Omid - Challenge 134

data-challenges
advanced-exercises
🔰 From the ‘transactions’ in the provided table, filter those that occurred in the last 7 days of the month.
Published

March 24, 2026

Illustration for Omid - Challenge 134

Challenge Description

🔰 From the “transactions” in the provided table, filter those that occurred in the last 7 days of the month.

Solutions

library(tidyverse)
library(readxl)

path = "files/CH-134 Final Week of the Month.xlsx"
input = read_excel(path, range = "C2:E27")
test  = read_excel(path, range = "G2:I5")

result = input %>%
  mutate(day = day(Date),
         month_end = ceiling_date(Date, "month") - days(1)) %>%
  filter(day >= day(month_end) - 6) %>%
  select(-day, -month_end)

all.equal(result, test, check.attributes = FALSE)
#> [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-134 Final Week of the Month.xlsx"
input = pd.read_excel(path, usecols= "C:E", skiprows= 1, nrows= 27)
test = pd.read_excel(path, usecols="G:I", skiprows=1, nrows=3).rename(columns=lambda x: x.split('.')[0])
 
input['Date'] = pd.to_datetime(input['Date'])
input['EoM'] = input['Date'] + pd.offsets.MonthEnd(0)
input = input[input['EoM'] - input['Date'] < pd.Timedelta(days=7)]

result = input[["Date","Product","Qty"]].reset_index(drop=True)

print(result.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.