spatial.GeometryFM2D

spatial.GeometryFM2D(
    self,
    node_coordinates,
    element_table,
    codes=None,
    projection='LONG/LAT',
    dfsu_type=DfsuFileType.Dfsu2D,
    element_ids=None,
    node_ids=None,
    validate=True,
    reindex=False,
)

Attributes

Name	Description
boundary_codes	Unique list of boundary codes.
boundary_polylines	Lists of closed polylines defining domain outline.
codes	Node codes of all nodes (0=water, 1=land, 2…=open boundaries).
element_coordinates	Center coordinates of each element.
is_2d	Type is either mesh or Dfsu2D (2 horizontal dimensions).
is_geo	Are coordinates geographical (LONG/LAT)?
is_layered	Type is layered dfsu (3d, vertical profile or vertical column).
is_local_coordinates	Are coordinates relative (NON-UTM)?
is_spectral	Type is spectral dfsu (point, line or area spectrum).
is_tri_only	Does the mesh consist of triangles only.
max_nodes_per_element	The maximum number of nodes for an element.
n_elements	Number of elements.
n_nodes	Number of nodes.
projection	The projection.
projection_string	The projection string.
type_name	Type name, e.g. Mesh, Dfsu2D.

Methods

Name	Description
contains	Test if a list of points are contained by mesh.
find_index	Find a set of element indicies for a number of points or within an area.
find_nearest_elements	Find index of nearest elements (optionally for a list).
get_2d_interpolant	IDW interpolant for list of coordinates.
get_element_area	Calculate the horizontal area of each element.
get_node_centered_data	Convert cell-centered data to node-centered by pseudo-laplacian method.
get_overset_grid	Get a 2d grid that covers the domain by specifying spacing or shape.
interp2d	Interpolate spatially in data (2d only).
isel	Export a selection of elements to a new geometry.
to_mesh	Export geometry to new mesh file.
to_shapely	Export mesh as shapely MultiPolygon.

contains

spatial.GeometryFM2D.contains(points)

Test if a list of points are contained by mesh.

Parameters

Name	Type	Description	Default
points	array-like n-by-2	x,y-coordinates of n points to be tested	required

Returns

Name	Type	Description
	bool array	True for points inside, False otherwise

find_index

spatial.GeometryFM2D.find_index(x=None, y=None, coords=None, area=None)

Find a set of element indicies for a number of points or within an area.

The returned indices returned are the unique, unordered set of element indices that contain the points or area.

This method will return elements containing the argument points/area, which is not necessarily the same as the nearest.

Typically not called directly, but by Dataset/DataArray’s sel() method.

Parameters

Name	Type	Description	Default
x	float | np.ndarray | None	X coordinate(s) (easting or longitude)	None
y	float | np.ndarray | None	Y coordinate(s) (northing or latitude)	None
coords	np.array(float, float)	As an alternative to specifying x, and y individually, the argument coords can be used instead. (x,y)-coordinates of points to be found, by default None	None
area	(float, float, float, float)	Bounding box of coordinates (left lower and right upper) to be selected, by default None	None

Returns

Name	Type	Description
	np.array	indicies of containing elements

Raises

Name	Type	Description
	ValueError	if any point is outside the domain

Examples

>>> g = dfs.geometry
>>> id = dfs.find_index(x=3.1, y=4.3)

See Also

isel : get subset geometry for specific indicies find_nearest_elements : find nearest instead of containing elements

find_nearest_elements

spatial.GeometryFM2D.find_nearest_elements(
    x,
    y=None,
    n_nearest=1,
    return_distances=False,
)

Find index of nearest elements (optionally for a list).

Parameters

Name	Type	Description	Default
x	float | np.ndarray	X coordinate(s) (easting or longitude)	required
y	float | np.ndarray | None	Y coordinate(s) (northing or latitude)	None
n_nearest	int	return this many (horizontally) nearest points for each coordinate set, default=1	1
return_distances	bool	should the horizontal distances to each point be returned? default=False	False

Returns

Name	Type	Description
	np.array	element ids of nearest element(s)
	(np.array, optional)	horizontal distances

Examples

>>> g = dfs.geometry
>>> id = g.find_nearest_elements(3, 4)
>>> ids = g.find_nearest_elements([3, 8], [4, 6])
>>> ids = g.find_nearest_elements(xy)
>>> ids = g.find_nearest_elements(3, 4, n_nearest=4)
>>> ids, d = g.find_nearest_elements(xy, return_distances=True)

See Also

find_index : find element indicies for points or an area

get_2d_interpolant

spatial.GeometryFM2D.get_2d_interpolant(
    xy,
    n_nearest=5,
    extrapolate=False,
    p=2,
    radius=None,
)

IDW interpolant for list of coordinates.

Parameters

Name	Type	Description	Default
xy	array - like	x,y coordinates of new points	required
n_nearest	int	number of nearest elements used for IDW, by default 5	5
extrapolate	bool	allow extrapolation, by default False	False
p	float	power of inverse distance weighting, default=2	2
radius	float | None	an alternative to extrapolate=False, only include elements within radius	None

Returns

Name	Type	Description
	(np.array, np.array)	element ids and weights

get_element_area

spatial.GeometryFM2D.get_element_area()

Calculate the horizontal area of each element.

Returns

Name	Type	Description
	np.array(float)	areas in m2

get_node_centered_data

spatial.GeometryFM2D.get_node_centered_data(data, extrapolate=True)

Convert cell-centered data to node-centered by pseudo-laplacian method.

Parameters

Name	Type	Description	Default
data	np.array(float)	cell-centered data	required
extrapolate	bool	allow the method to extrapolate, default:True	True

Returns

Name	Type	Description
	np.array(float)	node-centered data

get_overset_grid

spatial.GeometryFM2D.get_overset_grid(
    dx=None,
    dy=None,
    nx=None,
    ny=None,
    buffer=0.0,
)

Get a 2d grid that covers the domain by specifying spacing or shape.

Parameters

Name	Type	Description	Default
dx	float or (float, float)	grid resolution in x-direction (or in x- and y-direction)	None
dy	float	grid resolution in y-direction	None
nx	int	number of points in x-direction, by default None, (the value will be inferred)	None
ny	int	number of points in y-direction, by default None, (the value will be inferred)	None
buffer	float	positive to make the area larger, default=0 can be set to a small negative value to avoid NaN values all around the domain.	0.0

Returns

Name	Type	Description
	<mikeio.Grid2D>	2d grid

interp2d

spatial.GeometryFM2D.interp2d(data, elem_ids, weights=None, shape=None)

Interpolate spatially in data (2d only).

Parameters

Name	Type	Description	Default
data	ndarray or list(ndarray)	dfsu data	required
elem_ids	ndarray(int)	n sized array of 1 or more element ids used for interpolation	required
weights	ndarray(float)	weights with same size as elem_ids used for interpolation	None
shape	tuple[int, …] | None	reshape output	None

Returns

Name	Type	Description
	ndarray or list(ndarray)	spatially interped data

Examples

>>> ds = dfsu.read()
>>> g = dfs.get_overset_grid(shape=(50,40))
>>> elem_ids, weights = dfs.get_2d_interpolant(g.xy)
>>> dsi = dfs.interp2d(ds, elem_ids, weights)

isel

spatial.GeometryFM2D.isel(idx, keepdims=False, **kwargs)

Export a selection of elements to a new geometry.

Typically not called directly, but by Dataset/DataArray’s isel() or sel() methods.

Parameters

Name	Type	Description	Default
idx	list(int)	collection of element indicies	required
keepdims	bool	Should the original Geometry type be kept (keepdims=True) or should it be reduced e.g. to a GeometryPoint2D if possible (keepdims=False), by default False	False
**kwargs	Any	Not used	{}

Returns

Name	Type	Description
	Geometry	geometry subset

See Also

find_index : find element indicies for points or an area

to_mesh

spatial.GeometryFM2D.to_mesh(outfilename)

Export geometry to new mesh file.

Parameters

Name	Type	Description	Default
outfilename	str	path to file to be written	required

to_shapely

spatial.GeometryFM2D.to_shapely()

Export mesh as shapely MultiPolygon.

Returns

Name	Type	Description
	shapely.geometry.MultiPolygon	polygons with mesh elements