Excel BI - PowerQuery Challenge 262

excel-challenges
power-query
Transpose problem table into result table.
Published

March 24, 2026

Illustration for Excel BI - PowerQuery Challenge 262

Challenge Description

Transpose problem table into result table.

Solutions

library(tidyverse)
library(readxl)

path = "Power Query/PQ_Challenge_262.xlsx"
input = read_excel(path, range = "A1:J5")
test  = read_excel(path, range = "A10:C20")

result = input %>%
  pivot_longer(everything(), names_to = c(".value", "Subject"), names_sep = "-",values_drop_na = T) %>%
  select(Class, Subject, Marks)

all.equal(result, test, check.attributes = F)
#> [1] TRUE

  • Logic:

    • Reads the workbook range needed for the challenge

    • Reshapes the data into the structure required by the result table

  • Strengths:

    • The R solution stays close to the workbook logic and keeps the transformation compact.

  • Areas for Improvement:

    • The code assumes the workbook layout and selected ranges remain stable.

  • Gem:

    • The best part of the solution is choosing the right intermediate shape before formatting the final output.
import pandas as pd

path = "PQ_Challenge_262.xlsx"
input = pd.read_excel(path, usecols="A:J", nrows=5)
test = pd.read_excel(path, usecols="A:C", skiprows=9, nrows=11)

df = input.reset_index().rename(columns={'index': 'id'})
df_long = df.melt(id_vars='id', var_name='Category', value_name='Value')
df_long[['Type', 'Subject']] = df_long['Category'].str.split('-', expand=True)
df_final = df_long.pivot_table(index=['id', 'Subject'], columns='Type', values='Value', dropna=False).reset_index()
df_final = df_final.dropna(subset=['Marks', 'Class'])[['Class', 'Subject', 'Marks']].astype({'Marks': 'int64', 'Class': 'int64'}).reset_index(drop=True)

print(df_final.equals(test)) # True

  • Logic:

    • Reads the workbook range needed for the challenge

    • Reshapes the data into the structure required by the result table

  • Strengths:

    • The Python version follows the same workbook rule in a direct pandas-oriented implementation.

  • Areas for Improvement:

    • As with the R version, any workbook layout change would require small adjustments.

  • Gem:

    • The implementation stays close to the source challenge instead of adding unnecessary abstraction.

Difficulty Level

This task is moderate:

  • It combines reshaping, grouping, or parsing steps that are common in Power Query style problems.

  • The main challenge is reproducing the workbook output structure exactly.