Nested Lists

In this chapter you learn:

area	topic
⚙	define a list inside a list
⚙	index a nested list
🔀	loop over a nested list
🔀	create a nested list with a nested loop

Data frequently occurs in the form of tables. To process tables in Python, we can put lists in other lists. These are called nested lists:

table = [
  ["Emma", 20799],
  ["Olivia", 19674],
  ["Sophia", 18490],
  ["Isabella", 16950],
  ["Ava", 15586],
  ["Mia", 13442],
  ["Emily", 12562],
]

Generally, for nested lists, the same rules apply as for single lists. E.g. for the third row:

print(table[2])

To access a single element, you need two pairs of square brackets. E.g. for the second column of the third row:

print(table[2][1])

In this chapter we will create and process nested lists.

Exercise 1

Write all rows of the above table to the screen with a for loop.

Complete the code:

for ... in table:
    print(...):

Exercise 2

Now modify the loop to output only the names.

Exercise 3

Write each individual cell of the table to the screen with a nested for loop.

Complete the code:

for row in ...:
    ... cell in row:
        print(...)

Exercise 4

Create an empty table of 10 x 10 cells and fill them with numbers from 1 to 100.

Sort the lines and indent the code properly:

for x in range(10):
for y in range(10):
number = 1
number += 1
print(table)
row = []
row.append(number)
table.append(row)
table = []