unifhy.BritishNationalGrid.cell_area

BritishNationalGrid.cell_area

The horizontal area for the grid cells of the SpaceDomain in square metres given as a cf.Field and returned as a numpy.ndarray.

Parameters

areas: cf.Field

The field containing the horizontal grid cell area. The shape of the data array must be the same as the SpaceDomain. The field data must contain surface area values in square metres.

Returns

numpy.ndarray

The array containing the horizontal grid cell area values in square metres. If not set previously, computed automatically.

Examples

Retrieving automatically computed grid cell area:

>>> grid = BritishNationalGrid.from_extent_and_resolution(
...     projection_y_coordinate_extent=(12000, 15000),
...     projection_y_coordinate_resolution=1000,
...     projection_x_coordinate_extent=(80000, 84000),
...     projection_x_coordinate_resolution=2000
... )
>>> print(grid.cell_area)
[[2000000. 2000000.]
 [2000000. 2000000.]
 [2000000. 2000000.]]
>>> print(grid)
BritishNationalGrid(
    shape {Y, X}: (3, 2)
    Y, projection_y_coordinate (3,): [12500.0, 13500.0, 14500.0] m
    X, projection_x_coordinate (2,): [81000.0, 83000.0] m
    Y_bounds (3, 2): [[12000.0, ..., 15000.0]] m
    X_bounds (2, 2): [[80000.0, ..., 84000.0]] m
    cell_area (3, 2): [[2000000.0, ..., 2000000.0]] m2
)

Manually assigning grid cell area values:

>>> import numpy
>>> areas = grid.to_field()
>>> areas.set_data(numpy.array([[1999999, 1999999],
...                             [1999999, 1999999],
...                             [1999999, 1999999]]))
>>> areas.units = 'm2'
>>> grid.cell_area = areas
>>> print(grid.cell_area)
[[1999999. 1999999.]
 [1999999. 1999999.]
 [1999999. 1999999.]]