Worksheet

F4.5 Libraries and your own modules

Functions and structured code · GCSE · OCR J277 2.2.3, AQA 8525 3.2.10, Edexcel 1CP2 6.6.1 · about 15 min

What this lesson is about

import, Python's own libraries, and a module file of your own.

• import
• Three ways to import
• Libraries you already know
• Your own module
• Why write modules?

Questions 5 marks in all

1. [1 mark]What does this program print?

   import math
   print(math.sqrt(49))

2. [1 mark]What does this program print?

   from math import floor, ceil
   print(floor(2.7), ceil(2.1))

3. [1 mark]Which are benefits of using a library?

   Tick every answer that is true.

   1. AIt saves writing the code yourself
   2. BIts code has already been tested
   3. CYou can use complex features without knowing how they work
   4. DIt makes every program shorter than 10 lines

4. [1 mark]A program says import moves and calls moves.square(20). Where is square defined?

   1. AIn a file called moves.py
   2. BInside the program itself
   3. CIn the math library
   4. DNowhere: it causes an error

5. [1 mark]Why does moves.py need its own from bugbot import * line?

   1. AA module gets the robot's commands only by importing them itself
   2. BEvery Python file must start with it
   3. CIt connects to the robot twice
   4. DIt does not need it

The task: use your module

Finish square(size) in moves.py above so it drives a square and ends where it started (replace pass). Then, in the task, import moves and use it to drive a square of 20 cm and then a square of 35 cm. Do not write the square's drives in the task program itself.

# the two lines every program starts with: the commands, then the robot
from bugbot import *
connect()

import moves

moves.square(20)

Plan your program here, then type it in and press Run.

Do it on the robot
www.bugbotlab.com/learn/f4-5-libraries-and-modules/
The simulator checks it and tells you when it passes. Nothing to install, no account.

Challenges

1. Add a function triangle(size) to moves.py and use it from a Try-it cell.
2. Plan a module sounds.py on paper: list the functions a robot program would want from it, with their parameters.
3. Use math.hypot to print how far the robot is from where it started after a zigzag.