Omid - Challenge 329

data-challenges
advanced-exercises
🔰 Calculate the end date equal to the sum of Start date time and Duration
Published

March 24, 2026

Illustration for Omid - Challenge 329

Challenge Description

🔰 Calculate the end date equal to the sum of Start date time and Duration

Solutions

library(tidyverse)
library(readxl)
library(lubridate)

path <- "300-399/329/CH-329 Date Calculation.xlsx"
input <- read_excel(path, range = "B2:C8")
test  <- read_excel(path, range = "D2:D8") %>%
  mutate(`End Time` = dmy_hms(`End Time`))

result <- input %>%
  mutate(
    `Start Date` = dmy_hms(`Start Date`)
  ) %>%
  separate(`Duration [d.h:m:s]`, into = c("dh", "m", "s"), sep = ":", extra = "merge") %>%
  separate(dh, into = c("d", "h"), sep = "\\.", convert = TRUE) %>%
  mutate(across(c(d, h, m, s), as.numeric)) %>%
  mutate(
    calculated_end_date = `Start Date` +
      days(d) + hours(h) + minutes(m) + seconds(s)
  )

result$calculated_end_date == test$`End Time`
# [1] FALSE  TRUE  TRUE  TRUE  TRUE  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 = "300-399/329/CH-329 Date Calculation.xlsx"
input = pd.read_excel(path, usecols="B:C", nrows=6, skiprows=1)
test = pd.read_excel(path, usecols="D", nrows=6, skiprows=1)
test["End Time"] = pd.to_datetime(test["End Time"], dayfirst=True)

input["Start Date"] = pd.to_datetime(input["Start Date"], dayfirst=True)

dhms = input["Duration [d.h:m:s]"].str.split(":", expand=True)
dh = dhms[0].str.split(".", expand=True)
d = dh[0].astype(int)
h = dh[1].astype(int)
m = dhms[1].astype(int)
s = dhms[2].astype(int)
input[["d", "h", "m", "s"]] = pd.DataFrame({"d": d, "h": h, "m": m, "s": s})

input["calculated_end_date"] = (
    input["Start Date"]
    + pd.to_timedelta(input["d"], unit="D")
    + pd.to_timedelta(input["h"], unit="h") 
    + pd.to_timedelta(input["m"], unit="m")
    + pd.to_timedelta(input["s"], unit="s")
)

print(input["calculated_end_date"] == test["End Time"])

  • 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.