Returns a pandas DataFrame with the various per-LF statistics.

    Args:
        L: an n x m scipy.sparse matrix where L_{i,j} is the label given by the
            jth LF to the ith candidate
        Y: an [n] or [n, 1] np.ndarray of gold labels.
            If provided, the empirical accuracy for each LF will be calculated

def lf_summary(L, Y=None, lf_names=None, est_accs=None):
    """Returns a pandas DataFrame with the various per-LF statistics.

    Args:
        L: an n x m scipy.sparse matrix where L_{i,j} is the label given by the
            jth LF to the ith candidate
        Y: an [n] or [n, 1] np.ndarray of gold labels.
            If provided, the empirical accuracy for each LF will be calculated
    """
    n, m = L.shape
    if lf_names is not None:
        col_names = ["j"]
        d = {"j": list(range(m))}
    else:
        lf_names = list(range(m))
        col_names = []
        d = {}

    # Default LF stats
    col_names.extend(["Polarity", "Coverage", "Overlaps", "Conflicts"])
    d["Polarity"] = Series(data=lf_polarities(L), index=lf_names)
    d["Coverage"] = Series(data=lf_coverages(L), index=lf_names)
    d["Overlaps"] = Series(data=lf_overlaps(L), index=lf_names)
    d["Conflicts"] = Series(data=lf_conflicts(L), index=lf_names)

    if Y is not None:
        col_names.extend(["Correct", "Incorrect", "Emp. Acc."])
        confusions = [
            confusion_matrix(Y, L[:, i], pretty_print=False) for i in range(m)
        ]
        corrects = [np.diagonal(conf).sum() for conf in confusions]
        incorrects = [
            conf.sum() - correct for conf, correct in zip(confusions, corrects)
        ]
        accs = lf_empirical_accuracies(L, Y)
        d["Correct"] = Series(data=corrects, index=lf_names)
        d["Incorrect"] = Series(data=incorrects, index=lf_names)
        d["Emp. Acc."] = Series(data=accs, index=lf_names)

    if est_accs is not None:
        col_names.append("Learned Acc.")
        d["Learned Acc."] = Series(est_accs, index=lf_names)

    return DataFrame(data=d, index=lf_names)[col_names]