Lesson 05-01: Python Lists

Learning Target: I can utilize python lists to hold various data.
Learning Target: I can reference specific elements within a list.

Data Type of Multiple Values

So far, each variable can only hold one value at a time - one integer or one float or one string. What if we wanted to hold multiple values? Like a list of prime numbers under 50? Or a list of names of students?

You can do this in python by creating a list! A list is a python datatype that can hold multiple values and has special functions, like a String. Here’s how you create a list:

numbers = [1,2,3,4,5,6]
names = ["Sally","Harry"]

Notice that it’s similar to a variable assignment statement, except the value uses square brackets ([]), and each value is separated by a comma (,).

Note that lists can hold values of different datatypes!

mixed_list = [1,2,"three",4,"5",true,None]

So once we have a list of values, how do we access them again?

Specific Elements in a List

Funnily enough, we do it exactly the same as we access strings! Just like each character in a string, each element in a list has an index and we use that index to access that value.

indexes of a list

Here’s an example:

Notice how when the list is printed, it prints the entire list, including the brackets and quotes (if it’s a string).

List Slicing

Similar to strings, you can also slice lists using the same notation.

An important note - please see that in our last example, printing numbers[4:5] returned a list with the value in the 4th index. This is not the same as printing numbers[4]!

numbers[4:5] returns a list with the value at the 4th index. numbers[4] just returns the value at the 4th index.

We won’t be using list indexing as much in this course, but it was an interesting tidbit to share.

Checks For Understanding



Next Section - Lesson 05-02: Looping over Lists