Python: from first line to project · Lesson 12 / 12

Your small-mission organiser

Time to bring the pieces together: data, decisions, loops, functions, files and tests. Your program chooses fictional missions that fit the available time.

Let's discover together

1
The rule visits the list in order. It skips completed missions and accepts an unfinished one if its duration fits the remaining time. It then subtracts that duration. An oversized mission is skipped; the loop continues.
2
Tico uses 10 minutes, Luma 20 and Nilo 15, but Nilo is already complete. With limit 30, Tico and Luma fit: total 30, remainder 0. With 25, only Tico fits: total 10, remainder 15.
3
The example is the core rule with prepared data. The downloadable project adds validation, missions.json, a report and tests. Extract every file, run organizer.py, then python -m unittest -v (python3 on macOS/Ubuntu).
4
Order matters: with Luma before Tico and limit 25, Luma is selected. This rule does not seek the best possible combination. Revise the order, test and explain your decision; a useful program must state its behaviour and what it does not consider.
5
The Rullst Academy editor saves one file per upload; the ZIP contains the complete starter project. To publish all files, extract it and follow PUBLISH.md. The program sends nothing to the internet. --save creates report.txt and refuses to overwrite an existing report.
6
This path uses only the standard library. For future projects with external packages, use one virtual environment per project: it separates package installations but does not make unknown code safe. Consult the venv guide before installing; do not use sudo pip or publish the .venv folder.

FROM LESSON TO PRACTICE

A guide to follow at your pace

Read the steps before using the reference below. Commands run in the indicated system’s terminal; signup happens on the official site. Rullst Academy exercises are practice and do not verify your installation or external account.

def plan(tasks, budget):
    selected = []
    remaining = budget
    for task in tasks:
        if not task["done"] and task["minutes"] <= remaining:
            selected.append(task["title"])
            remaining -= task["minutes"]
    return selected, budget - remaining, remaining

tasks = [{"title": "Tico", "minutes": 10, "done": False},
         {"title": "Luma", "minutes": 20, "done": False},
         {"title": "Nilo", "minutes": 15, "done": True}]
print(plan(tasks, 30))

Official links and next step

Optional next step: virtual environments

✦

YOUR MISSION

Run, modify and test a local project; explain its selection rule and limitations.

Now it's your turn

Discovery workshop

Read, predict, check

Compare the two versions. Show result reveals a prepared output: this panel does not run Python. Then practise with the activity file.

Mini experiment

Learning simulation: compare cards and check your predictions. The browser is not compiling Rust or starting a server.

def plan(tasks, budget):
    selected = []
    remaining = budget
    for task in tasks:
        if not task["done"] and task["minutes"] <= remaining:
            selected.append(task["title"])
            remaining -= task["minutes"]
    return selected, budget - remaining, remaining

tasks = [{"title": "Tico", "minutes": 10, "done": False},
         {"title": "Luma", "minutes": 20, "done": False},
         {"title": "Nilo", "minutes": 15, "done": True}]
print(plan(tasks, 30))

This scenario’s result

01Selected total with limit 3002Remainder with limit 3003Selected total with limit 25

Build your answers and check when you are ready.

A moment to understand

Does the rule always choose the combination using the most minutes?

Yes, any loop guarantees the best combination.Yes, because it includes every completed mission too.No. It follows order and remaining time; it does not optimise all combinations.

I need a hint

Compare outputs when reversing Tico and Luma with limit 25.

Loading your journey…

How can I tell what I learned?

Use the objectives and challenge below for reflection or a conversation with someone who can help. This is guided self-assessment: it sends no answers, awards no XP and does not automatically verify independence.

In Foundations, change an example, predict results, check a normal case and an error case, and explain your choices. If you need help, identify what to practice again.

Your transfer challenge

Download and run the project. Set the limit to 25, test another order and add a fictional mission. Add a new test and record prediction, output, change and a model limitation. Your written reflection is not automatically graded.

Keep evidence: prediction, attempt, result, an original change and what you still cannot explain. Seek feedback when possible; if studying alone, return later without copying and compare attempts.

Try again another time

After a break, explain the idea without opening the solution and try a different example. Compare with your first attempt: what can you do independently, and where do you need a hint? You may write, speak or draw; choose a way to check the same idea. Record help received, including AI, and revisit the part you need. There is no universal deadline or extra XP for this record.

Completions and XP record Rullst Academy assessments. An introductory track can help everyday life and prepare further study; alone it does not prove complete mastery or professional readiness. Level indicates depth, not age.

Take it with you

PYTHON · .py

Your Python workbench

Here you read and predict prepared outputs. To run the actual code, download the activity file, edit it on your computer and use Python. Rullst Academy grades lesson answers; it does not verify local execution.

Save and run

Extract the activity ZIP into its own folder. Open a terminal there and use your system’s command. If downloading your edited file separately, use its actual name in the command. Save before running again.

Windows

python organizer.py

macOS / Ubuntu

python3 organizer.py

My files and GitHub

The editor keeps a local draft and can send a .py file to GitHub with your confirmation. Download your edited code to preserve it. The ZIP is starter material; for the final project, also publish data and test files following PUBLISH.md.

At your own pace

My files and GitHub

Every lesson can become your own record: code, notes or a practice plan. Saving a file to GitHub is optional and does not change your XP.

Student guide

The editor and downloads open when this lesson is available to your account. Check access below or return to the track map.

Checking your access to this lesson…

Your path, step by step

Download activity materials

Download the lesson example and a workbook for your notes. The ZIP includes a guide to organizing activities in one or more repositories. Publishing is optional; eligible accounts can also use the GitHub upload button.

Your file for this lesson

Edit the example or record what you learned. This space does not run code or grade answers. The draft is saved only in this browser, separately per account; you choose when to download or upload to GitHub.

The example may be only a snippet or outline. Changing the extension does not make it a complete program. The activity ZIP contains starting material; the edited-file button downloads your text.

My code or notes

"""Small-mission organiser"""
import json
from pathlib import Path
import sys

TEXT = {
  "budget_error": "The budget must be an integer from 0 to 480 minutes.",
  "exists": "report.txt already exists and was preserved. Rename it to keep the earlier version before saving another.",
  "invalid": "Invalid missions: check the README for fields and types.",
  "none": "none",
  "read_error": "Could not finish. Check missions.json, file permissions and data rules in the README.",
  "remaining": "Time remaining",
  "saved": "Report saved to report.txt beside the program.",
  "selected": "Selected missions",
  "total": "Time used"
}

def validate(tasks):
    if not isinstance(tasks, list) or len(tasks) > 20:
        raise ValueError(TEXT['invalid'])
    for task in tasks:
        if not isinstance(task, dict):
            raise ValueError(TEXT['invalid'])
        if set(task) != {'title', 'minutes', 'done'}:
            raise ValueError(TEXT['invalid'])
        if not isinstance(task['title'], str) or not task['title'].strip() or len(task['title']) > 80:
            raise ValueError(TEXT['invalid'])
        if type(task['minutes']) is not int or not 1 <= task['minutes'] <= 180:
            raise ValueError(TEXT['invalid'])
        if type(task['done']) is not bool:
            raise ValueError(TEXT['invalid'])

def plan(tasks, budget):
    """Visits in order without changing input; does not seek the optimal combination."""
    validate(tasks)
    if type(budget) is not int or not 0 <= budget <= 480:
        raise ValueError(TEXT['budget_error'])
    selected = []
    remaining = budget
    for task in tasks:
        if not task['done'] and task['minutes'] <= remaining:
            selected.append(task['title'])
            remaining -= task['minutes']
    return {'selected': selected, 'total': budget - remaining, 'remaining': remaining}

def load_tasks(path):
    with path.open(encoding='utf-8') as file:
        tasks = json.load(file)
    validate(tasks)
    return tasks

def report(result):
    names = ', '.join(result['selected']) or TEXT['none']
    return (f"{TEXT['selected']}: {names}\n"
            f"{TEXT['total']}: {result['total']} min\n"
            f"{TEXT['remaining']}: {result['remaining']} min\n")

def save_report(path, text):
    """Creates a new report; never silently replaces an existing file."""
    with path.open('x', encoding='utf-8', newline='\n') as file:
        file.write(text)

def main():
    folder = Path(__file__).resolve().parent
    budget = 30
    try:
        tasks = load_tasks(folder / 'missions.json')
        text = report(plan(tasks, budget))
        print(text, end='')
        if '--save' in sys.argv[1:]:
            save_report(folder / 'report.txt', text)
            print(TEXT['saved'])
    except FileExistsError:
        print(TEXT['exists'])
        return 1
    except (OSError, ValueError) as error:
        print(TEXT['read_error'])
        print(type(error).__name__)
        return 1
    return 0

if __name__ == '__main__':
    raise SystemExit(main())

File format

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Your small-mission organiser

Let's discover together

A guide to follow at your pace

Official links and next step

Now it's your turn

Read, predict, check

Your transfer challenge

Try again another time

Take it with you

Your Python workbench

Save and run

My files and GitHub

Your file for this lesson

Save to my GitHub

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