functions.py 文件源码

def gacPathCondEntropy(IminuszW, cluster_i, cluster_j):
    # Compute conditional complexity from the subpart of the weighted adjacency matrix
    # Inputs:
    #   - IminuszW: the matrix (I - z*P)
    #   - cluster_i: index vector of cluster i
    #   - cluster_j: index vector of cluster j
    # Output:
    #   - L_ij - the sum of conditional complexities of cluster i and j after merging.
    # by Wei Zhang (wzhang009 at gmail.com), June, 8, 2011

    num_i = np.size(cluster_i)
    num_j = np.size(cluster_j)

    # detecting cross elements (this check costs much and is unnecessary)

    ijGroupIndex = np.append(cluster_i, cluster_j)

    y_ij = np.zeros((num_i + num_j, 2))  # [y_i, y_j]
    y_ij[:num_i, 0] = 1
    y_ij[num_i:, 1] = 1
    idx = np.ix_(ijGroupIndex, ijGroupIndex)
    L_ij = scipy.linalg.inv(IminuszW[idx]).dot(y_ij)
    L_ij = sum(L_ij[:num_i, 0]) / (num_i * num_i) + sum(L_ij[num_i:, 1]) / (num_j * num_j)

    return L_ij