def calculate_gradients_at_links(grid, node_values, out=None):
"""Calculate gradients over links.
Construction::
calculate_gradients_at_links(grid, node_values, out=None)
Parameters
----------
grid : RasterModelGrid
A grid.
node_values : array_like or field name
Values at nodes.
out : ndarray, optional
Buffer to hold result. If `None`, create a new array.
Returns
-------
ndarray
Gradients of the nodes values for each link.
Examples
--------
>>> from landlab import RasterModelGrid
>>> grid = RasterModelGrid((3, 3))
>>> node_values = [0., 0., 0.,
... 1., 3., 1.,
... 2., 2., 2.]
>>> grid.calculate_gradients_at_links(node_values)
array([ 0., 0., 1., 3., 1., 2., -2., 1., -1., 1., 0., 0.])
>>> out = np.empty(grid.number_of_links, dtype=float)
>>> rtn = grid.calculate_gradients_at_links(node_values, out=out)
>>> rtn is out
True
>>> out
array([ 0., 0., 1., 3., 1., 2., -2., 1., -1., 1., 0., 0.])
>>> grid = RasterModelGrid((3, 3), spacing=(1, 2))
>>> grid.calculate_gradients_at_links(node_values)
array([ 0., 0., 1., 3., 1., 1., -1., 1., -1., 1., 0., 0.])
>>> _ = grid.add_field('node', 'elevation', node_values)
>>> grid.calculate_gradients_at_links('elevation')
array([ 0., 0., 1., 3., 1., 1., -1., 1., -1., 1., 0., 0.])
"""
grads = gradients.calculate_diff_at_links(grid, node_values, out=out)
grads /= grid.link_length
# n_vertical_links = (grid.shape[0] - 1) * grid.shape[1]
# diffs[:n_vertical_links] /= grid.dy
# diffs[n_vertical_links:] /= grid.dx
return grads
def calculate_gradients_at_links(grid, node_values, out=None):
"""Calculate gradients over links.
Construction::
calculate_gradients_at_links(grid, node_values, out=None)
Parameters
----------
grid : RasterModelGrid
A grid.
node_values : array_like or field name
Values at nodes.
out : ndarray, optional
Buffer to hold result. If `None`, create a new array.
Returns
-------
ndarray
Gradients of the nodes values for each link.
Examples
--------
>>> from landlab import RasterModelGrid
>>> grid = RasterModelGrid((3, 3))
>>> node_values = [0., 0., 0.,
... 1., 3., 1.,
... 2., 2., 2.]
>>> grid.calculate_gradients_at_links(node_values)
array([ 0., 0., 1., 3., 1., 2., -2., 1., -1., 1., 0., 0.])
>>> out = np.empty(grid.number_of_links, dtype=float)
>>> rtn = grid.calculate_gradients_at_links(node_values, out=out)
>>> rtn is out
True
>>> out
array([ 0., 0., 1., 3., 1., 2., -2., 1., -1., 1., 0., 0.])
>>> grid = RasterModelGrid((3, 3), spacing=(1, 2))
>>> grid.calculate_gradients_at_links(node_values)
array([ 0., 0., 1., 3., 1., 1., -1., 1., -1., 1., 0., 0.])
>>> _ = grid.add_field('node', 'elevation', node_values)
>>> grid.calculate_gradients_at_links('elevation')
array([ 0., 0., 1., 3., 1., 1., -1., 1., -1., 1., 0., 0.])
"""
grads = gradients.calculate_diff_at_links(grid, node_values, out=out)
grads /= grid.link_length
# n_vertical_links = (grid.shape[0] - 1) * grid.shape[1]
# diffs[:n_vertical_links] /= grid.dy
# diffs[n_vertical_links:] /= grid.dx
return grads
def calculate_gradients_at_links(grid, node_values, out=None):
"""Calculate gradients over links.
Parameters
----------
grid : RasterModelGrid
A grid.
node_values : array_like
Values at nodes.
out : ndarray, optional
Buffer to hold result. If `None`, create a new array.
Returns
-------
ndarray
Gradients of the nodes values for each link.
.. deprecated:: 0.1
Use :func:`calculate_gradient_across_cell_faces`
or :func:`calculate_gradient_across_cell_corners` instead
Examples
--------
>>> from landlab import RasterModelGrid
>>> grid = RasterModelGrid((3, 3))
>>> node_values = [0., 0., 0.,
... 1., 3., 1.,
... 2., 2., 2.]
>>> grid.calculate_gradients_at_links(node_values)
array([ 1., 3., 1., 1., -1., 1., 0., 0., 2., -2., 0., 0.])
>>> out = np.empty(grid.number_of_links, dtype=float)
>>> rtn = grid.calculate_gradients_at_links(node_values, out=out)
>>> rtn is out
True
>>> out
array([ 1., 3., 1., 1., -1., 1., 0., 0., 2., -2., 0., 0.])
>>> grid = RasterModelGrid((3, 3), spacing=(1, 2))
>>> grid.calculate_gradients_at_links(node_values)
array([ 1., 3., 1., 1., -1., 1., 0., 0., 1., -1., 0., 0.])
>>> _ = grid.add_field('node', 'elevation', node_values)
>>> grid.calculate_gradients_at_links('elevation')
array([ 1., 3., 1., 1., -1., 1., 0., 0., 1., -1., 0., 0.])
"""
diffs = gradients.calculate_diff_at_links(grid, node_values, out=out)
n_vertical_links = (grid.shape[0] - 1) * grid.shape[1]
diffs[:n_vertical_links] /= grid.dy
diffs[n_vertical_links:] /= grid.dx
return diffs
def calculate_gradients_at_links(grid, node_values, out=None):
"""Calculate gradients over links.
Parameters
----------
grid : RasterModelGrid
A grid.
node_values : array_like
Values at nodes.
out : ndarray, optional
Buffer to hold result. If `None`, create a new array.
Returns
-------
ndarray
Gradients of the nodes values for each link.
Examples
--------
>>> from landlab import RasterModelGrid
>>> grid = RasterModelGrid((3, 3))
>>> node_values = [0., 0., 0., 1., 3., 1., 2., 2., 2.]
>>> grid.calculate_gradients_at_links(node_values)
array([ 1., 3., 1., 1., -1., 1., 0., 0., 2., -2., 0., 0.])
>>> out = np.empty(grid.number_of_links, dtype=float)
>>> rtn = grid.calculate_gradients_at_links(node_values, out=out)
>>> rtn is out
True
>>> out
array([ 1., 3., 1., 1., -1., 1., 0., 0., 2., -2., 0., 0.])
.. deprecated:: 0.1
Use :func:`calculate_gradient_across_cell_faces`
or :func:`calculate_gradient_across_cell_corners` instead
"""
diffs = gradients.calculate_diff_at_links(grid, node_values, out=out)
return np.divide(diffs, grid.node_spacing, out=diffs)
