Two-dimensional lists (arrays) - Learn Python 3 - Snakify

# Lesson 9. Two-dimensional lists (arrays)

### 1/21. Nested lists: processing and printing

In real-world tasks you often have to store rectangular data table. [say more on this!] Such tables are called matrices or two-dimensional arrays. In Python any table can be represented as a list of lists (a list, where each element is in turn a list). For example, here's the program that creates a numerical table with two rows and three columns, and then makes some manipulations with it:

The first element of a here — a[0] — is a list of numbers [1, 2, 3]. The first element of this new list is a[0][0] == 1; moreover, a[0][1] == 2, a[0][2] == 3, a[1][0] == 4, a[1][1] == 5, a[1][2] == 6.

#### Instructions

Click "Run" to see what happens in output!

Let's move on!
a = [[1, 2, 3], [4, 5, 6]]
print(a[0])
print(a[1])
b = a[0]
print(b)
print(a[0][2])
a[0][1] = 7
print(a)
print(b)
b[2] = 9
print(a[0])
print(b)