Coding notes

Length check

len(itemoflength)

Range

Uses () not [], normal brackets are for functions like range and square brackets are for indexing

First argument is inclusive. Second argument is not. E.g. for i in range(0,7) will stop and not run if i is 7.

A third argument is the steps. This means you don’t have to increment i yourself. You can choose the direction and amount you want to increment, e.g. 3 or -1.

If you dont include a step, i will still increment by 1 always.

While loops don’t use in range

For loops automatically increment i because the range function has a step parameter even if you don’t sub it in.

No in range means you have to set i as 0 and increment it yourself

Select section of an array

arr[:3]

arr[2:]

First parameter inclusive, second is not

Making an empty 2D array

arr = [[0]*cols]*rows

where cols and rows are integers

Insertion sort

Cannot move all items along and then insert. Must shuffle it down one by one