Collaction starand rank (1224)

index.php

<?php

use Illuminate\Support\Collection;

require __dir__ . '/vendor/autoload.php';

Collection::macro('pipe', function ($callback) {
    return $callback($this);
});

$scores = [
    ['score' => 76, 'team' => 'A'],
    ['score' => 62, 'team' => 'B'],
    ['score' => 82, 'team' => 'C'],
    ['score' => 86, 'team' => 'D'],
    ['score' => 91, 'team' => 'E'],
    ['score' => 67, 'team' => 'F'],
    ['score' => 67, 'team' => 'G'],
    ['score' => 82, 'team' => 'H'],
];

function rank_scores ($scores) {
    return collect($scores)
        ->pipe(function ($scores) {
            return assign_initial_rankings($scores);
        })
        ->pipe(function ($rankedScores) {
            return adjust_rankings_for_ties($rankedScores);
        });
}

function assign_initial_rankings($scores) {
    return $scores->sortByDesc('score')
        ->zip(range(1, $scores->count()))
        ->map(function ($scoreAndRank) {
            list($score, $rank) = $scoreAndRank;
            return array_merge($score, [
                'rank' => $rank
            ]);
        });
}

function adjust_rankings_for_ties($scores) {
    return $scores->groupBy('score')
        ->map(function ($tiedScores) {
            return apply_min_rank($tiedScores);
        })
        ->collapse()
        ->sortBy('rank');
}

function apply_min_rank($tiedScores) {
    $lowestRank = $tiedScores->pluck('rank')->min();

    return $tiedScores->map(function ($rankedScore) use ($lowestRank) {
        return array_merge($rankedScore, [
            'rank' => $lowestRank
        ]);
    });
}