Lesson 05-01: Python Lists¶
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.
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.