landlab.grid.unstructured.links

class LinkGrid

Bases: object

Create a grid of links that enter and leave nodes. __init__((node0, node1), number_of_nodes=None)

Parameters:

• node0 (sequence of array-like) – Node ID at link start and end.

• node1 (sequence of array-like) – Node ID at link start and end.

• number_of_nodes (int, optional) – Number of nodes in the grid

Returns:

A newly-created grid

Return type:

LinkGrid

Examples

>>> from landlab.grid.unstructured.links import LinkGrid
>>> lgrid = LinkGrid([(0, 1, 0, 2, 0), (2, 3, 1, 3, 3)], 4)
>>> lgrid.number_of_links
5
>>> lgrid.number_of_nodes
4
>>> lgrid.number_of_in_links_at_node(0)
0
>>> lgrid.number_of_out_links_at_node(0)
3
>>> lgrid.out_link_at_node(0)
array([0, 2, 4])
>>> lgrid.nodes_at_link_id(1)
array([1, 3])

>>> lgrid = LinkGrid([(0, 1, 0, 2, 0), (2, 3, 1, 3, 3)], 4, link_ids=range(1, 6))
>>> lgrid.nodes_at_link
array([[0, 2],
       [1, 3],
       [0, 1],
       [2, 3],
       [0, 3]])
>>> lgrid.out_link_at_node(0)
array([1, 3, 5])
>>> lgrid.nodes_at_link_id(1)
array([0, 2])

Create a grid of links that enter and leave nodes. __init__((node0, node1), number_of_nodes=None)

Parameters:

• node0 (sequence of array-like) – Node ID at link start and end.

• node1 (sequence of array-like) – Node ID at link start and end.

• number_of_nodes (int, optional) – Number of nodes in the grid

Returns:

A newly-created grid

Return type:

LinkGrid

Examples

>>> from landlab.grid.unstructured.links import LinkGrid
>>> lgrid = LinkGrid([(0, 1, 0, 2, 0), (2, 3, 1, 3, 3)], 4)
>>> lgrid.number_of_links
5
>>> lgrid.number_of_nodes
4
>>> lgrid.number_of_in_links_at_node(0)
0
>>> lgrid.number_of_out_links_at_node(0)
3
>>> lgrid.out_link_at_node(0)
array([0, 2, 4])
>>> lgrid.nodes_at_link_id(1)
array([1, 3])

>>> lgrid = LinkGrid(
...     [(0, 1, 0, 2, 0), (2, 3, 1, 3, 3)], 4, link_ids=range(1, 6)
... )
>>> lgrid.nodes_at_link
array([[0, 2],
       [1, 3],
       [0, 1],
       [2, 3],
       [0, 3]])
>>> lgrid.out_link_at_node(0)
array([1, 3, 5])
>>> lgrid.nodes_at_link_id(1)
array([0, 2])

__init__(link_ends, number_of_nodes, link_ids=None, node_status=None)

Create a grid of links that enter and leave nodes. __init__((node0, node1), number_of_nodes=None)

Parameters:

• node0 (sequence of array-like) – Node ID at link start and end.

• node1 (sequence of array-like) – Node ID at link start and end.

• number_of_nodes (int, optional) – Number of nodes in the grid

Returns:

A newly-created grid

Return type:

LinkGrid

Examples

>>> from landlab.grid.unstructured.links import LinkGrid
>>> lgrid = LinkGrid([(0, 1, 0, 2, 0), (2, 3, 1, 3, 3)], 4)
>>> lgrid.number_of_links
5
>>> lgrid.number_of_nodes
4
>>> lgrid.number_of_in_links_at_node(0)
0
>>> lgrid.number_of_out_links_at_node(0)
3
>>> lgrid.out_link_at_node(0)
array([0, 2, 4])
>>> lgrid.nodes_at_link_id(1)
array([1, 3])

>>> lgrid = LinkGrid(
...     [(0, 1, 0, 2, 0), (2, 3, 1, 3, 3)], 4, link_ids=range(1, 6)
... )
>>> lgrid.nodes_at_link
array([[0, 2],
       [1, 3],
       [0, 1],
       [2, 3],
       [0, 3]])
>>> lgrid.out_link_at_node(0)
array([1, 3, 5])
>>> lgrid.nodes_at_link_id(1)
array([0, 2])

__new__(**kwargs)

in_link_at_node(node)

Links entering a node.

Parameters:

node (int) – Node ID

Returns:

Links entering the node

Return type:

ndarray

Examples

>>> from landlab.grid.unstructured.links import LinkGrid
>>> lgrid = LinkGrid([(0, 1, 0, 2), (2, 3, 1, 3)], 4)
>>> len(lgrid.in_link_at_node(0)) == 0
True
>>> lgrid.in_link_at_node(3)
array([1, 3])

iter_nodes()

Iterate of the nodes of the grid.

Returns:

Links entering and leaving each node

Return type:

ndarray

Examples

>>> from landlab.grid.unstructured.links import LinkGrid
>>> lgrid = LinkGrid([(0, 1, 0, 2), (2, 3, 1, 3)], 4)
>>> for link in lgrid.iter_nodes():
...     link
...
array([0, 2])
array([2, 1])
array([0, 3])
array([1, 3])

property link_id

property node_at_link_end

property node_at_link_start

property node_status_at_link_end

property node_status_at_link_start

property nodes_at_link

nodes_at_link_id(link_id)

number_of_in_links_at_node(node)

Number of links entering a node.

Parameters:

node (int) – Node ID

Returns:

Number of links entering the node.

Return type:

int

Examples

>>> from landlab.grid.unstructured.links import LinkGrid
>>> lgrid = LinkGrid([(0, 1, 0, 2), (2, 3, 1, 3)], 4)
>>> [lgrid.number_of_in_links_at_node(node) for node in range(4)]
[0, 1, 1, 2]

property number_of_links

Number of links in the grid.

number_of_links_at_node(node)

Number of links entering and leaving a node.

Parameters:

node (int) – Node ID

Returns:

Number of links entering and leaving the node.

Return type:

int

Examples

>>> from landlab.grid.unstructured.links import LinkGrid
>>> lgrid = LinkGrid([(0, 1, 0, 2), (2, 3, 1, 3)], 4)
>>> [lgrid.number_of_links_at_node(node) for node in range(4)]
[2, 2, 2, 2]

property number_of_nodes

Number of nodes in the grid.

number_of_out_links_at_node(node)

Number of links leaving a node.

Parameters:

node (int) – Node ID

Returns:

Number of links leaving the node.

Return type:

int

Examples

>>> from landlab.grid.unstructured.links import LinkGrid
>>> lgrid = LinkGrid([(0, 1, 0, 2), (2, 3, 1, 3)], 4)
>>> [lgrid.number_of_out_links_at_node(node) for node in range(4)]
[2, 1, 1, 0]

out_link_at_node(node)

Links leaving a node.

Parameters:

node (int) – Node ID

Returns:

Links leaving the node

Return type:

ndarray

Examples

>>> from landlab.grid.unstructured.links import LinkGrid
>>> lgrid = LinkGrid([(0, 1, 0, 2), (2, 3, 1, 3)], 4)
>>> lgrid.out_link_at_node(0)
array([0, 2])
>>> len(lgrid.out_link_at_node(3)) == 0
True

find_active_links(node_status, node_at_link_ends)

find_active_links(node_status, (node0, node1)) IDs of active links.

Parameters:

• node_status (ndarray) – Status of nodes.

• node0 (sequence of array-like) – Node ID at link start and end.

• node1 (sequence of array-like) – Node ID at link start and end.

Returns:

Links IDs of active links.

Return type:

ndarray

Examples

>>> from landlab.grid.unstructured.links import find_active_links
>>> links = [(0, 2), (1, 3), (0, 1), (1, 2), (0, 3)]
>>> status = np.array([0, 0, 0, 0])
>>> find_active_links(status, links)
array([0, 1, 2, 3, 4])

in_link_count_per_node(node_at_link_ends, number_of_nodes=0)

in_link_count_per_node((node0, node1), number_of_nodes=0) Number of links entering nodes.

Parameters:

• node0 (sequence of array-like) – Node ID at link start and end.

• node1 (sequence of array-like) – Node ID at link start and end.

• number_of_nodes (int, optional) – Number of nodes in the grid

Returns:

Number of links entering nodes.

Return type:

ndarray

Examples

>>> from landlab.grid.unstructured.links import in_link_count_per_node
>>> link_ends = [(0, 3), (1, 4), (2, 5), (3, 6), (4, 7), (5, 8)]
>>> in_link_count_per_node(zip(*link_ends))
array([0, 0, 0, 1, 1, 1, 1, 1, 1])

in_link_ids_at_node(node_at_link_ends, link_ids=None, number_of_nodes=0)

in_link_ids_at_node((node0, node1), number_of_nodes=0) Links entering nodes.

Parameters:

• node0 (sequence of array-like) – Node ID at link start and end.

• node1 (sequence of array-like) – Node ID at link start and end.

• number_of_nodes (int, optional) – Number of nodes in the grid

Returns:

Tuple of link id array and offset into link id array.

Return type:

tuple

Examples

>>> from landlab.grid.unstructured.links import in_link_ids_at_node
>>> (links, count) = in_link_ids_at_node(([0, 1, 2, 3, 4, 5], [3, 4, 5, 6, 7, 8]))
>>> links
array([0, 1, 2, 3, 4, 5])
>>> count
array([0, 0, 0, 1, 1, 1, 1, 1, 1])

>>> (links, count) = in_link_ids_at_node(
...     ([0, 1, 2, 3, 4, 5], [3, 4, 5, 6, 7, 8]), link_ids=range(1, 7)
... )
>>> links
array([1, 2, 3, 4, 5, 6])
>>> count
array([0, 0, 0, 1, 1, 1, 1, 1, 1])

link_count_per_node(node_at_link_ends, number_of_nodes=None)

link_count_per_node((node0, node1), number_of_nodes=None) Number of links per node.

Parameters:

• node0 (sequence of array-like) – Node ID at link start and end.

• node1 (sequence of array-like) – Node ID at link start and end.

• number_of_nodes (int, optional) – Number of nodes in the grid

Returns:

Number of links per nodes.

Return type:

ndarray

Examples

>>> from landlab.grid.unstructured.links import link_count_per_node
>>> link_count_per_node(([0, 1, 2, 3, 4, 5], [3, 4, 5, 6, 7, 8]))
array([1, 1, 1, 2, 2, 2, 1, 1, 1])

link_ids_at_node(node_at_link_ends, number_of_nodes=None)

link_ids_at_node((node0, node1), number_of_nodes=None) Links entering and leaving nodes.

Parameters:

• node0 (sequence of array-like) – Node ID at link start and end.

• node1 (sequence of array-like) – Node ID at link start and end.

• number_of_nodes (int, optional) – Number of nodes in the grid

Returns:

Tuple of link id array and offset into link id array.

Return type:

tuple

Examples

>>> from landlab.grid.unstructured.links import link_ids_at_node
>>> (links, count) = link_ids_at_node(
...     ([0, 1, 2, 3, 4, 5], [3, 4, 5, 6, 7, 8]), number_of_nodes=9
... )
>>> links
array([0, 1, 2, 0, 3, 1, 4, 2, 5, 3, 4, 5])
>>> count
array([1, 1, 1, 2, 2, 2, 1, 1, 1])

link_is_active(status_at_link_ends)

link_is_active((status0, status1)) Check if a link is active.

Links are inactive if they connect two boundary nodes or touch a closed boundary. Otherwise, the link is active.

Parameters:

• status0 (sequence of array-like) – Status at link start and end

• status1 (sequence of array-like) – Status at link start and end

Returns:

Boolean array that indicates if a link is active.

Return type:

ndarray, boolean

out_link_count_per_node(node_at_link_ends, number_of_nodes=0)

out_link_count_per_node((node0, node1), number_of_nodes=0) Number of links leaving nodes.

Parameters:

• node0 (sequence of array-like) – Node ID at link start and end.

• node1 (sequence of array-like) – Node ID at link start and end.

• number_of_nodes (int, optional) – Number of nodes in the grid

Returns:

Number of links leaving nodes.

Return type:

ndarray

Examples

>>> from landlab.grid.unstructured.links import out_link_count_per_node
>>> out_link_count_per_node(([0, 1, 2, 3, 4, 5], [3, 4, 5, 6, 7, 8]))
array([1, 1, 1, 1, 1, 1])
>>> out_link_count_per_node(
...     ([0, 1, 2, 3, 4, 5], [3, 4, 5, 6, 7, 8]), number_of_nodes=9
... )
array([1, 1, 1, 1, 1, 1, 0, 0, 0])

out_link_ids_at_node(node_at_link_ends, link_ids=None, number_of_nodes=None)

out_link_ids_at_node((node0, node1), number_of_nodes=None) Links leaving nodes.

Parameters:

• node0 (sequence of array-like) – Node ID at link start and end.

• node1 (sequence of array-like) – Node ID at link start and end.

• number_of_nodes (int, optional) – Number of nodes in the grid

Returns:

Tuple of link id array and offset into link id array.

Return type:

tuple

Examples

>>> from landlab.grid.unstructured.links import out_link_ids_at_node
>>> (links, count) = out_link_ids_at_node(
...     ([0, 1, 2, 3, 4, 5], [3, 4, 5, 6, 7, 8]),
...     link_ids=range(-1, 5),
...     number_of_nodes=9,
... )
>>> links
array([-1,  0,  1,  2,  3,  4])
>>> count
array([1, 1, 1, 1, 1, 1, 0, 0, 0])

>>> (links, count) = out_link_ids_at_node(
...     ([0, 1, 2, 3, 4, 5], [3, 4, 5, 6, 7, 8]), number_of_nodes=9
... )
>>> links
array([0, 1, 2, 3, 4, 5])
>>> count
array([1, 1, 1, 1, 1, 1, 0, 0, 0])