Step by Step solution about How to resolve the algorithm Ranking methods step by step in the Python programming language

Explanation of the Python Code:

This Python code defines five ranking functions (mc_rank, sc_rank, d_rank, o_rank, and f_rank) and demonstrates their usage for ranking a list of scores.

1. Ranking Functions:

The code defines five ranking functions:

• mc_rank: Modified competition ranking.
• sc_rank: Standard competition ranking.
• d_rank: Dense ranking.
• o_rank: Ordinal ranking.
• f_rank: Fractional ranking.

These functions take an iterable (such as a list) of tuples as input, where each tuple represents a score and a name. They yield tuples containing a rank (position) and the corresponding score and name.

Implementation of Ranking Functions:

• mc_rank:

  • Keeps track of the last result and a FIFO (first-in, first-out) queue.
  • If the current score matches the last result, it's added to the queue.
  • If the current score is different, it iterates over the queue, yielding the rank and the queued scores.
  • Updates the last result and the queue.

• sc_rank:

  • Keeps track of the last result and the last rank.
  • If the current score matches the last result, it yields the last rank and the score.
  • Otherwise, it yields the current rank and updates the last result and last rank.

• d_rank:

  • Keeps track of the last result and the last rank (starting as start-1).
  • If the current score matches the last result, it yields the last rank and the score.
  • Otherwise, it updates the last result and last rank, then yields the current rank and the score.

• o_rank:

  • Simply enumerates the iterable, starting from start.

• f_rank:

  • Keeps track of the last result and a FIFO queue.
  • If the current score doesn't match the last result, it calculates the mean rank of the previous group of scores with the same result.
  • Updates the last result and adds the current score to the queue.

Usage of Ranking Functions:

The code includes a list of scores, each represented as a tuple of the score and the score owner's name. It then demonstrates the usage of the ranking functions by iterating over the scores and printing the rank and the corresponding score and name for each function.

Output:

The code outputs the ranked scores using the five different ranking methods. This shows how each ranking method assigns different rankings to the scores based on their scoring criteria and the rules defined in each ranking function.

def mc_rank(iterable, start=1):
    """Modified competition ranking"""
    lastresult, fifo = None, []
    for n, item in enumerate(iterable, start-1):
        if item[0] == lastresult:
            fifo += [item]
        else:
            while fifo:
                yield n, fifo.pop(0)
            lastresult, fifo = item[0], fifo + [item]
    while fifo:
        yield n+1, fifo.pop(0)


def sc_rank(iterable, start=1):
    """Standard competition ranking"""
    lastresult, lastrank = None, None
    for n, item in enumerate(iterable, start):
        if item[0] == lastresult:
            yield lastrank, item
        else:
            yield n, item
            lastresult, lastrank = item[0], n


def d_rank(iterable, start=1):
    """Dense ranking"""
    lastresult, lastrank = None, start - 1,
    for item in iterable:
        if item[0] == lastresult:
            yield lastrank, item
        else:
            lastresult, lastrank = item[0], lastrank + 1
            yield lastrank, item


def o_rank(iterable, start=1):
    """Ordinal  ranking"""
    yield from enumerate(iterable, start)


def f_rank(iterable, start=1):
    """Fractional ranking"""
    last, fifo = None, []
    for n, item in enumerate(iterable, start):
        if item[0] != last:
            if fifo:
                mean = sum(f[0] for f in fifo) / len(fifo)
                while fifo:
                    yield mean, fifo.pop(0)[1]
        last = item[0]
        fifo.append((n, item))
    if fifo:
        mean = sum(f[0] for f in fifo) / len(fifo)
        while fifo:
            yield mean, fifo.pop(0)[1]


if __name__ == '__main__':
    scores = [(44, 'Solomon'),
              (42, 'Jason'),
              (42, 'Errol'),
              (41, 'Garry'),
              (41, 'Bernard'),
              (41, 'Barry'),
              (39, 'Stephen')]

    print('\nScores to be ranked (best first):')
    for s in scores:
        print('        %2i %s' % (s ))
    for ranker in [sc_rank, mc_rank, d_rank, o_rank, f_rank]:
        print('\n%s:' % ranker.__doc__)
        for rank, score in ranker(scores):
            print('  %3g, %r' % (rank, score))