A good way to visualize a 2d array is as a list of lists. Something like this:
lst=[[1,2,3],[4,5,6],[7,8,9]]
here the outer list lst
has three things in it. each of those things is another list:
The first one is: [1,2,3]
, the second one is: [4,5,6]
and the third one is: [7,8,9]
. You can access these lists the same way you would access another other element of a list, like this:
print (lst[0])
#output: [1, 2, 3]
print (lst[1])
#output: [4, 5, 6]
print (lst[2])
#output: [7, 8, 9]
You can then access the different elements in each of those lists the same way:
print (lst[0][0])
#output: 1
print (lst[0][1])
#output: 2
Here the first number inside the []
brackets means get the list in that position. In the above example we used the number 0
to mean get the list in the 0th position which is [1,2,3]
. The second set of []
brackets means get the item in that position from the inner list. In this case we used both 0
and 1
the 0th position in the list we got is the number 1
and in the 1st position it is 2
You can also set values inside these lists the same way:
lst[0]=[10,11,12]
Now the list is [[10,11,12],[4,5,6],[7,8,9]]
. In this example we changed the whole first list to be a completely new list.
lst[1][2]=15
Now the list is [[10,11,12],[4,5,15],[7,8,9]]
. In this example we changed a single element inside of one of the inner lists. First we went into the list at position 1 and changed the element within it at position 2, which was 6 now it's 15.