The bear hunt

Posted on February 18, 2015 by Administrator Posted in Computer Science, Python - Beginner, Python Challenges

This challenge is inspired from Michael Rosen and Helen Oxenbury’s children book “We are going on a bear hunt”. In this story, a family skids down a grassy slope, swishes across a river, sludges through mud and finally sees a bear who chases them all the way back to their home.

This story is based on a repetitive verse where the same verse is repeated several times and each time only a few words are changed.

So let’s see how we could apply our programming skills to print the words or lyrics of a repetitive story or song.

Learning Objectives

In this post we will investigate how to use a subroutine do write code more efficiently. We will also pass parameters to our subroutine.

You will also use string concatenation techniques to join two strings together.

Investigate the code below. See how we have defined a subroutine called printVerse() and used two parameters for this subroutine: obstacle and onomatopoeia (a word that represents a sound: e.g. splosh).

Challenge #1

Using a similar approach write a piece of code to print the lyrics of the following song:

Five little speckled frogs
Sat on a speckled log
Eating some most delicious bugs – yum, yum
One jumped into the pool
Where it was nice and cool
Now there are four green speckled frogs – glub, glub.

Four little speckled frogs
Sat on a speckled log
Eating some most delicious bugs – yum, yum
One jumped into the pool
Where it was nice and cool
Now there are three green speckled frogs – glub, glub.

Three little speckled frogs
Sat on a speckled log
Eating some most delicious bugs – yum, yum
One jumped into the pool
Where it was nice and cool
Now there are two green speckled frogs – glub, glub.

Two little speckled frogs
Sat on a speckled log
Eating some most delicious bugs – yum, yum
One jumped into the pool
Where it was nice and cool
Now there are one green speckled frogs- glub, glub.

One little speckled frogs
Sat on a speckled log
Eating some most delicious bugs – yum, yum
One jumped into the pool
Where it was nice and cool
Now there are no green speckled frogs – glub, glub.

Challenge #2

Using a similar approach write a piece of code to print the words of the “10 ladybugs” story by Melanie Gerth and Laura Huliska-Beith:

Ten little ladybugs sitting on a vine,
along came a butterfly – then there were…

Nine little ladybugs skipping on a gate,
along came a caterpillar – then there were…

Eight little ladybugs looking up at heaven,
along came a bird – then there were…

Seven little ladybugs resting on sticks,
along came a grasshopper – then there were…

Six little ladybugs flying near a hive,
along came a bumble bee – then there were…

Five little ladybugs sleeping by the shore,
along came a fish – then there were…

Four little ladybugs climbing up a tree,
along came a turtle – then there were…

Three little ladybugs drinking up dew,
along came a duck – then there were…

Two little ladybugs basking in the sun,
along came a frog – then there was…

One little ladybug sitting all alone,
along came a breeze – then she was HOME!

Tagged with: Procedure, Python, subroutine

Logic Gates Diagrams

Posted on February 15, 2015 by Administrator Posted in Computer Hardware, Computer Science, Computing Concepts, Physical Computing

Learning Objectives

In this post you will practise drawing logic gates diagrams using the following logic gates:

AND Gate
OR Gate
XOR Gate
NOT Gate

First you will need to learn the shapes/symbols used to draw the four main logic gates:

Symbol	Logic Gate

Logic Gate Diagrams

Your Task

Use our logic gates diagram tool to create the diagrams as follow: (Click on the following equations to draw their logic gates diagrams)

Logic Gates Diagram CreatorCreate your own logic gates diagram

Dry Run Testing & Trace Tables

Posted on February 15, 2015 by Administrator Posted in A Level Concepts, A Level Quiz, Algorithms, Algorithms (GCSE), Computer Science, Computing Concepts

Learning Objectives

You have just completed a piece of code but when you run it, it does not behave as expected.

One way to check and troubleshoot your code is to perform a dry run using a trace table.

Trace tables are used by programmers to track the values of variables as they change throughout the program. This is useful when a program is not producing the desired result.

Context / Starter activity

A primary teacher likes to start her maths lesson by displaying a number sequence maths challenge on the board. Here are the last three challenges she has used with her class. Can you solve these?

Number Sequence #1: number-sequence-2
Number Sequence #2: number-sequence-3 Number Sequence #3: number-sequence-1

The primary teacher decided to create some Python script to help them create similar number sequences.

Here is the pseudo-code for her first script:

number = 3
PRINT number
FOR  i  from 1 to 3:
      number = number + 5
      PRINT number
PRINT "?"

To make sure her script is working she decided to complete a dry run test using a trace table. See animation below:
trace-table-s

View the complete trace table.

Challenge #1

Step 1: Complete the trace table for the following script:

number = 5
PRINT number
FOR  i  from 1 to 3:
      number = number + i
      PRINT number
PRINT "?"

Step 2: Implement this code using a high level programming language (e.g. Python) and compare your trace table with your actual output of your program.

Challenge #2

Step 1: Complete the trace table for the following script:

number1 = 2
number2 = 5
PRINT number1
PRINT number2
FOR  i  from 1 to 4:
      number1 = number1 + number2
      PRINT number1
      number2 = number1
PRINT "?"

Step 2: Implement this code using a high level programming language (e.g. Python) and compare your trace table with your actual output of your program.

Challenge #3

Think of your own number sequences. Write the pseudo-code, the trace table and implement them using a high level programming language (e.g. Python).

Modular Design

Posted on February 11, 2015 by Administrator Posted in Computer Science, Python - Intermediate, Python Challenges

lego-bricks

Learning Objectives

When working on larger projects, you will need to carefully plan ahead the structure of your applications/programs. You will have to break down your application into smaller modules and will most likely want to give your end-users the option to navigate through all these sub-modules.

This top-down/modular approach to designing and structuring your applications will enable you to break down what may seem like a very complex project into smaller, achievable modules that you will complete progressively one at a time.

In order for your end-user to access to all the modules available you may be willing to offer a menu structure. This could use drop down menu bars, touch screen icons/menus or a text-based menu system used with a command prompt to interact with the end-user.

In this challenge we will focus on this latest approach: a text-based menu system with a command prompt to retrieve user inputs/choices. Note that the logic behind this would be similar with other types of menus based on a Graphical User Interface or touchscreen or even with a voice activated interface.

Context

We are about to create our first video game and have produced the following top/down modular design for it.

Let’s look at how this would look like once implemented using Python:

Option #1:

Option #2:

This option is a bit more complex and enables the end-user to navigate between menus and sub-menus.

Option #3:

This code is exactly the same as the code used for option #2. However by splitting the code into mutilple .py files it looks neater and easier to maintain.

When using a modular approach to breaking down a large project we often spread the code accross multiple files. It makes troubleshooting a lot easier.

Improvements

There are many ways we could improve this menu system such as:

Add validation methods to make sure the user only enters the right type of menu options,
Add a Graphical User Interface to make this menu more visual. To do so we could use a Python library such as PyGame or TkInter.

US Population

Posted on February 10, 2015 by Administrator Posted in Computer Science, Python - Intermediate, Python Challenges, Solved Challenges

Your challenge is to write a Python program that will read through the data from the US States.txt text file provided below in order to find out:

The total population in the USA (by adding the population of each of the 51 states,
The average population per state,
The state which has the highest population,
The state which has the lowest population,
A list of all 51 states with their population as a percentage of the total US population.

The given text file is a CSV file (Comma Separated Values) with the following fields:

State , State Code , Population (in year 2000)

US States.txt

Learning Objectives

By completing this challenge you will learn how to read through and extract data from a CSV file. You may want to read this blog post about handling text files using Python first.

Complete the code

The code below read through the text file line by line using a for loop. For each line it extracts the data using the split() method.

Challenge #2: Compare State Population Game

Use this text file to create a Python game where the computer randomly displays two states on the screen (with their full name and their 2-letter code) and asks the user to guess which of the two states has the largest population. If the user guesses it right, they score one point otherwise they lose one point.

Solution...

The solution for this challenge is available to full members!
Find out how to become a member:
➤ Members' Area

Tagged with: File Handling, Python

UK Postcodes – Distance Calculator

Posted on February 5, 2015 by Administrator Posted in Computer Science, Python - Advanced, Python Challenges, Solved Challenges

Challenge

Your challenge is to write a Python program that asks the end-user to enter two valid UK postcodes and in return displays the distance in miles or km between those two postcodes.

To complete this challenge you will first find the exact longitude and latitude of both the postcodes entered by the end user. The following text file contains a list of all the UK outer codes (first part of a postcode) with their exact longitude and latitude.

UK Postcodes.csv

Once your program will have retrieved the longitude and latitude of both locations (postcodes) it will use the Haversine formula to calculate the exact distance between these two locations.

Haversine Formula

The Haversine formula is an equation important in navigation, giving great-circle distances between two points on a sphere from their longitudes and latitudes.

This formula will enable us to calculate the shortest distance over the earth’s surface – giving an ‘as-the-crow-flies’ distance between the two locations (ignoring any hills they fly over, of course!).

You can read more about the haversine formula on this wikipedia page.

To complete this challenge you will also need to investigate the use of trigonometric functions from the math library.

Note that when completing this challenge, longitudes and latitudes are given in degrees, not radians.

Once completed you can check your distances online.

Solution...

The solution for this challenge is available to full members!
Find out how to become a member:
➤ Members' Area

Tagged with: File Handling, Linear Search, Python Challenge

Team Generator

Posted on February 4, 2015 by Administrator Posted in Computer Science, Python - Intermediate, Python Challenges, Solved Challenges

Context

A primary school teacher has a class of 30 pupils. (See attached file called class.txt).
They would like you to create a Python script that will help them make teams for group activities.

Your program should ask the number of teams the teacher needs (between 2 and 6), read the names of the pupils from the text file and assign pupil randomly to teams. However there should be roughly (or exactly when possible) the same number of pupils in each team.

class.txt

Learning Objectives

In this challenge you will learn how to read data from a text file. The file given is a CSV file. CSV stands for Comma Separated Values. Which means each record (pupil) is stored on a line of the file. On each line the two fields (firstname and lastname) are separated using a comma.

Before attemtping to complete this challenge, make sure you read about file handling operations using Python.

Complete the code

Challenge #2: Random Name Picker

The primary teacher sometimes asks questions to the whole class. They would like to have a program that helps them randomly pick a name from their class list. They would like to make sure that once a name has been picked up once, they cannot be picked up a second time.

Using the class.txt file, write a Python program to meet the teacher’s requirements.

Solution...

The solution for this challenge is available to full members!
Find out how to become a member:
➤ Members' Area

Class Register

Posted on February 1, 2015 by Administrator Posted in Computer Science, Python - Intermediate, Python Challenges, Solved Challenges

class-register

Learning Objectives

In this challenge we are going to focus on accessing a text file in Python to:

Read the content of the file line by line,
Write data to a new file.

Before completing this challenge, you should read about the main file handling operations using Python.

Your Challenge

Your challenge consists of writing a Python script that could be used by a teacher to take the register at the beginning of the lesson.

Your program will need to:

Read the text file called classList.txt, line by line.
For each student (line of the text file) the program should ask the teacher if the pupil is pesent (“/” code), absent for medical reasons or illness (“M” code), on a school trip (“T” code), or absent with no reason provided yet (“X” code).
The program should store the teacher’s input alongside with the name of each pupil into a new text file called “register.txt”.

To complete this challenge you will need to use the class list text file:

ClassList.txt

Python Code

Complete the Python code below…

Solution...

The solution for this challenge is available to full members!
Find out how to become a member:
➤ Members' Area

Times Table Challenge

Posted on January 31, 2015 by Administrator Posted in Computer Science, Python - Intermediate, Python Challenges, Solved Challenges

Learning Objectives

By completing this challenge you are going to perform arithmetic operations in Python. You will also learn how to manipulate counted loops (for loops) and how to combine loops together using nested loops.

Times Table

Look at the code below. It’s asking the user to type a number and then it displays the times table for that number using a for loop.

Nested Loops

When you insert a loop within a loop, you are using “nested loops”.
Check the code below that uses a nested loop.

Challenge #1

Tweak the code above to display a full times table:

Challenge #2

Tweak your code to display a number grid as follows:

Solution...

The solution for this challenge is available to full members!
Find out how to become a member:
➤ Members' Area

Higher or Lower Game

Posted on January 27, 2015 by Administrator Posted in Computer Science, Python - Intermediate, Python Challenges

Higher-Or-Lower For this challenge you will design and write a program to play against the computer.
The computer will display a random number between 1 and 1000. It will then ask the end-user whether they believe the next number will be higher or lower. The program will then generate the next number. If the user guessed right (e.g. the next number is higher or lower than the previous one) then the user scores one point. The game stops when the user guesses it wrong.

Learning Objectives

By completing this challenge you are going to use selection (IF statements) and iteration (While loop). You will use comparison operators such as > , < and == to compare numbers. You will use variables to store the value of random numbers, retrieve user input and keep and increment a score as the game progresses.

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Learning Objectives

Challenge #1

Challenge #2

Learning Objectives

Logic Gate Diagrams

Your Task

Learning Objectives

Context / Starter activity

Challenge #1

Challenge #2

Challenge #3

Learning Objectives

Context

Option #1:

Option #2:

Option #3:

Improvements

Learning Objectives

Complete the code

Challenge #2: Compare State Population Game

Solution...

Challenge

Haversine Formula

Solution...

Context

Learning Objectives

Complete the code

Challenge #2: Random Name Picker

Solution...

Learning Objectives

Your Challenge

Python Code

Solution...

Learning Objectives

Times Table

Nested Loops

Challenge #1

Challenge #2

Solution...

Learning Objectives

Complete the Python Code

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