cfdm.DomainTopology.to_edge

DomainTopology.to_edge(sort=False, face_nodes=None)[source]

Create a new domain topology of edges.

The edges are defined from the original domain topology, either as sides of faces, or the links between nodes, or copied from the existing edges.

Added in version (cfdm): 1.13.1.0

See also

normalise, sort

Parameters:
sort: bool

If True then sort output edges. This is equivalent to, but faster than, setting sort to False and sorting the returned DomainTopology with its sort method.

face_nodes: None or sequence of int, optional

The unique node ids for ‘face’ cells. If None (the default) then the node ids will be inferred from the data, at some computational expense. The order of the nodes is immaterial. Providing face_nodes is an optimisation in the case that these are known externally.

Warning

No checks are carried out to ensure that the given face_nodes match the actual node ids stored in the data, and a mis-match will result in an exception or, worse, an incorrect result.

Returns:
DomainTopology

The domain topology construct of unique edges.

Examples

>>> f = cfdm.example_field(8)
>>> print(f)
Field: air_temperature (ncvar%ta)
---------------------------------
Data            : air_temperature(time(2), ncdim%nMesh2_face(3)) K
Cell methods    : time(2): point (interval: 3600 s)
Dimension coords: time(2) = [2016-01-02 01:00:00, 2016-01-02 11:00:00] gregorian
Auxiliary coords: longitude(ncdim%nMesh2_face(3)) = [-44.0, -44.0, -42.0] degrees_east
                : latitude(ncdim%nMesh2_face(3)) = [34.0, 32.0, 34.0] degrees_north
Topologies      : cell:face(ncdim%nMesh2_face(3), 4) = [[2, ..., --]]
Connectivities  : connectivity:edge(ncdim%nMesh2_face(3), 5) = [[0, ..., --]]
>>> dt = f[0].domain_topology()
>>> print(dt.array)
[[2 3 1 0]
 [4 5 3 2]
 [6 1 3 --]]
>>> edge = dt.to_edge()
>>> edge
<DomainTopology: cell:edge(9, 2) >
>>> print(edge.array)
[[0 1]
 [2 4]
 [2 3]
 [0 2]
 [4 5]
 [3 6]
 [1 6]
 [1 3]
 [3 5]]
>>> print(dt.to_edge(sort=True).array)
[[0 1]
 [0 2]
 [1 3]
 [1 6]
 [2 3]
 [2 4]
 [3 5]
 [3 6]
 [4 5]]

>>> f = cfdm.example_field(10)
>>> print(f)
Field: air_pressure (ncvar%pa)
------------------------------
Data            : air_pressure(time(2), ncdim%nMesh2_node(7)) hPa
Cell methods    : time(2): point (interval: 3600 s)
Dimension coords: time(2) = [2016-01-02 01:00:00, 2016-01-02 11:00:00] gregorian
Auxiliary coords: longitude(ncdim%nMesh2_node(7)) = [-45.0, ..., -40.0] degrees_east
                : latitude(ncdim%nMesh2_node(7)) = [35.0, ..., 34.0] degrees_north
Topologies      : cell:point(ncdim%nMesh2_node(7), 5) = [[0, ..., --]]
>>> dt = f[0].domain_topology()
>>> print(dt.array)
[[0 1 2 -- --]
 [1 6 0 3 --]
 [2 0 3 4 --]
 [3 2 1 5 6]
 [4 2 5 -- --]
 [5 4 3 -- --]
 [6 3 1 -- --]]
>>> dt.to_edge()
<DomainTopology: cell:edge(9, 2) >
>>> print(dt.to_edge(sort=True).array)
[[0 1]
 [0 2]
 [1 3]
 [1 6]
 [2 3]
 [2 4]
 [3 5]
 [3 6]
 [4 5]]