Need max values in list of tuples, based on position

[Thomas Passin]

On 11/11/2022 2:22 AM, DFS wrote:
> 
> [(0,11), (1,1),  (2,1),
>   (0,1) , (1,41), (2,2),
>   (0,9) , (1,3),  (2,12)]
> 
> The set of values in elements[0] is {0,1,2}
> 
> I want the set of max values in elements[1]: {11,41,12}

This request is ambiguous.  Do you want to get the maximum value for 
each row, and present it in the order of those rows?  Your data list 
does not distinguish the rows from the tuples, so that information must 
come from somewhere else.  Could it sometimes be different from 3?  How 
are we supposed to know?

Also, as has already been noted in this thread, the result cannot 
literally be a set because sets are not ordered but you insisted that 
the order is important.

This code  allows for different length of rows, and tries to be as clear 
as possible:

data = [(0,11), (1,1),  (2,1),
  (0,1), (1,41), (2,2),
  (0,9), (1,3),  (2,12)]

span = 3  # Change for other row lengths

d1 = [y for x, y in data]  # pick out the 2nd member of each tuple
# d1: [11, 1, 1, 1, 41, 2, 9, 3, 12]

groups = []
for i in range(0, len(d1), span):
     group = []
     for s in range(span):
         group.append(d1[i + s])
     groups.append(group)
# groups: [[11, 1, 1], [1, 41, 2], [9, 3, 12]]

maxes = [max(t) for t in groups]
# maxes: [11, 41, 12]

This could be condensed, but I recommend keeping it as clear as 
possible.  Tricky, condensed code becomes harder to understand as time 
goes by.