the key param of sorted function, can we control what it does if 2 elements have same value used to sort the iterable?

Question

Like if the iterable is a list of tuples:
L = [(0, 2), (1, 3), (1, 2), (-1, 2)]

And when we do

print(sorted(L, key = lambda t: t[1]))

it sorts the tuple whose 2nd element is same based on their index in the original list. What if I want to sort the elements whose 2nd value (in this case) is same based on their 1st value?

Like (0, 2) and (1, 2) and (-1, 2) should be sorted as (-1, 2), (0, 2), (1, 2)

Answer 1

In the key lambda, you can use any function or expression to determine the ordering of elements. Sorting by multiple keys is possible if you define a tuple in the lambda like this:

print(sorted(L, key = lambda t: (t[1], t[0])))

In this case the second key is the first element of the original tuples.