Sorting tuples in python and keeping the relative order

Input = [("M", 19), ("H", 19), ("A", 25)]

Output =[("A", 25), ("M" ,19), ("H", 19)]

It should sort alphabetically but when the second value is equal then it should remain in place without changing their respective places. Here M and H both have value as 19 so it is already sorted.

You could group the items by the second value of each tuple using itertools.groupby, sort groupings by the first item in each group, then flatten the result with itertools.chain.from_iterable:

from operator import itemgetter
from itertools import groupby, chain

def relative_sort(Input):
    return list(
        chain.from_iterable(
            sorted(
                (
                    tuple(g)
                    for _, g in groupby(
                        sorted(Input, key=itemgetter(1)), key=itemgetter(1)
                    )
                ),
                key=itemgetter(0),
            )
        )
    )

Output:

>>> relative_sort([("M", 19), ("H", 19), ("A", 25)])
[('A', 25), ('M', 19), ('H', 19)]
>>> relative_sort([("B", 19), ("B", 25), ("M", 19), ("H", 19), ("A", 25)])
[('B', 19), ('M', 19), ('H', 19), ('B', 25), ('A', 25)]
>>> relative_sort([("A", 19), ("B", 25), ("M", 19), ("J", 30), ("H", 19)])
[('A', 19), ('M', 19), ('H', 19), ('B', 25), ('J', 30)]