How do I get the first max distinct element in a list?

user_6439608 0
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    populations = [[0 1]
                   [1 1]
                   [0 1]
                   [0 1]]

score = [0, 6, 4, 4] best_score = max(score)

What I want to do is to get chromosome_best by first, matching best_score with score and get the index that match in score, then using this index, get its corresponding value in populations

My code so far looks like this:

chromosome_best = numpy.array([d for a, d in zip(score, populations) if a == best_score])

But how could I change it such that when score has non-unique values, example: score = [6, 6, 0, 4] best_score = 6

The chromosome_best that would be read is the first match between score and best_score?

python
3 Answers

Something like populations[score.index(best_score)] should do the trick. list.index returns the first index where the list matches the element you provide, therefore it will always match with the first occurrence, no matter how many there are

user_102935480

The following code snippets should give the first match.

next(d for a, d in zip(score, populations) if a == best_score)
user_73588870

You can use max with a key function:

chromosome_best, best_score = max(zip(populations, score), key=lambda tup: tup[1])

So we zip them together and max determines the maximum of tuples zip gives by looking at their element at 1st index i.e. the score. We unpack the result to get best chromosome (and also best score). max gives the first maximum value encountered among all, so we get the desired result.

This solution traverses the lists only once.

user_93321870
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