如何在Python中对具有相同名称的元组的值求和

 

mylist=[(3, 'a'), (7, 'b'), (4, 'a'), (5, 'c'), (2, 'a'), (1, 'b')]

  import itertools
[(sum(i[0] for i in group), key) for key, group in itertools.groupby(sorted(mylist, key = lambda i: i[1]), lambda i: i[1])]

[(9, 'a'), (8, 'b'), (5, 'c')]