source_space.py 文件源码

def _do_src_distances(con, vertno, run_inds, limit):
    """Helper to compute source space distances in chunks"""
    if limit < np.inf:
        func = partial(sparse.csgraph.dijkstra, limit=limit)
    else:
        func = sparse.csgraph.dijkstra
    chunk_size = 20  # save memory by chunking (only a little slower)
    lims = np.r_[np.arange(0, len(run_inds), chunk_size), len(run_inds)]
    n_chunks = len(lims) - 1
    # eventually we want this in float32, so save memory by only storing 32-bit
    d = np.empty((len(run_inds), len(vertno)), np.float32)
    min_dist = np.empty((n_chunks, con.shape[0]))
    min_idx = np.empty((n_chunks, con.shape[0]), np.int32)
    range_idx = np.arange(con.shape[0])
    for li, (l1, l2) in enumerate(zip(lims[:-1], lims[1:])):
        idx = vertno[run_inds[l1:l2]]
        out = func(con, indices=idx)
        midx = np.argmin(out, axis=0)
        min_idx[li] = idx[midx]
        min_dist[li] = out[midx, range_idx]
        d[l1:l2] = out[:, vertno]
    midx = np.argmin(min_dist, axis=0)
    min_dist = min_dist[midx, range_idx]
    min_idx = min_idx[midx, range_idx]
    d[d == np.inf] = 0  # scipy will give us np.inf for uncalc. distances
    return d, min_idx, min_dist