How To Create A Shopping List In Python

Create a list in Python
Access an item or items in a list
Loop through a Python List
Check if an item exists in a list
Get the length of a Python List.
Sort a Python List
Reverse sort items in a Python List
Add a single item to a Python List
Add multiple items to a Python List
Add an item to a Python List at a specific Location
Remove an item from a Python List by index using pop()
Remove an item from a Python List by index using del keyword
Remove an item from a Python List by value
Remove all items from a Python List (empty a list)

Features of a List

A list is a collection of objects. It contains the following features:

It is ordered
It is changeable
It allows duplicate members

Create a list in Python

          #Lists are written with square brackets shoppinglist = ["milk","bread","apples","eggs","rice"] print(shoppinglist)

Access an item or items in a list

Lists are start at position 0. You can use slice notation like we covered in the strings chapter

          #Create a list shoppinglist = ["milk","bread","apples","eggs","rice"] #print the first item in the list print(shoppinglist[0]) #print the last item in the list print(shoppinglist[-1]) #print items starting at position 2 and ending before position 4 print(shoppinglist[2:4])

Loop through a Python List

You can use a for loop to iterate through a list.

          shoppinglist = ["milk","bread","apples","eggs","rice"] for x in shoppinglist:     print(x)

Check if an item exists in a list

Use the "in" keyword to check if an item exists in a list.

          shoppinglist = ["milk","bread","apples","eggs","rice"] if "milk" in shoppinglist:     print("milk is in your shopping list")

Get the length of a Python List.

Use the len() method to get the length of a list

          shoppinglist = ["milk","bread","apples","eggs","rice"] print(len(shoppinglist)

Sort a Python List

Use the sort() method to sort a list.

          shoppinglist = ["milk","bread","apples","eggs","rice"] shoppinglist.sort() print(shoppinglist)

Reverse sort items in a Python List

Use the reverse() method to reverse sort a list.

          shoppinglist = ["milk","bread","apples","eggs","rice"] shoppinglist.reverse() print(shoppinglist)

Add a single item to a Python List

Add a single item to a Python list using the append() method.

          shoppinglist = ["milk","bread","apples","eggs","rice"] #add cookies to the list using append shoppinglist.append("cookies") print(shoppinglist)

Add multiple items to a Python List

Add multiple items to a Python List using the extends() method.

          #Use extend to add a collection to a list proteinlist = ["steak","chicken","fish"] shoppinglist.extend(proteinlist) print("using extend") print(shoppinglist)

Add an item to a Python List at a specific Location

To add an item to a list at a specific location use the insert() method.

          #Use extend to add a collection to a list shoppinglist = ["steak","chicken","fish"] shoppinglist.insert(1,"detergent") print("using insert") print(shoppinglist)

Remove an item from a Python List by index using pop()

To remove an item from a Python List by index use the pop() method.

          shoppinglist = ["milk","bread","apples","eggs","rice"] #Use pop to remove an item by index print("use pop") shoppinglist.pop(0) print(shoppinglist)

Remove an item from a Python List by index using del keyword

To remove an item from a Python List by index use the del keyword.

          shoppinglist = ["milk","bread","apples","eggs","rice"] print("use delete") del shoppinglist[0] print(shoppinglist)

Remove an item from a Python List by value

To remove an item from a Python List by value use the remove() method.

          shoppinglist = ["milk","bread","apples","eggs","rice"] print("use remove") shoppinglist.remove("bread") print(shoppinglist)

Remove all items from a Python List (empty a list)

To remove all items from a Python List use the clear() method.

          print("use clear") shoppinglist = ["milk","bread","apples","eggs","rice"] shoppinglist.clear() print(shoppinglist)

Python Lesson 1: Hello World in Python
Python Lesson 2: Reserved Keywords
Python Lesson 3: Creating Variables
Python Lesson 4: Performing math calculations in Python using operators
Python Lesson 5: Working with Strings
Python Lesson 6: Useful String Methods
Python Lesson 7: Getting User Keyboard input
Python Lesson 8: Importing Modules into your Python code
Python Lesson 9: Decision making in Python
Python Lesson 10: Creating loops in Python
Python Lesson 11: Lists in Python
Python Lesson 12: Tuples in Python
Python Lesson 13: Dictionaries in Python
Python Lesson 14: Sets in Python
Python Lesson 15: Dealing with dates and time
Python Lesson 16: Creating and using functions
Python Lesson 17: Creating and using classes in Python
Python Lesson 18: List Comprehensions
Python Lesson 19: Lambda Functions
Python Lesson 20: Error Handling