Lists

Question

What is the purpose of having two brackets around a list? For example
List = [[a, b, c]]

Answer 1

Let me give you some examples.

lst = [1, 2, 3]
list = [[1, 2, 3]]

lst has three elements, but list has 1.

lst.append(list[0])
now,
lst = [1, 2, 3, [1,2,3]]

so, it has 4 elements now.
Hope it helped

Answer 2

Your example is a list within a list = a nested list: The inner list contains a, b, c while the outer list contains the inner list.

[[a, b], c]
In thos example, the outer list contains a list (containing a and b) and c

Answer 3

points=[[3,7],[2,3],[4,8]]
could be a list of points with x and y coordinates.

Answer 4

wow. this community is awesome. thanks everyone.