verde.grid_coordinates

verde.grid_coordinates#

verde.grid_coordinates(region, shape=None, spacing=None, adjust='spacing', pixel_register=False, extra_coords=None, meshgrid=True)[source]#

Generate the coordinates for each point on a regular grid.

The grid can be specified by either the number of points in each dimension (the shape) or by the grid node spacing.

If the given region is not divisible by the desired spacing, either the region or the spacing will have to be adjusted. By default, the spacing will be rounded to the nearest multiple. Optionally, the East and North boundaries of the region can be adjusted to fit the exact spacing given. See the examples below.

Parameters:
regionlist = [W, E, S, N]

The boundaries of a given region in Cartesian or geographic coordinates.

shapetuple = (n_north, n_east) or None

The number of points in the South-North and West-East directions, respectively.

spacingfloat, tuple = (s_north, s_east), or None

The grid spacing in the South-North and West-East directions, respectively. A single value means that the spacing is equal in both directions.

adjust{‘spacing’, ‘region’}

Whether to adjust the spacing or the region if required. Ignored if shape is given instead of spacing. Defaults to adjusting the spacing.

pixel_registerbool

If True, the coordinates will refer to the center of each grid pixel instead of the grid lines. In practice, this means that there will be one less element per dimension of the grid when compared to grid line registered (only if given spacing and not shape). Default is False.

extra_coordsNone, scalar or list

If not None, then value(s) of extra coordinate arrays to be generated. These extra arrays will have the same shape as the others but will contain a constant value. Will generate an extra array per value given in extra_coords. Use this to generate arrays of constant heights or times, for example, that might be needed to evaluate a gridder.

meshgridbool

If True, will call numpy.meshgrid on the generated coordinates and return 2D arrays (useful if you need the coordinate values for every single point on a grid). Otherwise, will return 1D coordinate arrays (useful if you’re making a xarray.DataArray or looping over grid coordinates with two for loops). Passing False to meshgrid is incompatible with *extra_coords* and an exception will be raised if used together (ValueError).

Returns:
coordinatestuple of arrays

Arrays with coordinates of each point in the grid. Each array contains values for a dimension in the order: easting, northing, vertical, and any extra dimensions given in extra_coords. All arrays will have the specified shape.

See also

scatter_points

Generate the coordinates for a random scatter of points

profile_coordinates

Coordinates for a profile between two points

line_coordinates

Generate evenly spaced points between two values

Examples

>>> east, north = grid_coordinates(region=(0, 5, 0, 10), shape=(5, 3))
>>> print(east.shape, north.shape)
(5, 3) (5, 3)
>>> print(east)
[[0.  2.5 5. ]
 [0.  2.5 5. ]
 [0.  2.5 5. ]
 [0.  2.5 5. ]
 [0.  2.5 5. ]]
>>> print(north)
[[ 0.   0.   0. ]
 [ 2.5  2.5  2.5]
 [ 5.   5.   5. ]
 [ 7.5  7.5  7.5]
 [10.  10.  10. ]]

The grid can also be specified using the spacing between points instead of the shape:

>>> east, north = grid_coordinates(region=(0, 5, 0, 10), spacing=2.5)
>>> print(east.shape, north.shape)
(5, 3) (5, 3)
>>> print(east)
[[0.  2.5 5. ]
 [0.  2.5 5. ]
 [0.  2.5 5. ]
 [0.  2.5 5. ]
 [0.  2.5 5. ]]
>>> print(north)
[[ 0.   0.   0. ]
 [ 2.5  2.5  2.5]
 [ 5.   5.   5. ]
 [ 7.5  7.5  7.5]
 [10.  10.  10. ]]

If you don’t need the 2D arrays, then use meshgrid=False:

>>> east, north = grid_coordinates(
...     region=(0, 5, 0, 10), spacing=2.5, meshgrid=False,
... )
>>> print(east.shape, north.shape)
(3,) (5,)
>>> print(east)
[0.  2.5 5. ]
>>> print(north)
[ 0.   2.5  5.   7.5 10. ]

The spacing can be different for northing and easting, respectively:

>>> east, north = grid_coordinates(region=(-5, 1, 0, 10), spacing=(2.5, 1))
>>> print(east.shape, north.shape)
(5, 7) (5, 7)
>>> print(east)
[[-5. -4. -3. -2. -1.  0.  1.]
 [-5. -4. -3. -2. -1.  0.  1.]
 [-5. -4. -3. -2. -1.  0.  1.]
 [-5. -4. -3. -2. -1.  0.  1.]
 [-5. -4. -3. -2. -1.  0.  1.]]
>>> print(north)
[[ 0.   0.   0.   0.   0.   0.   0. ]
 [ 2.5  2.5  2.5  2.5  2.5  2.5  2.5]
 [ 5.   5.   5.   5.   5.   5.   5. ]
 [ 7.5  7.5  7.5  7.5  7.5  7.5  7.5]
 [10.  10.  10.  10.  10.  10.  10. ]]

If the region can’t be divided into the desired spacing, the spacing will be adjusted to conform to the region:

>>> east, north = grid_coordinates(region=(-5, 0, 0, 5), spacing=2.6)
>>> print(east.shape, north.shape)
(3, 3) (3, 3)
>>> print(east)
[[-5.  -2.5  0. ]
 [-5.  -2.5  0. ]
 [-5.  -2.5  0. ]]
>>> print(north)
[[0.  0.  0. ]
 [2.5 2.5 2.5]
 [5.  5.  5. ]]
>>> east, north = grid_coordinates(region=(-5, 0, 0, 5), spacing=2.4)
>>> print(east.shape, north.shape)
(3, 3) (3, 3)
>>> print(east)
[[-5.  -2.5  0. ]
 [-5.  -2.5  0. ]
 [-5.  -2.5  0. ]]
>>> print(north)
[[0.  0.  0. ]
 [2.5 2.5 2.5]
 [5.  5.  5. ]]

You can choose to adjust the East and North boundaries of the region instead:

>>> east, north = grid_coordinates(region=(-5, 0, 0, 5), spacing=2.6,
...                                adjust='region')
>>> print(east.shape, north.shape)
(3, 3) (3, 3)
>>> print(east)
[[-5.  -2.4  0.2]
 [-5.  -2.4  0.2]
 [-5.  -2.4  0.2]]
>>> print(north)
[[0.  0.  0. ]
 [2.6 2.6 2.6]
 [5.2 5.2 5.2]]
>>> east, north = grid_coordinates(region=(-5, 0, 0, 5), spacing=2.4,
...                                adjust='region')
>>> print(east.shape, north.shape)
(3, 3) (3, 3)
>>> print(east)
[[-5.  -2.6 -0.2]
 [-5.  -2.6 -0.2]
 [-5.  -2.6 -0.2]]
>>> print(north)
[[0.  0.  0. ]
 [2.4 2.4 2.4]
 [4.8 4.8 4.8]]

We can optionally generate coordinates for the center of each grid pixel instead of the corner (default):

>>> east, north = grid_coordinates(region=(0, 5, 0, 10), spacing=2.5,
...                                pixel_register=True)
>>> # Notice that the shape is 1 less than when pixel_register=False
>>> print(east.shape, north.shape)
(4, 2) (4, 2)
>>> print(east)
[[1.25 3.75]
 [1.25 3.75]
 [1.25 3.75]
 [1.25 3.75]]
>>> print(north)
[[1.25 1.25]
 [3.75 3.75]
 [6.25 6.25]
 [8.75 8.75]]
>>> east, north = grid_coordinates(region=(0, 5, 0, 10), shape=(4, 2),
...                                pixel_register=True)
>>> print(east)
[[1.25 3.75]
 [1.25 3.75]
 [1.25 3.75]
 [1.25 3.75]]
>>> print(north)
[[1.25 1.25]
 [3.75 3.75]
 [6.25 6.25]
 [8.75 8.75]]

Generate arrays for other coordinates that have a constant value:

>>> east, north, height = grid_coordinates(
...     region=(0, 5, 0, 10), spacing=2.5, extra_coords=57
... )
>>> print(east.shape, north.shape, height.shape)
(5, 3) (5, 3) (5, 3)
>>> print(height)
[[57. 57. 57.]
 [57. 57. 57.]
 [57. 57. 57.]
 [57. 57. 57.]
 [57. 57. 57.]]
>>> east, north, height, time = grid_coordinates(
...     region=(0, 5, 0, 10), spacing=2.5, extra_coords=[57, 0.1]
... )
>>> print(east.shape, north.shape, height.shape, time.shape)
(5, 3) (5, 3) (5, 3) (5, 3)
>>> print(height)
[[57. 57. 57.]
 [57. 57. 57.]
 [57. 57. 57.]
 [57. 57. 57.]
 [57. 57. 57.]]
>>> print(time)
[[0.1 0.1 0.1]
 [0.1 0.1 0.1]
 [0.1 0.1 0.1]
 [0.1 0.1 0.1]
 [0.1 0.1 0.1]]

Examples using verde.grid_coordinates#

Mask grid points by convex hull

Mask grid points by convex hull

Mask grid points by distance

Mask grid points by distance

Grid Coordinates

Grid Coordinates

Evaluating Performance

Evaluating Performance

Model Selection

Model Selection