My mp3 playlist

Posted on January 6, 2015 by Administrator Posted in Computer Science, Python - Intermediate, Python Challenges

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,
Append data at the end of the file,
Write into a new text file.

To complete these challenges we recommend you to use Coding Ground which let you code online and use multiple files. You will first need to create a text file to copy the content of the playlist (from the text file given below)

Challenge #1

Your first challenge consists of writing a Python script that will read the following text file, one line at a time and display the content of each line on screen.

My Playlist.txt

As you are willing to complete this challenge we assume that you already have some good Python skills. To learn more about accessing text files in Python, you will first need to do some research on the Internet.

Challenge #2

Your second challenge consists of opening the text file with Python in “write” mode to add the following song at the end of the playlist:

“Happy” by Pharrell Williams – Duration: 3:52
You will need to research the Intenet on how to write at the end of a text file.

Challenge #3

For your third challenge you will edit the playlist so that the song “Happy” by Pharrell Williams appear in third position.

Tagged with: File Handling, Python Challenge

Countdown

Posted on December 30, 2014 by Administrator Posted in Computer Science, Python - Intermediate, Python Challenges

countdown_animated The aim of this blog post is to create a countdown timer that will display the numbers on screen using a 7-segment display. A lot of electronic devices use this approach to display numbers on a LED or LCD screen. (Watch, alarm clock, calculator etc.)

First we need to investigate how the 7-segment display works. You will find this page quite useful.

Typically 7-segment displays consist of seven individual coloured LED’s (called the segments). Each segment can be turned on or off to create a unique pattern/combination. Each segment is identified using a letter between A to G as follows:

7segments

The following truth table shows which segments need to be on to display the digits from 0 to 9:

Digit	A	B	C	D	E	F	G
	1	1	1	1	1	1	0
	0	1	1	0	0	0	0
	1	1	0	1	1	0	1
	1	1	1	1	0	0	1
	0	1	1	0	0	1	1
	1	0	1	1	0	1	1
	1	0	1	1	1	1	1
	1	1	1	0	0	0	0
	1	1	1	1	1	1	1
	1	1	1	1	0	1	1

Your Challenge

The code below is used to display a countdown timer counting from 5 to 0 and using the 7-segment approach to display the numbers.

Your challenge consists of using the truth table given in this post to start your countdown from 9 (instead of 5).

Challenge #2:

With 7 segments there are 128 possible symbols. Some can be used to represent letters. For instance:

tmp-10

Tweak the code above to write a message using the 7-segment display.

Start with the following message “Hello” (HELLO)

Morse Code Encoder

Posted on December 23, 2014 by Administrator Posted in Computer Science, Python - Intermediate, Python Challenges, Solved Challenges

The aim of this challenge is to create a Morse code converter that lets the user enter any message. The program should then display the message in Morse code. To complete this challenge you will need to know how Morse code works. If the information given below is not clear enough you can find out more about Morse code on this wikipedia page.

Morse code is a method of transmitting text information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment.

Each character (letter or numeral) is represented by a unique sequence of dots and dashes. The duration of a dash is three times the duration of a dot.

For this challenge we will be using the international Morse code as follows:

Learning Objectives

By completing this challenge we are going to learn about Python dictionaries.
In Python, a dictionary consists of pairs (called items) of keys and their corresponding values.

Python dictionaries are also known as associative arrays or hash tables. The general syntax of a dictionary is as follows:

myDictionary = {"Red": "#FF0000", "Green": "#00FF00", "Blue": "#0000FF"}
print("The colour code for Green is:")
print(myDictionary["Green"])

Morse Code Encoder

Check the code below to encore your own message into Morse code:

Challenge #1:

Complete the code above to add the Morse code for number digits between 0 and 9 as follows:

Challenge #2: Morse Code Decoder

Write a program that enables you to decode a message written in Morse code. For instance, your program should be able to decode the following message:
… — … -.-. –.- -.. – .. – .- -. .. -.-. .– . .- .-. . … .. -. -.- .. -. –. ..-. .- … –

Challenge #3: Sending Light Signals

Check the following code used to simulate a lamp going on and off to reproduce an SOS call in Morse code: … — …

Combine this code with the code from the Morse code encoder to create light signals in Morse code. Remember the rules of Morse code:

Each character (letter or numeral) is represented by a unique sequence of dots and dashes.
The duration of a dash is three times the duration of a dot.
Each dot or dash is followed by a short silence, equal to the dot duration.
The letters of a word are separated by a space equal to three dots (one dash).
The words are separated by a space equal to seven dots.

Solution...

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

Tagged with: cryptography

Home Alone – Kevin is not here!

Posted on December 21, 2014 by Administrator Posted in Computer Science, Python - Advanced, Python Challenges

First, let’s watch this short video clip from the movie Home Alone 2.

This video clip highlights a typical case of recursion.

Recursive Functions

A recursive function is a function which calls itself.
To make sure that a recursive function does not loop indefinitely it needs a stopping condition to check if a condition is met: If it is, it should stop calling itself.

In this challenge we are writing a recursive function that asks the person standing next to us to “pass this bag to Kevin”. Each person in the queue forwards this message by calling the same function. However if we reach the end of the queue or if we reach Kevin then we stop asking. So in this case we have two conditions that can stop the recursion: we reach the end of the queue/list or we reach Kevin.

Give this to Kevin: Recursive Function

For more examples based on recursive functions, check this post.

The Gruffalo

Posted on December 21, 2014 by Administrator Posted in Computer Science, Python - Beginner, Python Challenges, Solved Challenges

This challenge is inspired from Julia Donaldson and Alex Sheffler’s children book: “The Gruffalo”.

In this story a little mouse describes a ferocious animal/monster called a “Gruffalo” to scare other dangerous animals (fox, snake, owl) she encounters while taking a walk in the forest.

This little mouse being very imaginative she uses plenty of frightening adjectives to describe this fictional animal.

In this challenge you are going to write a program that generates a description of a Gruffalo. Each time the program is run, a new description will be generated.

Learning Objectives:

By investigating this challenge you are going to further improve your skills at:

Using lists and accessing values of a list randomly,
Concatenating strings together to create a longer string.

Remember, in Python, a list is a collection of values. It uses [square brackets].
For instance:

colourList = ["red","blue","yellow","green","magenta"]

To access a random value from this list, you can use the random.choice method.

For instance:

colourList = ["red","blue","yellow","green","magenta"]
randomColour=random.choice(colourList)

Challenge

Complete the code below to describe your gruffalo further:

Has he got terrible teeth in his terrible jaws?
Has he got a poisonous wart at the end of his nose?
Has he got a black tongue and purple prickles all over his back?

Each time you run this code it will create a new description!

Solution...

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

Tagged with: Python Challenge, String Manipulation

The Twelve Days of Christmas

Posted on December 20, 2014 by Administrator Posted in Computer Science, Python - Intermediate, Python Challenges

“The Twelve Days of Christmas” is an English Christmas carol that enumerates in the manner of a cumulative song a series of increasingly grand gifts given on each of the twelve days of Christmas.

Let’s look at how we could use Python to write the lyrics of a cumulative song.

Learning Objectives

By investigating this program you will understand more how to use lists in Python and how to use loops to iterate through all the values of a list.

Remember, in Python, a list is a collection of values. It uses [square brackets].
For instance:

giftList = ["Teddy Bear","Toy car","Electric Train"]

To find out the number of items in a list we can use the len method.

giftList = ["Teddy Bear","Toy car","Electric Train"]
numberOfGifts = len(giftList)

To iterate through all the items in a list we can use a for loop.

For instance:

giftList = ["Teddy Bear","Toy car","Electric Train"]
numberOfGifts = len(giftList)

print("My Chritmas wish list to Santa:")
for i in range(0,numberOfGifts):
  print(giftList[i])

We can then use string concatenation techniques to add punctuation:

giftList = ["Teddy Bear","Toy car","Electric Train"]
numberOfGifts = len(giftList)

letterToSanta = "Dear Santa,\n\nThis is my wish list for Christmas:\n"
for i in range(0,numberOfGifts):
  letterToSanta += "\n    " + giftList[i] + ","

letterToSanta = letterToSanta[:-1] + "." #Replace last comma with a full stop.
letterToSanta += "\n\nWishing you a Merry Christmas!"

print(letterToSanta)

Python Script for The Twelve Days of Christmas:

The code below is used to write the lyrics of this Christmas carol.

Challenge:

Your challenge consists of re-using this script to adapt it to create the lyrics of another cumulative song such as:

Happy New Year!

Posted on December 18, 2014 by Administrator Posted in Computer Science, HTML, CSS & JavaScript

Learning Objectives

In this challenge you will learn how to format text using CSS including how to:

Changing font style,
Changing font color,
Changing font weight,
Changing text to italic,
Underlining text.

We will also investigate the use of borders, border radius and background colours as well as padding and margin options.

CSS Box Model

To understand how margin, borders and padding works you need to understand the CSS Box Model. Click on this picture to find out more:

Your Task

Complete the HTML and CSS code below to finalise customising the look & feel of this “Happy New Year!” message.

See the Pen MYevOP by 101 Computing (@101Computing) on CodePen.

Tagged with: CSS, HTML

Digicode – CSS Challenge

Posted on December 15, 2014 by Administrator Posted in Computer Science, HTML, CSS & JavaScript

In this challenge you are going to use CSS to create your own digicode keypad.

Learning Objectives

By completing this challenge you will familiarise yourself with CSS pseudo-classes.
A pseudo-class is used to define a special state of an element.
For example, it can be used to:

Style an element when a user rolls over it.
Style visited and unvisited hyperlinks differently.
Style active elements (for instance when a user clicks on an element, it becomes active).

The syntax of pseudo-classes:

selector:pseudo-class {
    property:value;
}

For instance to create a roll-over effect for hyperlinks:

A:hover {
    color:#FF0000;
}

You can also have a pseudo-class for when a link or button is active (being clicked on):

A:active {
    font-weight:bold;
}

Find out more about pseudo-classes.

Let’s see the code in practice by completing this challenge.

Your Task

Tweak the code below to create your own look & feel for your “digicode”:

See the Pen LENvrN by 101 Computing (@101Computing) on CodePen.

Scrabble Challenge

Posted on December 15, 2014 by Administrator Posted in Computer Science, Python - Advanced, Python Challenges, Solved Challenges

This challenge consists of creating a computer program that displays a random selection of 7 letters to the end-user. Each letter is given a value based on the values used in the game of Scrabble.

The user is then asked to enter a word made up using the given letters used in any order.

The program should check that the word given by the end user consists of the right letters and then calculate the score of the word based on the letter used and their values.

For instance the word “CODING” would give a score of 3 + 1 + 2 + 1 + 1 + 2 = 10

Note that for this challenge we assume that the user will give a valid English word! We will not expect the computer to check that the word actually exists in the English Language.

Learning Objectives

By completing this challenge you will discover the difference between a list and a dictionary, two data structures that can be used in Python.

You may want to read more about [lists] and about {dictionaries} first.

Complete the code

We have started the code for you. As you can see this code uses a list called randomLetters to store the value of the 7 randomly picked letters.
It also uses a dictionary called letterValues to store the value of each letter of the alphabet (Based on the game of Scrabble).

You now need to complete this code to finish the game…

Solution...

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

Tagged with: Python Challenge, String Manipulation

Battleship Challenge

Posted on December 14, 2014 by Administrator Posted in Computer Science, Python - Advanced, Python Challenges, Solved Challenges

For this challenge we are not going to recreate a full battleship game. Instead we are going to focus on randomly placing the ships on the grid using an algorithm.

The code given below uses Python Turtle to draw the full grid.
The grid is a 10 by 10 array. As Python does not support 2-dimensional arrays we created a list of lists instead.

The grid is first initialised with the value 0 in each cell of the array.
To place a ship you change the value from 0 to 1 on all the required cells.

This program uses four functions called:

addSubmarine to place a submarine (ship of size 1) on the grid. This function is already completed.
addDestroyer to place a destroyer (ship of size 2) on the grid. You need to complete this function.
addCruiser to place a cruiser (ship of size 3) on the grid. You need to complete this function.
addAircraftCarrier to place an aircraft carrier (ship of size 4) on the grid. You need to complete this function.

Note that when placing a destroyer, cruiser or aircraft carrier, you can either place it horizontally or vertically. However before placing the ship on the grid you must ensure that:

All the cells used to place the ship are empty (No conflict with another ship on the grid),
The ship will not go off the 10 by 10 grid.

The code so far…

Solution...

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

Tagged with: 2D Array, array, List, Python Challenge, Python Turtle

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Learning Objectives

Challenge #1

Challenge #2

Challenge #3

Your Challenge

Challenge #2:

Learning Objectives

Morse Code Encoder

Challenge #1:

Challenge #2: Morse Code Decoder

Challenge #3: Sending Light Signals

Solution...

Recursive Functions

Give this to Kevin: Recursive Function

Learning Objectives:

Challenge

Solution...

Learning Objectives

Python Script for The Twelve Days of Christmas:

Challenge:

Learning Objectives

CSS Box Model

Your Task

Learning Objectives

Your Task

Learning Objectives

Complete the code

Solution...

The code so far…

Solution...

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