1. Computing Subject Knowledge Enhancement Python

2. SESSION OUTLINE Audit of your current position Practical Investigation GCSE Controlled Assessment Q&A

3. AUDIT Please complete the following audit Audit

4. PYTHON 2 or 3 Python has two versions which are commonly used. St James’ currently use Python 2.7.8 because; –It has more support for the libraries available –It is the version the Universities I visited used –It was the final and most stable version from Python 2

5. WHAT WE ARE COVERING From the results of your audit I am going to cover the following sections; –IDLE and how to use it –Basic Python Syntax –Data Types and Variables –Additional Modules –For and While Loops –List and Dictionaries

6. IDLE IDLE is the application we use to develop Python programs. IDEL is; –Free to download –Easy to install as it requires no additional permissions and does not make an executable –Provides some syntax highlighting and error handling –Interactive and script modes

7. THE BASICS When coding in Python for the first time you need to know a few important things; –Syntax Red = Comments Green = String Black = Normal Text Builtin Functions = Purple Key Words = Orange

8. THE BASICS In addition to syntax highlighting; –Python offers object help using the tab key –Python is a little forgiving when using variables –Script mode can be executed on the fly pressing F5 or by running the.py file

9. DATA TYPES There are many different data types available but the three which we are going to use are; –Strings – Also known as text and must be placed within a set of speech marks e.g. “I am a string” –Integers - Also known as whole numbers between -2,147,483,648 and 2,147,483,647 –Floats - Also known as real numbers which include decimal places e.g. 19.99

10. DATA TYPES A few rules that you need to be aware of when trying to manipulate data; –“A” + “A” = “AA” –“A” + 1 = ERROR –“A” * 2 = “AA” –2 * 2 = 4

11. VARIABLES In all of the programming languages you have used, variables have played a really important role. This is because; –A variable can store any type of data –A variable can change the value of the data it stores –A variable has to be given a useful name –A variable allow your program to remember specific things studentName = “Dave” studentAge = 14

12. PYTHON VARIABLES What makes Python good for first time coders is; –Variables don’t need to be declared Dim interestRate As Integer (VB) Int InterestRate (JAVA) –Python allows you to name a variable and just use it regardless of the type of data

13. LESSON NUMBER 1 The most important lesson that new coders need to learn is; GETTING IT WRONG = GETTING IT RIGHT

14. NAME AND AGE Produce a simple program which can do the following; –Store your own first name (name) –Store your own age (age) –Print out a your name and age e.g. Dave is 48

15. CODE SNIPPETS Even the most experience of programmers need to use the internet to gain code snippets; –Site 1Site 1 –Site 2Site 2 –Site 3Site 3 –Site 4 (MOST USEFUL)Site 4

16. A DIFFERENT WAY Another way I give learners coding challenge is to; –Give a part complete program with comments –A complete program with errors –An entire challenge coded in pairs

17. INPUT vs RAW_INPUT Gathering user input is always on GCSE controlled assessment and this can be done two ways in Python; INPUTRAW_INPUT Gives a customized message Can detect data type based on syntaxAlways stores value as string Can produce error based upon inputRequires type conversion/cast Input(“Enter a phone number”)Raw_input(“Enter new cost”)

18. HOW TO CONVERT/CAST To convert a value or variable from one data type to another you need to use a range of functions; –Str() function will convert any value or variable into a string The str() function requires a single argument, this goes within the parentheses () The argument is the value or variable that you want to change e.g. str(10.99) or str(phoneNumber) –To convert to integers you use int() and to convert to a float you use float()

19. NAME AND AGE ENHANCED Enhance your name and age program so that; –Ask the user to enter their name (name) –Ask the user t o enter their age(age) –Print out a the name and age e.g. Dave is 48

20. VAT PROBLEM You must now produce a solution to the following problem –Stores the value of VAT in a variable –Asks the user to enter the COST of the product –Calculates the COST + VAT –prints() out a message plus the TOTAL

21. POSSIBLE SOLUTION A solution of the problem could something like the following;

22. IMPORT MODULES One useful thing within programing languages are modules; –Use the key word import –Import your module at the very start of your program using the module name –To access the modules specific operations use the name of the module followed by a full stop and the operation

23. USEFUL MODULES Here is a list of useful modules which you may need to use at some point or you may want to experiment with; Random – number focused module PyGame – GUI tools for games TkInter – GUI tools for any type of program Math – simple math focused module Decimal – exactly what it states, decimal numbers Datetime – as above, focused on date and times Time – as above but just time focused Re – useful for checking a range of operations on strings Pickle – used for storing values in external files Operator – specific operations e.g. add(a,b) instead of a + b

24. FOR LOOP If you consider doing something over and over again, this is technically called a loop. When something gets repeated;

25. FOR LOOP STEPS The for loop consists of the following steps; –For – This tells your program that you are about to perform a loop –Variable e.g. counter – This will store how many times the loop has occurrd, allowing the loop to know when it has reached its target –Range – This specifies how many times the loop should occur, important note here, if we did 1-5 the loop would only occur 4 times as we say loop 1, 2, 3, 4 and stop before 5. –Repeat statement(s) – This is the statements that will be repeated until the loop reaches the target number

26. FOR LOOP PRACTICE You are now going to practice the following programs; –Repeat the statement “I can use a for loop correctly” 3 times –Repeat “I have been looped” 5 times plus the value of the counter variable

27. WHILE LOOP Similar to a for loop is a while loop, these both can do the same job but a for loop repeats a specific amount of times, a while loop repeats until a condition has been met.

28. WHILE LOOP STEPS The while loop consists of the following steps; –Variable(s) declared and values assigned – This will be the section which stores a value that a while loop will check –While – This will check if a condition is true, while this condition is true the statements below will run –Statement(s) – Below the while condition check are the statements which will be performed whilst the condition is true

29. WHILE LOOP PRACTICE You are now going to practice the following programs; –Countdown from 50 and show the current number you are on –Count up to 50 and show the current number you are on

30. PROBLEM Produce a program that will check if variable (password) matches the string entered by a user. Until the password and the guess match, show an error message but if they do match show a message that tells the user this. –password equals a specific value –While true –Ask a user to enter a guess and store this in a variable –If the guess equals the password show a message and break –Else show an error message

31. SOLUTION

32. GUESS THE NUMBER DESIGN You must now produce a quick design in pairs, this design must be in Pseudo Code or in a flow diagram. Consider the following; –What does the program need to do overall –What values does the program need to store –How does the program know if the use guessed correct or incorrect –How does the program know when to finish or loop over again and allow the user to guess again

33. PSEUDO CODE Your design in Pseudo code should look something like the following; Import random number = random.randint(0,10) while True Guess = Ask user to guess number If Guess equal to Number You guessed correctly End loop else You guessed incorrectly

34. SOLUTION

35. EBI How could you make your guess the number program even better? –Tell the user if the number they guessed was too low –Tell the user if the number they guessed was too high –Let the user pick the range of numbers that the random number can be generated from –Keep count of how many times the user has guessed

36. SOLUTION

37. LISTS IN PYTHON A list is a type of variable that can store more than one item. I would describe the characteristics of a list as; –A variable that uses brackets [ ] –A variable that can store more than one value –A variable that stores the values in a number list –The list always starts at position zero and not 1

38. LIST METHODS shoppingList = [“Bread”, “Milk”, “Jam”] –This will add three values to single variable, also known as a list print(shoppingList[0]) –This will print the first item in the shoppingList, that should be Bread print(shoppingList[1:3]) –This will print the items in the range of position 1 and 2 only shoppingList[0] = “Brown Bread” –This will change/overwrite the value stored in position 0 from Bread to Brown Bread

39. LIST METHODS shoppingList.append(“Rice Pudding”) –This will add the value Rice Pudding to the end of the list, position 3 Del shoppingList[0] –If I buy the Brown Bread and want to remove it from my list I can do using the above statement, this statement only allows you to remove by position shoppingList.remove(“Brown Bread”) –This will do a very similar job to above but will delete by the value and not position of an item in the list shoppingList.sort() –This will sort the items in the shopping list into ascending order e.g. A-Z or lowest to highest

40. DICTIONARIES A dictionary is type of variable and very similar to a list but it has two very important differences; –We use Braces { and Brackets [ like we did in a list –A dictionary contains a key and value, the key is the item we can search for and the value will be shown KeyValue 2010001Dave Smith 2010002Kirsty Graham 2010003Daniel Taylor

41. DICTIONARY METHODS users = {“2010001” : “Dave Smith”, “2010002” : “Kirsty Graham”} –This will produce a dictionary called users –The dictionary will store two items –The keys for the items are 2010001 and 2010002 –The values for the keys are “Dave Smith” and “Kirsty Graham” –Two add an entry you use a a key and value with a colon showing the separation; –“I am the key” : “I am the value of the key” print(users[“2010001”]) –This will search for the key within the dictionary and print out the value, this should be Dave Smith from the above entries del users[“2010001”] –This will delete Dave Smith from the dictionary

42. Users[“2010002”] = “Helen Baxter” –This will update/overwrite the value stored for the key 2010002, so Kirsty Graham will change to Helen Baxter Users.get(“2010002”) –This will get the value for the key 2010002, this should now be Helen Baxter Users[“2010004”] = “John Wilson” –This will add John Wilson to the dictionary with the key 2010004 DICTIONARY METHODS

43. TASK Your task is to complete an address book or contacts list as you may know it. The contacts list must do the following; –Show a list of options for the user to select, the list should be; 1.To add a new contact 2.To see the phone number of a contact 3.To update the number of a contact 4.To remove a contact –You may need to make use of; A python dictionary A range of variables A set of IF, ELIF and ELSE statements

44. Q&A ?

45. Thank You Email: pearcem@st-james.bolton.sch.uk Tel: 01204 333 000 Twitter: @TheRealMrPearce