How do index's increase in python 2D lists?-CodePudding

new to python - re the below code.

I'm confused as to why the index for 7 is [2][2]. I expected it to be [4][0], given that up until this point I had learned that indexes increased by going [0][0], [0][1], [1][0], etc. Any help appreciated - ty.

#Checkpoint 1
incoming_class = [["Kenny", "American", 9], ["Tanya", "Russian", 9], ["Madison", "Indian", 7]]

print(incoming_class)

#Checkpoint 2
incoming_class[2][2] = 8

print(incoming_class)

CodePudding user response：

Think of it this way:

#                     0          1        2
incoming_class = [["Kenny",   "American", 9],  # 0
                  ["Tanya",   "Russian",  9],  # 1
                  ["Madison", "Indian",   7]]  # 2

When we say incoming_class[2][2], we mean to take

row #2, i.e. the element with index 2 from incoming_class (["Madison", "Indian", 7])
- incoming_class[2] == ["Madison", "Indian", 7]
colmn #2, i.e. the element with index 2 from what we just found (7).
- incoming_class[2][2] == 7

CodePudding user response：

As explained in the comment by @cory-kramer you have a list of lists.

Every element of the list is indexed by the first number so [0][x], [1][x], and so on. Because it's a list of lists, every element of the list is actually another list, and it has a number of elements itself indexed by another index so, for the first list you have [0][0], [0][1] and so on.

In your case the element 7 is [2][2]

I suggest checking how lists work in Python here