import heapq


def nlargest_indices(n, iterable):
    """Given an iterable, computes the indices of the n largest items.

    Parameters
    ----------
    n : int
        How many indices to retrieve.
    iterable : iterable
        The iterable from which to compute the n largest indices.

    Returns
    -------
    largest : list of int
        The n largest indices where largest[i] is the index of the i-th largest index.

    """
    nlargest = heapq.nlargest(n, enumerate(iterable),
                              key=lambda x: x[1])
    return [i[0] for i in nlargest]