Python for Beginners Start to Code with Python write code

Python uses indentation and how it works is that the indentation indicates a block of code. In Python indentation is very important.

Commenting in Python Code

Comments can explain code, making it more readable and also great for testing when you want lines of code not to execute. You can also provide information that can be used later and referred to at a later date by yourself or other developers.

Variables -

One of the most important concepts of programming. Variables are at the core of programming. They are containers that can hold information, which can then be easily referenced within the code and returned when needed. Think of a variable as a way to reference something that might change, like a box where you can put items into it and return back the contents of that box by selecting the box label.

• Strings can be single or double quote

• Variable names are case-sensitive

Rules -

1. Must start with letter or _ underscore

2. Can use a-zA-Z0-9_ alpha numeric characters within the variable name

3. Case sensitive

4. Use Camel case to indicate words in variable name

Get type of data

type(“variable”)

How to assign multiple values in variables by comma separation of variable names and assigning to comma separated values. Comma separate for multiple variables in one line

You can also assign the same value to all variable names using the = sign

Using a collection you can assign those values to a number of variables within one statement

Python Data Types

More Data type within Python

Boolean can be either True or False - must be capitalized

Variables can also store multiple items in various collections.

Four built in data types to store multiple items are Tuple, Set, List and Dictionary.

Python List

Lists - created with square brackets testList = [50,"100",True,50,"50"]

• have defined order and the order does not change when in the list

• You can add new items and remove items from the list. The list can be changed

• Duplicate values are allowed within the list.

• Use index value to identify and retrieve values from within the List. Indexes are zero based, values start at zero.

• Use the len() function to determine the number of items within the list.

Get Values -

tempList = [“one”,”two”,”three”,”four”]]

Use the index value example 1 to return the value in a list.

tempList[1] will return “two”

tempList[1] = “NEW” - will assign a new value of NEW to index item 1

tempList[-1] will return “four” last item in the list

tempList[2:3] will return ,”three”,”four”] - if no end value is provided will return all the items until the end.

tempList[:3] will return all expect the item with index 3

tempList.index(“two”) - gets the index value of the item

check if in list print("two" in testList) will return a boolean result

tempList.append(“last”)

tempList.insert(1,“last”)

tempList.remove(“last”)

tempList.pop(1) no index removes the last item in the list

del tempList[0]

del tempList - removes the entire list

tempList.clear() - empties list

tempList.sort() list sorts ascending and alphanumerically - change sort order .sort(reverse = True)

copyList = tempList.copy()

Python Tuple

Tuple - created using rounded brackets testTuple = (50,"100",True,50,"50")

• Does allow duplicates since just like lists they are indexed.

• ordered is defined and does not change

• cannot change or remove items from the tuple after it's created

• Zero based and can use functions like len() to get the number of items

• Allowed data types are strings, integers, and booleans

Get Values -

Using the index just like lists.

Python Set

Sets - created using curly brackets testSet = {50,"100",True,50,"50",50,100,100,"a"}

• no order they are unordered. They have no set order that they appear in.

• values cannot be changed after its set although you can add to it and remove from it

• Allowed data types are strings, integers, and booleans

Get Values

check if it exists using (“value” in testSet )

testSet.add(“Last”)

testSet.remove(“Last”)

testSet.pop() removes random item

Dictionary - named key value pairs using curly brackets testDic = {"first":50,"second":"100","third":True,"a":50,"a":"LAST"}

• order does not change as they are not indexed and accessed using the key value

• Can be changed and updated as needed referencing the key value. Add and remove new items into the dictionary

• Cannot have more than one item using the key name

• Dictionaries can contain nested dictionaries in a child parent format

Get Values

testDic[“first”] or to change use testDic[“first”]=

testDic.keys() - gets all the keys

testDic[“newKey”] = “to add new items”

testDic.pop(“first”) to remove items

testDic.clear to clear all items

Get User Input in terminal assign to a Variable

Within your code you can request the user provide an input. The input will be a string data type by default. You can assign the response of the user input to a variable that can be used within your code.

String methods can be helpful in checking to see if they can be converted to an integer.

You can use a condition to check and run a block of code depending on the boolean value of a variable.

The isnumeric() method returns True if all the characters in the string value are numeric (0-9), otherwise it will return a value of False.

Exercise Create a simple Calculator

Using the input, ask the user for two numbers, take the numbers and convert them to integers so that you can add them together. Create an output message to the user with the total and the equation for the two numbers added together.

Conditions and Logic If .. Else Statements

Conditions allow us to apply logic into our Python code.

Indentation is important as it help Python understand the block of code that needs to run if the condition is true.

Exploring shorthand methods that can be written in one statement

Bouncer Exercise Project - Code bouncer allowed in or not?

Create an application that will ask the user their age. Depending on the age, first check if the response is a number. If its not a number reject them and provide a message back. If its a number then check to see if the value is allowed in and can drink which is 21+, if they are 18-20 they can come in but not drink and lastly if they are 17 or less they should not be allowed in. Create the application to follow these rules!

Loops while loop

While loop allows us to run blocks of code multiple times. There are options using the keyword continue to skip an iteration as well as using the keyboard break to leave and stop the loop. In addition to the loop there is also an option to provide an alternative output once the loop condition is no longer true and run an else block of code.

For Loop for lists and dictionary items

Using a for loop can output the contents of a list or a dictionary.

Exercise Number Guessing Game

Using a while loop create a game that allows the user to make a guess at the hidden value of a number.

1. Start off create secret number in a variable

2. Set a variable that will limit the number of guesses

3. Create a variable to hold the number of guesses made by the user.

4. Setup a while loop that compares guess value to the secret number

5. Print provide the user how many guesses they have left

6. Capture the input from the users guess as a integer

7. If the users guess is correct set the final message as a WIN

8. Provide feedback to the user if their guess incorrect guess was too high or too low

9. Increment the counter and check if the count is at the max guesses, if it is break from the while loop

10. Output the WIN or LOSE message to the player

Functions core part of programming

You can reuse blocks of code invoking them anytime within the code to run the function block of code. Function can have arguments that are values passed and assigned to the variable names used within the function arguments. These values can then be used within the function. You can also return values with functions, those values can then be assigned to variables and used within your Python Code.

Lambda

Shorter anonymous functions written as one statement

Function scope

Values can be accessed locally with the block of code that is assigning the values. Each block of code has its own scope, the main block of code is called the global scope. You can use variables from the parent block scope but you cannot update the variable values within the child scope. There are keywords to access and update the global scope, you can use global to reference the variable you want to use. That opens the variable up to be updated within the child scope. You can also use the keyword nonlocal to access the parent scope variables to update them within a child local scope.

Python built in Methods

Built in functions within Python

Python Modules

You can use functions and data from other python files in your main file. Allows you to import functionality referencing the module

Import Modules Python

datetime is a stand module that you can use to get date values

String Functions Python

We can update and manipulate the string values with useful built in string methods that can be applied to strings

Projects with Python

Create a countdown timer

1. create a function that will decrease a val

2. Using Modulus and Floor Division calculate the minutes and seconds

3. Create a string output value using format to structure it as minutes and seconds

4. Using the time module import the sleep method slowing the output with a 1 second delay

5. Subtract from the total seconds

6. Once the while loop completes print the time is up and invoke the start function again

7. Create a starting function that gets the users inputs for the countdown timer in total seconds. Check if the input is numeric if it is send the total second value to the countdown function

Dice game in Python

Play against the computer, role the dice get a random value and see who scores more. The highest role wins the game. Perfect game to practice and learn more about using random in game logic, and applying conditions to check for a winner

1. Import the random module

2. setup default variables for score and set the values of the roles from min to max.

3. Create a function to house the game coding

4. Setup a while loop that will run the block of game code

5. Game code generates random values for both the player and computer.

6. Apply conditions to check who wins

7. output the feedback and results to the player. Keeping score of the rounds.

8. Allow player to exit and end game

Rock Paper Scissors Python coding Game

Rock paper scissors, played between the player and the computer. Setup the game make a selection and see who wins. Rock beats Scissors and crushes them, Paper covers the rock and wins, Scissors can cut up the paper to win.

1. import the random module

2. setup the default values and array

3. create the gameplay function

4. create a loop within the gameplay function

5. Get the user selection and generate a random selection for the computer

6. Apply logic to see who wins

7. Let the player exit the game or go for another round.