Omid - Challenge 179

data-challenges
advanced-exercises
🔰 Product ID A B Question Quantity Date Result Column1
Published

March 24, 2026

Illustration for Omid - Challenge 179

Challenge Description

🔰 Product ID A B Question Quantity Date Result Column1

Solutions

library(tidyverse)
library(readxl)

path = "files/CH-179 Reshape a table.xlsx"
input = read_excel(path, range = "B2:F10") %>% as.matrix()
test  = read_excel(path, range = "H2:J14")

result = input %>%
  t() %>%
  as.vector() %>%
  na.omit() %>%
  matrix(ncol = 3, byrow = TRUE) %>%
  as.data.frame() %>%
  setNames(c("Date", "Product ID", "Quantity")) %>%
  mutate(Date = as.POSIXct(janitor::excel_numeric_to_date(as.numeric(Date))),
         Quantity = as.numeric(Quantity))

all.equal(result, test, check.attributes = F)
#> [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
import numpy as np

path = "CH-179 Reshape a table.xlsx"
input = pd.read_excel(path, usecols="B:F", skiprows=1, nrows=8).to_numpy()
test = pd.read_excel(path,  usecols="H:J", skiprows=1, nrows=13)

result_df = pd.DataFrame(input.flatten()[~pd.isna(input.flatten())].reshape(-1, 3), columns=["Date", "Product ID", "Quantity"])
result_df["Quantity"] = result_df["Quantity"].astype(np.int64)

print(result_df.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.