Omid - Challenge 184

data-challenges
advanced-exercises
🔰 Table Transformation!
Published

March 24, 2026

Illustration for Omid - Challenge 184

Challenge Description

🔰 Table Transformation!

Solutions

library(tidyverse)
library(readxl)

path = "files/CH-184 Table Transformation.xlsx"
input = read_excel(path, range = "C2:C17", col_types = "text")
test  = read_excel(path, range = "E2:G12" , col_types = "text")

result = input %>%
  mutate(Date = ifelse(!str_detect(`Column 1`, ","), `Column 1`, NA)) %>%
  fill(Date, .direction  = "down") %>%
  filter(Date != `Column 1`) %>%
  separate(`Column 1`, into = c("Product", "Quantity"), sep = ", ") %>%
  relocate(Date, .before = Product)

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

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • 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

path = "CH-184 Table Transformation.xlsx"
input = pd.read_excel(path, usecols="C", skiprows=1, nrows=15, dtype=str)
test = pd.read_excel(path, usecols="E:G", skiprows=1, nrows=10, dtype=str)

input['Date'] = input['Column 1'].where(~input['Column 1'].str.contains(','), None).ffill()
input = input[input['Date'] != input['Column 1']]
input[['Product', 'Quantity']] = input['Column 1'].str.split(', ', expand=True)
input = input[['Date', 'Product', 'Quantity']].reset_index(drop=True)

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 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.