Omid - Challenge 154

data-challenges
advanced-exercises
🔰 Date Price index
Published

March 24, 2026

Illustration for Omid - Challenge 154

Challenge Description

🔰 Date Price index

Solutions

library(tidyverse)
library(readxl)

path = "files/CH-154 Custom Index Column.xlsx"
input = read_excel(path, range = "B2:C13")
test  = read_excel(path, range = "E2:G13")

result = input %>%
  mutate(index = cumsum(c(0, diff(Date)) != 1)) 

all.equal(result$index, test$index)
#> [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 = "CH-154 Custom Index Column.xlsx"
input = pd.read_excel(path, usecols="B:C", skiprows=1, nrows=11)
test = pd.read_excel(path, usecols="E:G", skiprows=1, nrows=11)

input['Date'] = pd.to_datetime(input['Date'])
input['index'] = (input['Date'].diff() != pd.Timedelta(days=1)).cumsum().astype('int64')

print(all(input['index'] == test['index'])) # 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.