:H21")

result = input %>%
  select(`Machinary Code` = 1, Col1 = 2, Col2 = 3, Col3 = 4) %>%
  pivot_longer(cols = -c(1), names_to = "col", values_to = "Product Code", values_drop_na = TRUE) %>%
  arrange(str_extract(`Product Code`, "\\d+"), col) %>%
  select(-col)

identical(result, test)
# [1] TRUE

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Reshapes the data into the grain required by the task

    • 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

input = pd.read_excel("CH-041 Transformation.xlsx", usecols="B:E", skiprows=1, nrows = 9)
test = pd.read_excel("CH-041 Transformation.xlsx", usecols="G:H", skiprows=1, nrows = 20)

result = input.copy()
# name columns
result.columns = ["Machinary Code", "Col1", "Col2", "Col3"]
result = result.melt(id_vars=["Machinary Code"], var_name="col", value_name="Product Code").dropna(subset=["Product Code"])
result = result.sort_values(by=["Product Code", "col"])
result = result.drop(columns=["col"]).reset_index(drop=True)

print(result.equals(test)) # True

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Reshapes the data into the grain required by the task

  • 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.