On Wed, Oct 2, 2013 at 3:34 PM, <subhabangal...@gmail.com> wrote: > Dear Group, > > I am trying to work out a solution to the following problem in Python. > > The Problem: > Suppose I have three lists. > Each list is having 10 elements in ascending order. > I have to construct one list having 10 elements which are of the lowest value > among these 30 elements present in the three given lists. > > The Solution: > > I tried to address the issue in the following ways: > > a) I took three lists, like, > list1=[1,2,3,4,5,6,7,8,9,10] > list2=[0,1,2,3,4,5,6,7,8,9] > list3=[-5,-4,-3,-2,-1,0,1,2,3,4] > > I tried to make sum and convert them as set to drop the repeating elements: > set_sum=set(list1+list2+list3) > set([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, -1, -5, -4, -3, -2]) > > In the next step I tried to convert it back to list as, > list_set=list(set_sum) > gave the value as, > [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, -1, -5, -4, -3, -2] > > Now, I imported heapq as, > import heapq > > and took the result as, > result=heapq.nsmallest(10,list_set) > it gave as, > [-5, -4, -3, -2, -1, 0, 1, 2, 3, 4] > > b) I am thinking to work out another approach. > I am taking the lists again as, > > list1=[1,2,3,4,5,6,7,8,9,10] > list2=[0,1,2,3,4,5,6,7,8,9] > list3=[-5,-4,-3,-2,-1,0,1,2,3,4] > > as they are in ascending order, I am trying to take first four/five elements > of each list,like, > > list1_4=list1[:4] >>>> list2_4=list2[:4] >>>> list3_4=list3[:4] > > Now, I am trying to add them as, > > list11=list1_4+list2_4+list3_4 > > thus, giving us the result > > [1, 2, 3, 4, 0, 1, 2, 3, -5, -4, -3, -2] > > Now, we are trying to sort the list of the set of the sum as, > > sort_sum=sorted(list(set(list11))) > > giving us the required result as, > > [-5, -4, -3, -2, 0, 1, 2, 3, 4] > > If by taking the value of each list portion as 4 gives as less number of > elements in final value, as we are making set to avoid repeating numbers, we > increase element count by one or two and if final result becomes more than 10 > we take first ten. > > Are these approaches fine. Or should we think some other way. > > If any learned member of the group can kindly let me know how to solve I > would be helpful enough. > > Thanking in Advance, > Subhabrata. > > > -- > https://mail.python.org/mailman/listinfo/python-list
[Disclaimer: Beginner myself] The heapq module has merge Since the lists are already sorted what's wrong with just this? list(merge(list1, list2, list3))[:10] -- - Ravi -- https://mail.python.org/mailman/listinfo/python-list
