CODE EXAMPLE FOR PYTHON

sort tuple by first element python

a = [(5,8), (3,4), (9,7)]

#sort by first element in tuple
result = sorted(a, key=lambda tup: tup[0])

#OR to do inplace sort:

a.sorted(key = lambda tup: tup[0])

# output
[(3, 4), (5, 8), (9, 7)]