def find_active_neighbors_for_fixed_links(grid):
"""Find active link neighbors for every fixed link.
Specialized link ID function used to ID the active links that neighbor
fixed links in the vertical and horizontal directions.
If the user wants to assign fixed gradients or values to the fixed
links dynamically, this function identifies the nearest active_link
neighbor.
Each fixed link can either have 0 or 1 active neighbor. This function
finds if and where that active neighbor is and stores those IDs in
an array.
Parameters
----------
grid : RasterModelGrid
A landlab grid.
Returns
-------
ndarray of int, shape `(*, )`
Flat array of links.
Examples
--------
>>> from landlab.grid.structured_quad.links import neighbors_at_link
>>> from landlab import NodeStatus, RasterModelGrid
>>> from landlab.components.overland_flow.generate_overland_flow_deAlmeida import find_active_neighbors_for_fixed_links
>>> grid = RasterModelGrid((4, 5))
>>> grid.status_at_node[:5] = NodeStatus.FIXED_GRADIENT
>>> grid.status_at_node[::5] = NodeStatus.FIXED_GRADIENT
>>> grid.status_at_node # doctest: +NORMALIZE_WHITESPACE
array([2, 2, 2, 2, 2,
2, 0, 0, 0, 1,
2, 0, 0, 0, 1,
2, 1, 1, 1, 1], dtype=uint8)
>>> grid.fixed_links
array([ 5, 6, 7, 9, 18])
>>> grid.active_links
array([10, 11, 12, 14, 15, 16, 19, 20, 21, 23, 24, 25])
>>> find_active_neighbors_for_fixed_links(grid)
array([14, 15, 16, 10, 19])
>>> rmg = RasterModelGrid((4, 7))
>>> rmg.at_node['topographic__elevation'] = rmg.zeros(at='node')
>>> rmg.at_link['topographic__slope'] = rmg.zeros(at='link')
>>> rmg.status_at_node[rmg.perimeter_nodes] = rmg.BC_NODE_IS_FIXED_GRADIENT
>>> find_active_neighbors_for_fixed_links(rmg)
array([20, 21, 22, 23, 24, 14, 17, 27, 30, 20, 21, 22, 23, 24])
"""
neighbors = links.neighbors_at_link(grid.shape, grid.fixed_links).flat
return neighbors[np.in1d(neighbors, grid.active_links)]
def find_active_neighbors_for_fixed_links(grid):
"""Find active link neighbors for every fixed link.
Specialized link ID function used to ID the active links that neighbor
fixed links in the vertical and horizontal directions.
If the user wants to assign fixed gradients or values to the fixed
links dynamically, this function identifies the nearest active_link
neighbor.
Each fixed link can either have 0 or 1 active neighbor. This function
finds if and where that active neighbor is and stores those IDs in
an array.
Parameters
----------
grid : RasterModelGrid
A landlab grid.
Returns
-------
ndarray of int, shape `(*, )`
Flat array of links.
Examples
--------
>>> from landlab.grid.structured_quad.links import neighbors_at_link
>>> from landlab import RasterModelGrid
>>> from landlab.components.overland_flow.generate_overland_flow_deAlmeida import find_active_neighbors_for_fixed_links
>>> from landlab import RasterModelGrid, FIXED_GRADIENT_BOUNDARY
>>> grid = RasterModelGrid((4, 5))
>>> grid.status_at_node[:5] = FIXED_GRADIENT_BOUNDARY
>>> grid.status_at_node[::5] = FIXED_GRADIENT_BOUNDARY
>>> grid.status_at_node # doctest: +NORMALIZE_WHITESPACE
array([2, 2, 2, 2, 2,
2, 0, 0, 0, 1,
2, 0, 0, 0, 1,
2, 1, 1, 1, 1], dtype=uint8)
>>> grid.fixed_links
array([ 5, 6, 7, 9, 18])
>>> grid.active_links
array([10, 11, 12, 14, 15, 16, 19, 20, 21, 23, 24, 25])
>>> find_active_neighbors_for_fixed_links(grid)
array([14, 15, 16, 10, 19])
>>> rmg = RasterModelGrid((4, 7))
>>> rmg.at_node['topographic__elevation'] = rmg.zeros(at='node')
>>> rmg.at_link['topographic__slope'] = rmg.zeros(at='link')
>>> rmg.set_fixed_link_boundaries_at_grid_edges(True, True, True, True)
>>> find_active_neighbors_for_fixed_links(rmg)
array([20, 21, 22, 23, 24, 14, 17, 27, 30, 20, 21, 22, 23, 24])
"""
neighbors = links.neighbors_at_link(grid.shape, grid.fixed_links).flat
return neighbors[np.in1d(neighbors, grid.active_links)]