Python Triangulation.set_mask方法代码示例

# 需要导入模块: from matplotlib.tri.triangulation import Triangulation [as 别名]
# 或者: from matplotlib.tri.triangulation.Triangulation import set_mask [as 别名]

#.........这里部分代码省略.........
        # hint: each apex is shared by 2 masked_triangles except the borders.
        borders = np.sum(neighbors == -1)
        added_pts = (3*ntri + borders) / 2
        refi_npts = npts + added_pts
        refi_x = np.zeros(refi_npts)
        refi_y = np.zeros(refi_npts)

        # First part of refi_x, refi_y is just the initial points
        refi_x[:npts] = x
        refi_y[:npts] = y

        # Second part contains the edge midside nodes.
        # Each edge belongs to 1 triangle (if border edge) or is shared by 2
        # masked_triangles (interior edge).
        # We first build 2 * ntri arrays of edge starting nodes (edge_elems,
        # edge_apexes) ; we then extract only the masters to avoid overlaps.
        # The so-called 'master' is the triangle with biggest index
        # The 'slave' is the triangle with lower index
        # (can be -1 if border edge)
        # For slave and master we will identify the apex pointing to the edge
        # start
        edge_elems = np.ravel(np.vstack([np.arange(ntri, dtype=np.int32),
                                         np.arange(ntri, dtype=np.int32),
                                         np.arange(ntri, dtype=np.int32)]))
        edge_apexes = np.ravel(np.vstack([np.zeros(ntri, dtype=np.int32),
                                          np.ones(ntri, dtype=np.int32),
                                          np.ones(ntri, dtype=np.int32)*2]))
        edge_neighbors = neighbors[edge_elems, edge_apexes]
        mask_masters = (edge_elems > edge_neighbors)

        # Identifying the "masters" and adding to refi_x, refi_y vec
        masters = edge_elems[mask_masters]
        apex_masters = edge_apexes[mask_masters]
        x_add = (x[triangles[masters, apex_masters]] +
                 x[triangles[masters, (apex_masters+1) % 3]]) * 0.5
        y_add = (y[triangles[masters, apex_masters]] +
                 y[triangles[masters, (apex_masters+1) % 3]]) * 0.5
        refi_x[npts:] = x_add
        refi_y[npts:] = y_add

        # Building the new masked_triangles ; each old masked_triangles hosts
        # 4 new masked_triangles
        # there are 6 pts to identify per 'old' triangle, 3 new_pt_corner and
        # 3 new_pt_midside
        new_pt_corner = triangles

        # What is the index in refi_x, refi_y of point at middle of apex iapex
        #  of elem ielem ?
        # If ielem is the apex master: simple count, given the way refi_x was
        #  built.
        # If ielem is the apex slave: yet we do not know ; but we will soon
        # using the neighbors table.
        new_pt_midside = np.empty([ntri, 3], dtype=np.int32)
        cum_sum = npts
        for imid in range(3):
            mask_st_loc = (imid == apex_masters)
            n_masters_loc = np.sum(mask_st_loc)
            elem_masters_loc = masters[mask_st_loc]
            new_pt_midside[:, imid][elem_masters_loc] = np.arange(
                n_masters_loc, dtype=np.int32) + cum_sum
            cum_sum += n_masters_loc

        # Now dealing with slave elems.
        # for each slave element we identify the master and then the inode
        # onces slave_masters is indentified, slave_masters_apex is such that:
        # neighbors[slaves_masters, slave_masters_apex] == slaves
        mask_slaves = np.logical_not(mask_masters)
        slaves = edge_elems[mask_slaves]
        slaves_masters = edge_neighbors[mask_slaves]
        diff_table = np.abs(neighbors[slaves_masters, :] -
                            np.outer(slaves, np.ones(3, dtype=np.int32)))
        slave_masters_apex = np.argmin(diff_table, axis=1)
        slaves_apex = edge_apexes[mask_slaves]
        new_pt_midside[slaves, slaves_apex] = new_pt_midside[
            slaves_masters, slave_masters_apex]

        # Builds the 4 child masked_triangles
        child_triangles = np.empty([ntri*4, 3], dtype=np.int32)
        child_triangles[0::4, :] = np.vstack([
            new_pt_corner[:, 0], new_pt_midside[:, 0],
            new_pt_midside[:, 2]]).T
        child_triangles[1::4, :] = np.vstack([
            new_pt_corner[:, 1], new_pt_midside[:, 1],
            new_pt_midside[:, 0]]).T
        child_triangles[2::4, :] = np.vstack([
            new_pt_corner[:, 2], new_pt_midside[:, 2],
            new_pt_midside[:, 1]]).T
        child_triangles[3::4, :] = np.vstack([
            new_pt_midside[:, 0], new_pt_midside[:, 1],
            new_pt_midside[:, 2]]).T
        child_triangulation = Triangulation(refi_x, refi_y, child_triangles)

        # Builds the child mask
        if triangulation.mask is not None:
            child_triangulation.set_mask(np.repeat(triangulation.mask, 4))

        if ancestors is None:
            return child_triangulation
        else:
            return child_triangulation, np.repeat(ancestors, 4)