Omid - Challenge 383

data-challenges
advanced-exercises
🔰 Challenge 383: Filter!
Published

March 24, 2026

Illustration for Omid - Challenge 383

Challenge Description

🔰 Challenge 383: Filter!

Solutions

library(tidyverse)
library(readxl)

path <- "300-399/383/CH-383 Filter.xlsx"
input <- read_excel(path, range = "B3:B10")
test <- read_excel(path, range = "F3:F5")

is_valid <- function(s) {
  digits <- str_extract_all(s, "\\d")[[1]] %>% as.integer()
  digits[1] %% 2 == 0 && digits[length(digits)] %% 2 == 1
}

result <- input %>%
  filter(map_lgl(ID, is_valid))

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

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • 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 = "300-399/383/CH-383 Filter.xlsx"
input = pd.read_excel(path, usecols="B", skiprows=2, nrows=8)
test = pd.read_excel(path, usecols="F", skiprows=2, nrows=2)

def is_valid(s):
    digits = [c for c in str(s) if c.isdigit()]
    return int(digits[0]) % 2 == 0 and int(digits[-1]) % 2 == 1

result = input[input["ID"].apply(is_valid)].reset_index(drop=True)

print(result["ID"].equals(test["ID.1"]))
# True

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Applies the rule iteratively until the output stabilizes

  • 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.