Lists

A list holds many values in order, inside square brackets:

fruits = ["apple", "banana", "cherry"]

0"apple"-3

1"banana"-2

2"cherry"-1

fruits[0] reads an item (indexes start at 0, like strings)
fruits[1] = "kiwi" replaces an item, because lists are mutable
fruits.append("date") adds to the end
len(fruits) counts items

See it run

fruits = ["fig", "kiwi", "lime"]
fruits.append("plum")
fruits[0] = "pear"
print(fruits[-1], len(fruits))

One list, changed in place. Watch the same box grow and change.

Practice lists

Exercise 1

Start with fruits = ["apple", "banana", "cherry"]. Append "date", then replace "banana" with "blueberry" by index. Print len(fruits).

Exercise 2

Use the playlist in the editor below. The radio host wants to:

append "Outro" to the end
replace the first song with "Sunrise" by index
set first to the first song and last to the last song (use a negative index), after the changes
set count to the number of songs

Exercise 3

In the line list in the editor below, the first and last people want to swap places. Swap line[0] and line[-1] using indexes (don't retype the names), then append "Eve", who just arrived. The result should be ["Dee", "Ben", "Cy", "Ana", "Eve"].

The explanation and tasks are public. Running this lesson requires an account with course access.

Practice

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Memory · names → values

Variables appear here as Python creates them.

Output & plots