How to sort a a Python List on two fields

I have used the following code to merge 2 list items. For example, list 'c' is a creation of list variables 'a' and 'b'

a=[['2022', 4], ['2023', 5]]
b=["Random1","Random2"]
c=list(zip(a,b))

'c' therefore looks like this

Out[]: [(['2022', 4], 'Random1'), (['2023', 5], 'Random2')]

i tried to sort 'c' on the 2nd and 3rd column i.e.

c_sorted=c.sort(key=lambda i:(i[1],i[2]))

however i get the error
IndexError: tuple index out of range

Any help would be greatly appreciated! thanks!

You're not exactly getting 3 equal columns after the merge, but rather a tuple of a list and a plain value as you posted:

Out[]: [(['2022', 4], 'Random1'), (['2023', 5], 'Random2')]

You want to properly index on the columns and it should work:

>>> sorted(c, key=lambda i:(i[0][1], i[1]))
[(['2022', 4], 'Random1'), (['2023', 5], 'Random2')]

You might be tempted to attempt something like

key = lambda ((year, number), random_string): (number, random_string) 

but this was actually removed in PEP 3113

Alternatively you could truly merge the lists to the result you wanted with this list comprehension instead of the plain list call:

>>> [x + [y] for x, y in zip(a, b)]
[['2022', 4, 'Random1'], ['2023', 5, 'Random2']]

Now your initial code should work fine.

"IndexError: tuple index out of range," occurs because the elements in your list c are tuples, and you are trying to access the second and third indices of each tuple. However, the tuples in c have only two elements: the first element from a and the corresponding element from b.
corrected answer can be:

a = [['2022', 4], ['2023', 5]]
b = ["Random1", "Random2"]
c = list(zip(a, b))

c_sorted = sorted(c, key=lambda i: (i[0][1], i[1]))
print(c_sorted)

i0 accesses the second element (1) of the sublist (i[0]) from a. This is the value you want to use for the initial sorting. i1 accesses the corresponding element from b. This is the value you want to use as the secondary sorting criterion.