iris.experimental.regrid#

Regridding functions.

Notes

Deprecated since version 3.2.0: This package will be removed in a future release. The PointInCell class has now moved to iris.analysis.PointInCell. All the other content will be withdrawn.

If you still use any of this, please contact the Iris Developers to discuss how to replace it or to retain it.

class iris.experimental.regrid.PointInCell(weights=None)[source]#

Bases: object

Describe the point-in-cell regridding scheme.

This class describes the point-in-cell regridding scheme for use typically with iris.cube.Cube.regrid().

Warning

This class is now disabled.

The functionality has been moved to iris.analysis.PointInCell.

Point-in-cell regridding scheme for regridding over one or more orthogonal coordinates.

Warning

This class is now disabled.

The functionality has been moved to iris.analysis.PointInCell.

class iris.experimental.regrid.ProjectedUnstructuredLinear(projection=None)[source]#

Bases: object

Describe the linear regridding scheme.

This class describes the linear regridding scheme which uses the scipy.interpolate.griddata to regrid unstructured data on to a grid.

The source cube and the target cube will be projected into a common projection for the scipy calculation to be performed.

Linear regridding scheme.

Linear regridding scheme that uses scipy.interpolate.griddata on projected unstructured data.

Parameters:: projection (cartopy.crs instance, optional) – The projection that the scipy calculation is performed in. If None is given, a PlateCarree projection is used. Defaults to None.

Notes

Deprecated since version 3.2.0: This class is scheduled to be removed in a future release, and no replacement is currently planned. If you make use of this functionality, please contact the Iris Developers to discuss how to retain it (which could include reversing the deprecation).

regridder(src_cube, target_grid)[source]#

Create a linear regridder to perform regridding.

Creates a linear regridder to perform regridding, using scipy.interpolate.griddata from unstructured source points to the target grid. The regridding calculation is performed in the given projection.

Typically you should use iris.cube.Cube.regrid() for regridding a cube. There are, however, some situations when constructing your own regridder is preferable. These are detailed in the user guide.

Does not support lazy regridding.

Parameters:

src_cube (Cube) – The Cube defining the unstructured source points.
target_grid (Cube) – The Cube defining the target grid.

Returns:

A callable with the interface:

`callable(cube)`

where cube is a cube with the same grid as src_cube that is to be regridded to the target_grid.

Return type:

callable

class iris.experimental.regrid.ProjectedUnstructuredNearest(projection=None)[source]#

Bases: object

Describe the nearest regridding scheme which uses scipy.interpolate.griddata.

This class describes the nearest regridding scheme which uses the scipy.interpolate.griddata to regrid unstructured data on to a grid.

The source cube and the target cube will be projected into a common projection for the scipy calculation to be performed.

Note

The iris.analysis.UnstructuredNearest scheme performs essentially the same job. That calculation is more rigorously correct and may be applied to larger data regions (including global). This one however, where applicable, is substantially faster.

Nearest regridding scheme that uses scipy.interpolate.griddata on projected unstructured data.

Parameters:: projection (cartopy.crs instance, optional) – The projection that the scipy calculation is performed in. If None is given, a PlateCarree projection is used. Defaults to None.

Notes

Deprecated since version 3.2.0: This class is scheduled to be removed in a future release, and no exact replacement is currently planned. Please use iris.analysis.UnstructuredNearest instead, if possible. If you have a need for this exact functionality, please contact the Iris Developers to discuss how to retain it (which could include reversing the deprecation).

regridder(src_cube, target_grid)[source]#

Create a nearest-neighbour regridder to perform regridding.

Create a nearest-neighbour regridder to perform regridding, using scipy.interpolate.griddata from unstructured source points to the target grid. The regridding calculation is performed in the given projection.

Typically you should use iris.cube.Cube.regrid() for regridding a cube. There are, however, some situations when constructing your own regridder is preferable. These are detailed in the user guide.

Does not support lazy regridding.

Parameters:

src_cube (Cube) – The Cube defining the unstructured source points.
target_grid (Cube) – The Cube defining the target grid.

Returns:

A callable with the interface:

`callable(cube)`

where cube is a cube with the same grid as src_cube that is to be regridded to the target_grid.

Return type:

callable

iris.experimental.regrid.regrid_area_weighted_rectilinear_src_and_grid(src_cube, grid_cube, mdtol=0)[source]#

Regrid using the area weighted mean of data values.

Return a new cube with data values calculated using the area weighted mean of data values from src_grid regridded onto the horizontal grid of grid_cube.

This function requires that the horizontal grids of both cubes are rectilinear (i.e. expressed in terms of two orthogonal 1D coordinates) and that these grids are in the same coordinate system. This function also requires that the coordinates describing the horizontal grids all have bounds.

Parameters:

src_cube (iris.cube.Cube) – An instance of iris.cube.Cube that supplies the data, metadata and coordinates.
grid_cube (iris.cube.Cube) – An instance of iris.cube.Cube that supplies the desired horizontal grid definition.
mdtol (int, default=0) – Tolerance of missing data. The value returned in each element of the returned cube’s data array will be masked if the fraction of masked data in the overlapping cells of the source cube exceeds mdtol. This fraction is calculated based on the area of masked cells within each target cell. mdtol=0 means no missing data is tolerated while mdtol=1 will mean the resulting element will be masked if and only if all the overlapping cells of the source cube are masked. Defaults to 0.

Return type:

A new iris.cube.Cube instance.

Notes

Elements in data array of the returned cube that lie either partially or entirely outside of the horizontal extent of the src_cube will be masked irrespective of the value of mdtol.

Deprecated since version 3.2.0: This function is scheduled to be removed in a future release. Please use iris.cube.Cube.regrid() with the iris.analysis.AreaWeighted scheme instead : this is an exact replacement.

For example :

result = src_cube.regrid(grid_cube, AreaWeighted())

iris.experimental.regrid.regrid_weighted_curvilinear_to_rectilinear(src_cube, weights, grid_cube)[source]#

Regrid using the weighted mean and the weights.

Return a new cube with the data values calculated using the weighted mean of data values from src_cube and the weights from weights regridded onto the horizontal grid of grid_cube.

This function requires that the src_cube has a horizontal grid defined by a pair of X- and Y-axis coordinates which are mapped over the same cube dimensions, thus each point has an individually defined X and Y coordinate value. The actual dimensions of these coordinates are of no significance. The src_cube grid cube must have a normal horizontal grid, i.e. expressed in terms of two orthogonal 1D horizontal coordinates. Both grids must be in the same coordinate system, and the grid_cube must have horizontal coordinates that are both bounded and contiguous.

Note that, for any given target grid_cube cell, only the points from the src_cube that are bound by that cell will contribute to the cell result. The bounded extent of the src_cube will not be considered here.

A target grid_cube cell result will be calculated as, \(\sum (src\_cube.data_{ij} * weights_{ij}) / \sum weights_{ij}\), for all \(ij\) src_cube points that are bound by that cell.

Warning

All coordinates that span the src_cube that don’t define the horizontal curvilinear grid will be ignored.

Parameters:

src_cube (iris.cube.Cube) – A iris.cube.Cube instance that defines the source variable grid to be regridded.
weights (array or None) – A numpy.ndarray instance that defines the weights for the source variable grid cells. Must have the same shape as the X and Y coordinates. If weights is None, all-ones will be used.
grid_cube (iris.cube.Cube) – A iris.cube.Cube instance that defines the target rectilinear grid.

Return type:

A iris.cube.Cube instance.

Notes

Deprecated since version 3.2.0: This function is scheduled to be removed in a future release. Please use iris.cube.Cube.regrid() with the iris.analysis.PointInCell scheme instead : this is an exact replacement.

For example :

result = src_cube.regrid(grid_cube, PointInCell())