Omid - Challenge 379

data-challenges
advanced-exercises
🔰 Challenge 379: Filter!
Published

March 24, 2026

Illustration for Omid - Challenge 379

Challenge Description

🔰 Challenge 379: Filter!

Solutions

library(tidyverse)
library(readxl)

path <- "300-399/379/CH-379 Filter.xlsx"
input <- read_excel(path, range = "B3:B10")
test <- read_excel(path, range = "F3:F8")

digit_sum <- function(x, pattern) {
  x |>
    str_extract_all(pattern) |>
    map_dbl(~ sum(as.numeric(.x), na.rm = TRUE))
}

result <- input |>
  mutate(
    even_sum = digit_sum(ID, "[02468]"),
    odd_sum = digit_sum(ID, "[13579]")
  ) |>
  filter(xor(even_sum < 10, odd_sum > 10))

all.equal(result$ID, test$ID)
# GH9087 and PQ1357 dont meet condition of "either or",
# but met if there would be "normal or" == "one or the other or both".

  • 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
import re

path = "300-399/379/CH-379 Filter.xlsx"
input = pd.read_excel(path, usecols="B", skiprows=2, nrows=8)
test = pd.read_excel(path, usecols="F", skiprows=2, nrows=5).rename(columns=lambda c: re.sub(r"\.\d+$", "", c))

def digit_sum(ids, pat):
    return [sum(int(d) for d in re.findall(pat, x)) for x in ids]

result = input.copy()
result["even_sum"] = digit_sum(result["ID"], r"[02468]")
result["odd_sum"]  = digit_sum(result["ID"], r"[13579]")
result = result[result["even_sum"].lt(10) ^ result["odd_sum"].gt(10)][["ID"]].reset_index(drop=True)

print(result.equals(test))
# GH9087 and PQ1357 dont meet condition of "either or", 
# but met if there would be "normal or" == "one or the other or both".

  • Logic:

    • Reads the workbook ranges needed for the challenge

    • Parses the text patterns directly instead of relying on manual cleanup

    • 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.