lis = [['2016-10-01,83928373'],['2016-10-01,83928373'],['2016-10-02,93928373'],['2016-10-01,234242'],['2016-10-02,90384102']]

dict_day = {}

list_a = []

list_b = []

for tmp in lis:

tmp = tmp[0]

list_a = tmp.split(',')

a = list_a[0]

b = list_a[1]

list_b.append(a)

dict_day.setdefault(a,[]).append(b)

list_max = []

dict_max = {}

for i in list_b:

list_r = [int(t) for t in dict_day[i]]

list_r.sort(reverse=True)

a = list_r[0]

dict_max[i] = a

list_max.append(a)

for key in dict_day:

sorted_x = sorted(dict_max.iteritems(), key=lambda dict_max : dict_max[1], reverse=True)

list_sort = list(sorted_x)

list_1 = [list(i) for i in sorted_x]

print list_1

for i in list_1:

list_2 = [str(t) for t in i]

print list_2[0]+","+list_2[1]

print ','.join(list(sorted_x[0]))

list_max.sort(reverse=True)