tri_grid

class gridkit.tri_grid.TriGrid(*args, size=None, area=None, side_length=None, offset=(0, 0), rotation=0, **kwargs)[source]

Bases: BaseGrid

Abstraction that represents an infinite grid with cells in the shape of equilateral triangles.

The size of each cell can be specified through the size or area arguments.

Initialization parameters

size: float

The spacing between two cell centroids in horizontal direction. Cannot be supplied together with area or ‘side_length’.

area: float

The area of a cell. Cannot be supplied together with size or ‘side_length’.

side_length: float

The length of the sides of a cell, which is 1/6th the cell outline. . Cannot be supplied together with area or ‘size’.

offset: Tuple(float, float) (optional)

The offset in dx and dy. Shifts the whole grid by the specified amount. The shift is always reduced to be maximum one cell size. If the supplied shift is larger, a shift will be performed such that the new center is a multiple of dx or dy away. Default: (0,0)

rotation: float

The counter-clockwise rotation of the grid around the origin in degrees.

crs: pyproj.CRS (optional)

The coordinate reference system of the grid. The value can be anything accepted by pyproj.CRS.from_user_input(), such as an epsg integer (eg 4326), an authority string (eg “EPSG:4326”) or a WKT string. Default: None

See also

RectGrid, HexGrid, BoundedTriGrid

property definition

The parameters that define the infinite grid. Passing these parameters into a new object instance will create a perfectly aligned grid. Note that Bounded Grids are defined by the bounds and data. Therefore, the properties returned by this property do describe the grid but cannot be used to create a new Bounded Grid object instance.

Returns:

A dictionary outlying the parameters that define the grid

Return type:

dict

property dx: float

The spacing between cell centers in x-direction

property dy: float

The spacing between cell centers in y-direction

property r: float

The radius of the cell. The radius is defined to be the distance from the cell center to a cell corner.

property side_length

The lenght of the side of a cell. The length is the same as 2 * HexGrid.dx().

centroid(index)[source]

Coordinates at the center of the cell(s) specified by index.

If this method is called on a ‘Bounded’ class, the index argument is optional. In such a case the cell IDs of the cells contained in the Bounded product are returned.

Parameters:

index (GridIndex) – The index of the cell(s) of which the centroid is to be obtained.

Returns:

Multidimensional array containing the longitude and latitude of the center of each cell respectively, in (width, height, lonlat)

Return type:

numpy.ndarray

Raises:

ValueError – No index parameter was supplied to a grid that does not contain data.

cell_corners(index=None)[source]

Coordinates of the cell corners as specified by index.

Parameters:

index (GridIndex) – The indices of the cells of interest. Each id contains an x and y value.

Returns:

An array of coordinates in (x,y) specifying each of the corners. The returned array will be of the same shape as the input index, but with an extra axis containing the corners. The last axis is always of size 2 (x,y). The second to last axis is the length of the corners. The other axis are in the shape of the supplied index.

Return type:

numpy.ndarray

cell_at_point(point)[source]

Determine the ID of the cell in which point falls.

Parameters:

point (tuple) – The coordinates of the point to which to match the cell

Returns:

The ID of the cell in (x,y)

Return type:

tuple

cells_in_bounds(bounds, return_cell_count=False)[source]

Cells contained within a bounding box.

Parameters:

  • bounds (tuple) – The bounding box in which to find the cells in (min_x, min_y, max_x, max_y)

  • return_cell_count (bool) – Return a tuple containing the nr of cells in x and y direction inside the provided bounds

Returns:

The indices of the cells contained in the bounds

Return type:

GridIndex

cells_near_point(point)[source]

The cells nearest to a point, often used in interpolation at the location of the point. For a TriGrid there are 6 nearby points. For a HexGrid there are 3 nearby points. For a RectGrid there are 4 nearby points.

subdivide(factor: int)[source]

Create a new grid that is factor times smaller than the existing grid and aligns perfectly with it.

If factor is one, the side lengths of the new cells will be of the same size as the side lengths of the original cells, which means that the two grids will be exactly the same. If factor is two, the new cell sides will be half the size of the original cell sides. The number of cells grows quadratically with factor. A factor of 2 results in 4 cells that fit in the original, a factor of 3 results in 9 cells that fit in the original, etc..

Parameters:

factor (int) – An integer (whole number) indicating how many times smaller the new gridsize will be. It refers to the side of a grid cell. If factor is 1, the new grid will have cell sides of the same length as the cell sides of the original. If factor is 2, the side of the grid cell will be half the cell side length of the original.

Returns:

A new grid that is factor times smaller then the original grid.

Return type:

TriGrid

is_cell_upright(index)[source]

Whether the selected cell points up or down. True if the cell points up, False if the cell points down.

Parameters:

index (GridIndex) – The index of the cell(s) of interest

Returns:

A boolean value reflecting whether the cell is upright or not. Or a 1d array containing the boolean values for each cell.

Return type:

numpy.ndarray or bool

property parent_grid_class
relative_neighbours(index=None, depth=1, connect_corners=False, include_selected=False)[source]

The relative indices of the neighbouring cells.

Parameters:

  • depth (int Default: 1) – Determines the number of neighbours that are returned. If depth=1 the direct neighbours are returned. If depth=2 the direct neighbours are returned, as well as the neighbours of these neighbours. depth=3 returns yet another layer of neighbours, and so forth.

  • index (numpy.ndarray) – The index of the cell of which the relative neighbours are desired. This is mostly relevant because in hexagonal grids the neighbouring indices differ when dealing with odd or even indices.

  • include_selected (bool Default: False) – Whether to include the specified cell in the return array. Even though the specified cell can never be a neighbour of itself, this can be useful when for example a weighted average of the neighbours is desired in which case the cell itself often should also be included.

  • connect_corners (bool Default: False) – Whether to consider cells that touch corners but not sides as neighbours. Each cell has 3 neighbours if connect_corners is False, and 9 neighbours if connect_corners is True.

See also

BaseGrid.neighbours(), RectGrid.relative_neighbours(), HexGrid.relative_neighbours()

neighbours(index=None, depth=1, connect_corners=False, include_selected=False)[source]

The indices of the neighbouring cells. The argument ‘depth’ can be used to include cells from further away.

Parameters:

  • index (numpy.ndarray) – The index of the cell(s) of which to get the neighbours.

  • depth (int Default: 1) – Determines the number of neighbours that are returned. If depth=1 the direct neighbours are returned. If depth=2 the direct neighbours are returned, as well as the neighbours of these neighbours. depth=3 returns yet another layer of neighbours, and so forth.

  • connect_corners (bool Default: False) – Whether to consider cells that touch corners but not sides as neighbours. This does not apply to HexGrid.relative_neighbours(). For further information on this argument, refer to RectGrid.relative_neighbours().

  • include_selected (bool Default: False) – Whether to include the specified cell in the return array. Even though the specified cell can never be a neighbour of itself, this can be useful when for example a weighted average of the neighbours is desired in which case the cell itself often should also be included.

Examples

The direct neighbours of a cell can be returned by using depth=1, which is the default.

>>> from gridkit.rect_grid import RectGrid
>>> grid = RectGrid(dx=2, dy=3)
>>> grid.neighbours([1,2]).index
array([[1, 3],
       [0, 2],
       [2, 2],
       [1, 1]])

For more detailed examples:

See also

RectGrid.relative_neighbours(), HexGrid.relative_neighbours(), TriGrid.relative_neighbours()

to_bounded(bounds, fill_value=nan)[source]

Create a bounded version of this grid where the data in the bounds is filled with the supplied fill_value

Parameters:

  • bounds (tuple) – The bounds of the area of interest in (minx, miny, maxx, maxy). The bounds need to be aligned to the grid. See BaseGrid.align_bounds()

  • fill_value (numpy.dtype (optional)) – The value to assign to the newly created array that fills the supplied bounds. Default: numpy.nan

Returns:

A bounded version of the current grid where the data is filled with fill_value.

Return type:

BoundedHexGrid or BoundedRectGrid

See also

BaseGrid.to_bounded(), RectGrid.to_bounded(), HexGrid.to_bounded()

to_crs(crs, location=(0, 0), adjust_rotation=False)[source]

Transforms the Coordinate Reference System (CRS) from the current CRS to the desired CRS. This will update the cell size and the origin offset.

The crs attribute on the current grid must be set.

Parameters:

crs (Union[int, str, pyproj.CRS]) – The value can be anything accepted by pyproj.CRS.from_user_input(), such as an epsg integer (eg 4326), an authority string (eg “EPSG:4326”) or a WKT string.

location: (float, float) (default: (0,0))

The location at which to perform the conversion. When transforming to a new coordinate system, it matters at which location the transformation is performed. The chosen location will be used to determinde the cell size of the new grid. If you are unsure what location to use, pich the center of the area you are interested in.

Warning

The location is defined in the original CRS, not in the CRS supplied as the argument to this function call.

adjust_rotation: bool (default: False)

If False, the grid in the new crs has the same rotation as the original grid. Since coordinate transformations often warp and rotate the grid, the original rotation is often not a good fit anymore. If True, set the new rotation to match the orientation of the grid at location after coordinate transformation.

Returns:

A copy of the grid with modified cell spacing to match the specified CRS

Return type:

HexGrid

See also

Examples:

Example: coordinate transformations

Methods:

RectGrid.to_crs() BoundedTriGrid.to_crs() BoundedHexGrid.to_crs()

anchor(target_loc: Tuple[float, float], cell_element: Literal['centroid', 'corner'] = 'centroid', in_place: bool = False)[source]

Position a specified part of a grid cell at a specified location. This shifts (the origin of) the grid such that the specified cell_element is positioned at the specified target_loc. This is useful for example to align two grids by anchoring them to the same location.

Parameters:

  • target_loc (Tuple[float, float]) – The coordinates of the point at which to anchor the grid in (x,y)

  • cell_element (Literal["centroid", "corner"] - Default: "centroid") – The part of the cell that is to be positioned at the specified target_loc. Currently only “centroid” and “corner” are supported. When “centroid” is specified, the cell is centered around the target_loc. When “corner” is specified, a nearby cell_corner is placed onto the target_loc.

  • in_place (bool (Default: False)) –

    The original grid instance is modified if in_place is True and no return argument is specified. If in_place is False, the original grid instance remains unchanged and a modified copy is returned.

    Note

    Even though in_place=True saves the creation of a Python object, a new Python object that wraps the Rust implementation needs to be updated and hence a new Python object is still created. Nevertheless, creating one new object is often better than creating two new objects.

Returns:

BaseGrid if in_place=False or None if in_place=True

Return type:

BaseGrid | None

See also

BoundedTriGrid.anchor(), BoundedRectGrid.anchor(), BoundedHexGrid.anchor()

update(size=None, area=None, offset=None, rotation=None, crs=None, **kwargs)[source]

Modify attributes of the existing grid and return a copy. The original grid remains un-mutated.

Parameters:

  • size (float) – The new spacing between cell centers in x-direction. Cannot be supplied together with area.

  • area (float) – The area of a cell. Cannot be supplied together with size.

  • offset (Tuple[float, float]) – The new offset of the origin of the grid

  • rotation (float) – The new counter-clockwise rotation of the grid in degrees. Can be negative for clockwise rotation.

  • crs (Union[int, str, pyproj.CRS]) – The value can be anything accepted by pyproj.CRS.from_user_input(), such as an epsg integer (eg 4326), an authority string (eg “EPSG:4326”) or a WKT string.

Returns:

A modified copy of the current grid

Return type:

RectGrid

class gridkit.tri_grid.BoundedTriGrid(data, *args, bounds=None, **kwargs)[source]

Bases: BoundedGrid, TriGrid

A HexGrid with data encapsulated within a bounding box.

Initialization parameters

data: numpy.ndarray

A 2D ndarray containing the data

bounds: Tuple(float, float, float, float)

The extend of the data in minx, miny, maxx, maxy.

crs: pyproj.CRS (optional)

The coordinate reference system of the grid. The value can be anything accepted by pyproj.CRS.from_user_input(), such as an epsg integer (eg 4326), an authority string (eg “EPSG:4326”) or a WKT string. Default: None

See also

TriGrid, BoundedRectGrid, BoundedHexGrid

centroid(index=None)[source]

Coordinates at the center of the cell(s) specified by index.

If this method is called on a ‘Bounded’ class, the index argument is optional. In such a case the cell IDs of the cells contained in the Bounded product are returned.

Parameters:

index (GridIndex) – The index of the cell(s) of which the centroid is to be obtained.

Returns:

Multidimensional array containing the longitude and latitude of the center of each cell respectively, in (width, height, lonlat)

Return type:

numpy.ndarray

Raises:

ValueError – No index parameter was supplied to a grid that does not contain data.

intersecting_cells(other)[source]
crop(new_bounds, bounds_crs=None, buffer_cells=0)[source]

Cut out a slice of data contained within the supplied bounds.

Parameters:

  • new_bounds (Tuple(minx, miny, maxx, maxy)) – The bounds defining the area to crop, in (minx, miny, maxx, maxy).

  • bounds_crs (pyproj.CRS (optional)) – The bounds defining the extent of the cropped data. The value can be anything accepted by pyproj.CRS.from_user_input().

Returns:

A BoundedGrid containing the data included in the cropped area contained within the bounds.

Return type:

class: BoundedGrid

cell_corners(index: ndarray = None) → ndarray[source]

Coordinates of the cell corners as specified by index.

Parameters:

index (GridIndex) – The indices of the cells of interest. Each id contains an x and y value.

Returns:

An array of coordinates in (x,y) specifying each of the corners. The returned array will be of the same shape as the input index, but with an extra axis containing the corners. The last axis is always of size 2 (x,y). The second to last axis is the length of the corners. The other axis are in the shape of the supplied index.

Return type:

numpy.ndarray

to_shapely(index=None, as_multipolygon: bool = False)[source]

Refer to parent method BaseGrid.to_shapely()

Difference with parent method:

index is optional. If index is None (default) the cells containing data are used as the index argument.

See also

BaseGrid.to_shapely(), BoundedHexGrid.to_shapely()

to_crs(crs, resample_method='nearest')[source]

Transforms the Coordinate Reference System (CRS) from the current CRS to the desired CRS. This will modify the cell size and the bounds accordingly.

The crs attribute on the current grid must be set.

Parameters:

  • crs (Union[int, str, pyproj.CRS]) – The value can be anything accepted by pyproj.CRS.from_user_input(), such as an epsg integer (eg 4326), an authority string (eg “EPSG:4326”) or a WKT string.

  • resample_method (str) – The resampling method to be used for BoundedGrid.resample().

Returns:

A copy of the grid with modified cell spacing and bounds to match the specified CRS

Return type:

BoundedTriGrid

See also

Examples:

Example: coordinate transformations

Methods:

RectGrid.to_crs() HexGrid.to_crs() BoundedHexGrid.to_crs()

anchor(target_loc: Tuple[float, float], cell_element: Literal['centroid', 'corner'] = 'centroid', resample_method='nearest')[source]

Position a specified part of a grid cell at a specified location. This shifts (the origin of) the grid such that the specified cell_element is positioned at the specified target_loc. This is useful for example to align two grids by anchoring them to the same location. The data values for the new grid will need to be resampled since it has been shifted.

Parameters:

  • target_loc (Tuple[float, float]) – The coordinates of the point at which to anchor the grid in (x,y)

  • cell_element (Literal["centroid", "corner"] - Default: "centroid") – The part of the cell that is to be positioned at the specified target_loc. Currently only “centroid” and “corner” are supported. When “centroid” is specified, the cell is centered around the target_loc. When “corner” is specified, a nearby cell_corner is placed onto the target_loc.

  • resample_method (str) – The resampling method to be used for BoundedGrid.resample().

Returns:

The shifted and resampled grid

Return type:

BoundedGrid

See also

BaseGrid.anchor()

numpy_id_to_grid_id(np_index)[source]
grid_id_to_numpy_id(index)[source]
argmax(*args, **kwargs)
argmin(*args, **kwargs)
max(*args, **kwargs)
mean(*args, **kwargs)
median(*args, **kwargs)
min(*args, **kwargs)
std(*args, **kwargs)
sum(*args, **kwargs)