元组中元素的比较

Question

So I have got a

list = [(0, [2, 0, 4], 1), (3, [2, 0, 4], 2), (1, [3, 0, 4], 2), (2, [3, 0, 4], 2)] 

Its elements are tuples that include:

1. An ID as its first element
2. A list within that always includes three random integers
3. A time

Assume that this list will not be empty. I am struggling to write code that compares each individual component of the tuple elements and appending to a new list depending on a set of criteria.

First criteria is the lists in the middle of each tuple element. I want to compare each tuple whose middle lists are the same, so in my list above comparing list[0] to list[1] and list[2] to list[3]. If there is a tuple with no duplicate list in the middle as any other tuples then append that tuple to a new empty list.

Then for the elements with the matching lists within the tuples I want to compare the time values of those tuples, if it is the lowest time value for the tuples with the matching middle lists then that tuple will be appended to the new empty list. However, if this value is the same for the tuples with the matching middle lists I then want to compare their IDs and pick the lowest ID value.

For the example list above the desired output would be [(0, [2, 0, 4], 1), (1, [3, 0, 4], 2)] because for the tuples with the matching list [2, 0, 4] the lowest value for time was 1 while for the tuples with matching list [3, 0, 4] and a matching value for time the lowest ID value was 1.

If there is anything needed to be clarified I will try my best to answer.

Answer 1

First, map the list according to the numbers in the middle, then take items from the mapping and append items according to your criteria:

from collections import defaultdict
input_ = [(0, [2, 0, 4], 1), (3, [2, 0, 4], 2), (1, [3, 0, 4], 2), (2, [3, 0, 4], 2)] 

mapping = defaultdict(list)

for item in input_:
    mapping[tuple(item[1])].append(item)

output = []

for value in mapping.values():
    if len(value) == 1:
        output.append(value[0])
        continue
    output.append(min(value, key=lambda x: (x[2], x[0])))

print(output)

Output:

[(0, [2, 0, 4], 1), (1, [3, 0, 4], 2)]