def _get_plot_defn(cube, mode, ndims=2):
"""
Return data and plot-axis coords given a cube & a mode of either
POINT_MODE or BOUND_MODE.
"""
if cube.ndim != ndims:
msg = 'Cube must be %s-dimensional. Got %s dimensions.'
raise ValueError(msg % (ndims, cube.ndim))
# Start by taking the DimCoords from each dimension.
coords = [None] * ndims
for dim_coord in cube.dim_coords:
dim = cube.coord_dims(dim_coord)[0]
coords[dim] = dim_coord
# When appropriate, restrict to 1D with bounds.
if mode == iris.coords.BOUND_MODE:
coords = list(map(_valid_bound_coord, coords))
def guess_axis(coord):
axis = None
if coord is not None:
axis = iris.util.guess_coord_axis(coord)
return axis
# Allow DimCoords in aux_coords to fill in for missing dim_coords.
for dim, coord in enumerate(coords):
if coord is None:
aux_coords = cube.coords(dimensions=dim)
aux_coords = [coord for coord in aux_coords
if isinstance(coord, iris.coords.DimCoord)]
if aux_coords:
key_func = lambda coord: coord._as_defn()
aux_coords.sort(key=key_func)
coords[dim] = aux_coords[0]
if mode == iris.coords.POINT_MODE:
# Allow multi-dimensional aux_coords to override the dim_coords
# along the Z axis. This results in a preference for using the
# derived altitude over model_level_number or level_height.
# Limit to Z axis to avoid preferring latitude over grid_latitude etc.
axes = list(map(guess_axis, coords))
axis = 'Z'
if axis in axes:
for coord in cube.coords(dim_coords=False):
if max(coord.shape) > 1 and \
iris.util.guess_coord_axis(coord) == axis:
coords[axes.index(axis)] = coord
# Re-order the coordinates to achieve the preferred
# horizontal/vertical associations.
def sort_key(coord):
order = {'X': 2, 'T': 1, 'Y': -1, 'Z': -2}
axis = guess_axis(coord)
return (order.get(axis, 0), coord and coord.name())
sorted_coords = sorted(coords, key=sort_key)
transpose = (sorted_coords != coords)
return PlotDefn(sorted_coords, transpose)
def replace_with_ternary_axis(ax):
"""
Replace a specified axis with a ternary equivalent.
Parameters
------------
ax : :class:`~matplotlib.axes.Axes`
Returns
------------
tax : :class:`~mpltern.ternary.TernaryAxes`
"""
fig = ax.figure
axes = get_ordered_axes(fig)
idx = axes.index(ax)
tax = fig.add_subplot(*get_axes_index(ax), projection="ternary")
fig.add_axes(tax) # make sure the axis is added to fig.children
fig.delaxes(ax) # remove the original axes
# update figure ordered axes
fig.orderedaxes = [a if ix != idx else tax for (ix, a) in enumerate(axes)]
return tax