String Manipulation

Posted on March 26, 2015 by Administrator Posted in Computer Science, Python - Intermediate, Python Challenges

typewriter

Learning Objectives

In this post we will focus on string manipulation techniques using five common techniques used in most procedural programming languages:

LEFT: to extract characters at the beginning of a string,

RIGHT: to extract characters at the end of a string,

LENGTH: to find out the number of characters in a string,

MID: to extract a set number of characters at a given position in a string,

LOCATE: to find if a substring is included in another string and if so return the position of this substring in the string.

LEFTRIGHTLENGTHMIDLOCATE

e.g. LEFT(myString, 5)

>>> to extract the first 5 characters of a string.

e.g. RIGHT(myString, 5)

>>> to extract the last 5 characters of a string.

e.g. LENGTH(myString)

>>> to retrieve the number of characters in a string.

e.g. MID(myString, 3, 5)

>>> to extract a set number of characters at a given position in a string.

e.g. LOCATE(“World”, “Hello World”)

>>> to find if a substring is included in another string and if so return the position of this substring in the string.
If the substring is not part of the string, the value -1 is returned.

Your Challenge

Check the code below which is based on the 5 string manipulation functions we mentioned above: Left, Right, Length, Mid, and Locate.

Your challenge is to tweak this code to ask the user to enter their school username in the following format:

Year Group Using two digits (e.g. “07” for year 7, “11” for year 11, “00” for staff members)
1 character for their initial (first letter of their firstname)
The user’s lastname
A 2-digit code: “_S” for students, “_T” for teachers, “_A” for admin staff.

For instance the following usernames are valid usernames:

07jFox_S
09kJohnson_S
11rTaylor_S
00pJones_T
00jOliver_A

Your program should read the username and decide:

If the username is less than 6 characters long the program should ask the user to enter a valid username.
If the username does not contain the character “_” it should also ask the user to enter a valid username.
If the username is valid, the program should decide if the user is a member of staff or a student.
If they are a student the programme should find out their year group.
The program should also display the initial of the student as well as their lastame.
Finally the program should display whether the user is a Student, a Teacher or an Admin member of staff.

HTML Codes

Posted on March 11, 2015 by Administrator Posted in HTML, CSS & JavaScript

When creating your webpages you may want to use sepcial characters. Using the the following codes in your HTML code:

Star Symbols
Symbol	HTML Code		Symbol	HTML Code
✢	4 Tear-drop asterisk	✢	✣	4 Balloon asterisk	✣
✥	Club asterisk	✥	✤	4 Balloon asterisk heavy	✤
✦	4-pointed star black	✦	✧	4-pointed star white	✧
✩	Stress outlined star	✩	✪	Circled white star	✪
✫	Open center black star	✫	✬	Black center white star	✬
✭	Black star outlined	✭	✮	Black star outlined heavy	✮
✯	Pinwheel star	✯	✰	White star shadowed	✰
✱	Asterisk heavy	✱	✲	Open center asterisk	✲
✳	8-spoked asterisk	✳	✴	8-pointed black star	✴
✵	8-pointed pinwheel star	✵	✶	6-pointed black star	✶
✷	8-p. rectilinear	✷	✸	8-p. rectilinear heavy	✸
✹	12-p. black star	✹	✺	16-p. asterisk	✺
✻	Teardrop-spoked ast.	✻	✼	Open center t-s. ast.	✼
✽	Heavy t-s. ast.	✽	✾	6-p. b&w florette	✾
✿	Black florette	✿	❀	White florette	❀
❁	8-p. outlined bl. florette	❁	❂	8-p. circled o.c. star	❂
❃	Heavy t-s. pinwheel	❃	❄	Snowflake	❄
❅	Tight 3foliate snowflake	❅	❆	Heavy chevron snowfl.	❆
❇	Sparkle	❇	❈	Heavy sparkle	❈
❉	Balloon asterisk	❉	❊	8 t-s. propeller asterisk	❊
❋	Heavy 8 t-s. propeller ast.	❋	❖	Bl. diamond w/ white X	❖
HTML Notes and Music Symbols
Symbol	HTML Code		Symbol	HTML Code
♩	quarter note	♩	♪	eighth note	♪
♫	two eighths	♫	♬	two sixteenths	♬
♭	flat note	♭	♮	natural note	♮
♯	sharp note	♯
Heart Symbols
Symbol	HTML Code		Symbol	HTML Code
❤	Heavy black heart	❤	❥	Heavy bl. heart rotated	❥
❦	Floral heart	❦	❧	Floral heart rotated	❧
❢	Heart exclamation mark	❢	❣	Heavy heart excl. mark	❣
♥	black heart	&hearts;	♡	red heart	♡
Utility Symbols
Symbol	HTML Code		Symbol	HTML Code
☎	telephone	☎	☏	telephone outline	☏
☐	check box empty	☐	☑	ballot box checked	☑
☒	ballot box with X	☒	✍	Sign here	✍
✓	Check mark	✓	✔	Check mark heavy	✔
✕	Multiplication X	✕	✖	Multiplication X heavy	✖
✗	Ballot X	✗	✘	Ballot X heavy	✘
•	Bullet	•	●	Password dot	●
✎	Pencil diagonal down	✎	✏	Pencil	✏
✐	Pencil diagonal up	✐
✁	Cut above	✁	✂	Cut here	✂
✃	Cut below	✃	✄	Scissors	✄
✆	Public pay phone	✆	✇	Film reel	✇
✈	Airport/airplane	✈	✉	Envelope/mail/email	✉
♲	Recycling	♲	♻	Recycling black	♻
@	At sign	@	⛽	Fuel Pump	⛽
Commercial Symbols
Symbol	HTML Code		Symbol	HTML Code
©	copyright	©	℠	Service Mark	&#8480
®	Registered trademark	®	™	Trademark	™
¤	Currency	¤	€	Euro	€
¢	Cent	¢	£	Pound	£
$	Dollar	&36;	¥	Yen	¥
§	Section	§	№	Number sign	№
Hands, Fingers and Faces
Symbol	HTML Code		Symbol	HTML Code
☚	Left-pointing	☚	☛	Right-pointing	☛
☜	Left-pointing	☜	☝	Upwards pointing	☝
☞	Right pointing	☞	☟	Downwards pointing	☟
✍	Sign here	✍	✌	victory sign	✌
☹	Frowning face	☹	☺	Smiley face	☺
☻	Black smiley face	☻
Science and Medical Symbols
Symbol	HTML Code		Symbol	HTML Code
℃	Celsius	℃	℉	Fahrenheit	℉
Ω	Ohm	Ω	℧	Inverted Ohm	℧
☠	Skull & Crossbones	☠	☡	Caution sign	☡
☢	Radioactive	☢	☣	Biohazard	☣
☤	Caduceus	☤	℞	Prescription	℞
Weather and Celestial Symbols
Symbol	HTML Code		Symbol	HTML Code
☀	Sunshine	☀	☁	Cloudy	☁
☂	Rain	☂	☃	Snow	☃
☄	Comet	☄	★	Star solid	★
☆	Star white	☆	☇	Lightning	☇
☈	Thunder	☈	☉	Sun	☉
☽	Waxing	☽	☾	Waning	☾
☼	Sunshine	☼
Religious and Spiritual Symbols
Symbol	HTML Code		Symbol	HTML Code
☥	Ankh	☥	☦	Eastern Christian Cross	☦
☧	Chi Rho Cross	☧	☨	Patriarchal Cross	☨
☩	Greek Cross	☩	✚	Greek Cross heavy	✚
✙	Greek Cross outline	✙	☓	Saltire, St.Andrew’s Cross	☓
✝	Latin Roman Cross	✝	✞	Latin Cross 3D shadow	✞
✟	Latin Cross outline	✟	☮	Peace sign	☮
✠	Maltese Cross	✠	✡	Star of David	✡
☪	Crescent Moon & Star	☪	☫	Farsi symbol	☫
☬	Adi Shakti	☬	☭	Hammer & Sickle	☭
☯	Yin & Yang	☯	☸	Dharma Wheel	☸
☰	Trigram Heaven	☰	☱	Trigram Lake	☱
☲	Trigram Fire	☲	☳	Trigram Thunder	☳
☴	Trigram Wind	☴	☵	Trigram Water	☵
☶	Trigram Mountain	☶	☷	Trigram Heaven	☷
HTML Zodiac Signs
Symbol	HTML Code		Symbol	HTML Code
♈	Aries	♈	♉	Taurus	♉
♊	Gemini	♊	♋	Cancer	♋
♌	Leo	♌	♍	Virgo	♍
♎	Libra	♎	♏	Scorpio	♏
♐	Sagitarius	♐	♑	Capricorn	♑
♒	Aquarius	♒	♓	Pisces	♓
HTML Planetary Symbols
Symbol	HTML Code		Symbol	HTML Code
☿	Mercury	☿	♀	Venus	♀
♁	Earth	♁	♂	Mars	♂
♃	Jupiter	♃	♄	Saturn	♄
♅	Uranus	♅	♆	Neptune	♆
♇	Pluto	♇
HTML Chess Symbols
Symbol	HTML Code		Symbol	HTML Code
♔	White King	♔	♕	White Queen	♕
♖	White Rook	♖	♗	White Bishop	♗
♘	White Knight	♘	♙	White Pawn	♙
♚	Black King	♚	♛	Black Queen	♛
♜	Black Rook	♜	♝	Black Bishop	♝
♞	Black Knight	♞	♟	Black Pawn	♟
HTML Card Symbols
Symbol	HTML Code		Symbol	HTML Code
♠	black spade	&spades;	♤	red spade	♤
♥	black heart	&hearts;	♡	red heart	♡
♦	black diamond	&diams;	♢	red diamond	♢
♣	black club	&clubs;	♧	red club	♧

My Weather Forecast

Posted on March 11, 2015 by Administrator Posted in Computer Science, Python - Beginner, Python Challenges

Learning Objectives

In this challenge we are going to use selection blocks to display a weather forecast report.

Selection blocks uses if, elif and else statements to decide which block of code to run.

if statements use comparison operators to compare values and make a decision based on the comparison.

The main comparison operators are:

Comparison Operator	Meaning	Example
==	is equal to	4==4
!=	is different from	4!=7
<	is lower than	3<5
>	is greater than	9>2
<=	is lower or equal to	3<=5 5<=5
>=	is greater or equal to	9>=2 5>=5

When using comparison operators the result of a comparison is either true or false. For instance:

3 < 5 returns true,
3 > 5 returns false.

It is also possible to combine comparisons together using boolean operators such as and and or. This enables to check if more than one comparison are true (and operator) or whether at least one of the comparisons is true (or operator). e.g.

(3 < 5) and (3 < 7) returns true,
(3 == 5) or (3 < 9) returns true,
(3 == 5) and (3 < 9) returns false.

Check the code

Check the following code and notice how it is using:

Selection structures (using if statements),
Comparison operators (<, <=, >, >=, !=, ==)
Boolean logic (AND, OR) when using comparison operators within if statements

Task #1: Tweak the code

Your challenge consists of adding more to this weather report.
The same way this report randomly finds out if today will be sunny or rainy, add some code to find out whether it will be icy and whether it will be snowy.

If the weather is icy then display a message saying: “Be careful not to fall over on black ice.”

If the weather is either icy or snowy then display a message saying: “Put your gloves on, it’s going to be cold today.”

Task #2:

Add a criteria to find out whether it will be windy or not.

If the weather is both sunny and windy write a message saying: “It’s a good time to go sailing!”

If the weather is sunny but not windy write a message saying: “A perfect day to go to the beach!”

Task #3:

Add your own criteria and messages to complete this weather forecast report further.

Tagged with: Python Challenge, Selection

Year 2050

Posted on March 11, 2015 by Administrator Posted in Computer Science, Python - Beginner, Python Challenges, Solved Challenges

Have you got any idea how old you will be in 2050?

By completing the following challenges we will write computer algorithms for the computer to tell us more about our age in the future!

Getting Started

First you will need to copy the following code in your Python IDE or using an online Python editor.

thisYear = 2015 
print("We are in " + str(thisYear))
age = int(input("How old are you?"))
print("You are " + str(age) + " years old.")

Challenge #1: How old will you be in…

ChallengeSolution

Complete the above code with a for loop to display the following messages:

In 2016 you will be … years old.
In 2017 you will be … years old.
…
In 2050 you will be … years old.

thisYear = 2015 
print("We are in " + str(thisYear))
age = int(input("How old are you?"))
print("You are " + str(age) + " years old.")

for i in range(0,36):
  thisYear += 1
  age += 1
  print("In " + str(thisYear) + " you will be " + str(age) + " years old.")

Challenge #2: How old will you be in 2050 (without using a loop).

ChallengeSolution

Complete the above code without using a for loop to display the following message:

In 2050 you will be … years old.

thisYear = 2015 
print("We are in " + str(thisYear))
age = int(input("How old are you?"))
print("You are " + str(age) + " years old.")

yearsDifference = 2050 - thisYear
age = age + yearsDifference
print("In 2050 you will be " + str(age) + " years old.")

Challenge #3: When were your born?

ChallengeSolution

Tweak your code so that the Python program calculates and displays the year you were born. For instance it will display:

You were born in ….

thisYear = 2015 
print("We are in " + str(thisYear))
age = int(input("How old are you?"))
print("You are " + str(age) + " years old.")

birthYear = thisYear - age
print("You were born in " + str(birthYear) + ".")

Challenge #4: In how many years will you turn 21!

ChallengeSolution

Tweak your code so that the Python program calculates and displays how many years till your turn 21. Note that if the end-user is older than 21, then the program should tell them how many years have passed since their 21st birthday.

thisYear = 2015 
print("We are in " + str(thisYear))
age = int(input("How old are you?"))
print("You are " + str(age) + " years old.")

if age<21:
  yearsDifference = 21 - age
  print("You will be 21 in " + str(yearsDifference) + " years.")
elif age==21:
  print("You are 21 years old this year!")
elif age>21:
  yearsDifference = age - 21
  print("You were 21 years old " + str(yearsDifference) + " years ago.")

Extension

In all the challenges listed above we hardcoded the current year to 2015. This means that our programs will not work next year unless we change the code on line 1: from thisYear = 2015 to thisYear = 2016.

Instead we can improve our code by getting Python to find out what year we are currently in.

The following lines of code show you how to achieve this. You can reuse them to tweak your code.

Solution...

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

Tagged with: Date and Time, iteration, Python Challenge

Resistor Value Calculator

Posted on March 11, 2015 by Administrator Posted in Computer Science, HTML, CSS & JavaScript, JavaScript, Python - Intermediate, Python Challenges, Solved Challenges

When designing electronic circuits you may need to use resistors. Each resistor has a resistance value expressed in ohms (Ω). Resistors are identified by a series of concentric coloured bands. Each band colour has a value which is used to calculate the resistance value of the resistor.

Here is how the resistor colour code works:

You can check the resistance value of a resistor online using an online calculator.

Your Challenge

Your challenge consists of writing a program that asks the user to enter three colours (e.g. Red, Red, Green) and returns the resistance value (e.g. 2,200,000 Ω or 2,200 kΩ).

Test your code

Test your code to find the resistance value of the following three resistors:

Challenge #2: The other way round

Create a computer program that asks the user for a resistor value in ohms and returns the three colours matching this value.

Solution...

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

Tagged with: JavaScript, Python

Meet E.V.E.

Posted on March 10, 2015 by Administrator Posted in Computer Science, Python - Beginner, Python Challenges, Solved Challenges

Meet E.V.E., a computer algorithm with artificial intelligence. E.V.E. can communicate with human beings. Well it’s only a start and we need you to complete the code provided below for E.V.E to be able to communicate more effectively with teenagers.

Learning Objectives

By completing this programming challenge you will learn how to code in Python. You will use the input() method to ask questions to the end user. You will store their answers using your own variables. You will use if statements to check the user answers and the print() method to write information on the screen.

Your Challenge

Complete the code below to let E.V.E. ask more questions to the end-user.

Solution...

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

Tagged with: Python, Selection

Optical Illusions

Posted on March 10, 2015 by Administrator Posted in Computer Science, Python - Beginner, Python Challenges

Which of the above two purple circles is bigger?

Learning Objectives

In this challenge you will use Python Turtle to draw geometric shapes and optical illusions.

To help you we have created three functions as follows:

drawLine() to draw a straight lines between two points,
drawSquare() to draw a square of a given size and colour,
drawCircle() to draw a circle of a given size and colour.

To position these shapes on the screen you will need to use x,y coordinates and pass these coordinates when using the three functions given above.

(X,Y) Coordinates

The canvas we are drawing on (using Python Turtle) is 400 pixels wide by 400 pixels high.
Look at the canvas below to understand how (x,y) coordinates work:

Check the code

Your Challenge

Complete the code given to draw the following optical illusions:

Which of the above two purple circles is bigger?

Which of the above two lines is longer?

Are both purple lines perfectly straight?

Are all the white dots really white?

Tagged with: Coordinates, Python Turtle

All Stars Football Team

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

In this challenge we are looking at how a list can be used to store all the players’ names of a football team.

Using a set of functions we then manipulate this list to:

Find a value in a list and change it to something else. We use this to perform a substitution: replace a player with another player.

Find a value in a list and remove it from the list. We will use this to issue a red card and hence remove a player from the team.

When using our functions we will pass some parameters such as the name of the players we want to substitute or the name of the player receiving a red card.

To make the code easier to follow we created a football.py file that contains three functions:

displaySquad()
substituePlayer()
redCard()

Our main program first initialises the team as a list of 11 players called allStars.

Then we use the substituePlayer function and redCard function to change the composition of the team.

Finally we use the displaySquad function to display the full team at the end of the game.

Check the code

Your Challenge

Tweak this code to change the composition of the allStars team using your favourite selection of 11 players.

Perform some substitutions and issue a few red cards to see how it will affect your team.

Tagged with: Function, List, Procedure, Python, subroutine

Download Python

Posted on March 8, 2015 by Administrator Posted in Computer Science, Free Downloads, Python Challenges

Before installing Python check our recommendations at the bottom of this page!

Ready to complete some of these Python challenges at home? Then you will need to download Python 3 which is completely free to download: https://www.python.org/downloads/.

We also recommend you to install a Python IDE such as PyScripter which is also free to download: https://code.google.com/p/pyscripter/. It makes coding and debugging a lot easier.

Our Recommendations

To avoid any incompatibility issues, for Windows users we recommend you to install the following versions of Python, PyScripter and Pygame:

Python	version 3.9	Download (Source: https://www.python.org/downloads/windows/	More recent versions may not be fully compatible with our recommended versions PyScripter / Pygame
PyScripter	Version 2.6	https://sourceforge.net/projects/pyscripter/
Pygame	version 1.9.2a0 for Windows 32 bit – Python 3.3	Download (Source: https://bitbucket.org/pygame/pygame/downloads)

Should you not have the above versions, we would recommend uninstalling Python / PyScripter and Pygame to install the recommended versions instead.

Python Online

Should you decide not to install Python on your computer, you can still use online coding environments such as Trinket.io or CodingGround:

Tagged with: download, installation, pigame, PyScripter, Python

Lottery Numbers

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

In this challenge we are going to write a Python program that automatically generates six random numbers (from 1 to 50) and display them on the screen, sorted in ascending order.

The program will need to make sure that each number is unique; the same number cannot come twice in the selection of six selected numbers.

Learning Objectives

By completing this code, you will understand the difference between the two types of loops used in Python:

For Loops (Count-Controlled Loops): A count-controlled loop is one that is executed a certain number of times. In our example, because we know that we need exactly six numbers we are going to use a for loop to repeat (iterate through) some of our code exactly six times.
While Loops (Condition-Controlled Loops): A condition-controlled loop such as a While loop keeps going while a certain condition is true. As soon as the condition becomes false, the loop stops iterating. In our case, when generating a random number, we are going the check that the new number has not already been picked up. If it has then we are going to generate a new one and will carry on doing so till we get a number that has not already been picked up.

Check the code

Your Challenge

Complete this code to store your own selection of six numbers. For testing purposes, you can store these numbers directly into the code and display these to the end-user. Alternatively you can ask the end-user to type six numbers.
Then your code will use the program given above to generate the six lottery numbers.
Finally your code will check and inform the end-user of how many numbers the user guessed correctly by comparing the user’s six numbers with the six randomly generated lottery numbers!

Note

The probability of guessing several lottery numbers is very low. You may want to tweak your program to only pick up numbers between 1 and 20 (instead of 50). This will give you a better chance to guess some of these numbers and hence test whether your code is working.

Video Tutorial

Solution...

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

Tagged with: iteration, List, Python Challenge

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Your Challenge

Star Symbols

HTML Notes and Music Symbols

Heart Symbols

Utility Symbols

Commercial Symbols

Hands, Fingers and Faces

Science and Medical Symbols

Weather and Celestial Symbols

Religious and Spiritual Symbols

HTML Zodiac Signs

HTML Planetary Symbols

HTML Chess Symbols

HTML Card Symbols

Learning Objectives

Check the code

Task #1: Tweak the code

Task #2:

Task #3:

Getting Started

Challenge #1: How old will you be in…

Challenge #2: How old will you be in 2050 (without using a loop).

Challenge #3: When were your born?

Challenge #4: In how many years will you turn 21!

Extension

Solution...

Your Challenge

Test your code

Challenge #2: The other way round

Solution...

Learning Objectives

Your Challenge

Solution...

Learning Objectives

(X,Y) Coordinates

Check the code

Your Challenge

Check the code

Your Challenge

Our Recommendations

Python Online

Learning Objectives

Check the code

Your Challenge

Note

Video Tutorial

Solution...

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