Making a list
So far we’ve talked about numbers, strings and Booleans where each variable just stores one thing at a time. What happens if we want to manage a shopping list, or a list of students in my class… and I want to be able to manage that entire list of things together? Python allows us to create lists!
Here are three lists:
primes = [1, 2, 3, 5, 7, 11, 13, 17, 19, 23] vowels = ["A", "E", "I", "O", "U"] starwars = ["Luke", "Han", "Leah", "Obi-wan", "Yoda", "Rey", "Finn"]
The two key tips to making a list: Python knows it is a list because of the square brackets! Items in a list are separated by commas!
Try the following to work out how the various commands behave.
print( len( starwars ) ) print( starwars ) print( starwars ) print( starwars ) print( starwars[-1] ) print( starwars )
After doing the above, can you guess what this will do?
starwars.append("Darth Vader") print( len( starwars )) print( starwars[-1] ) print( starwars )
We can also use the “in” comparison test we used for strings
print( "r2d2" in starwars )
What command would make that print True?
What would these do?
print( starwars[0:2] ) print( starwars[1:3] ) print( starwars[:3] ) print( starwars[3:] )
How will this behave?
starwars.sort() print( starwars )
Other tricks that are useful when we have lists of numbers:
minimum = min(primes) maximum = max(primes) print("The minimum was ",minimum," and the maximum was ",maximum)