epygram.geometries.ProjectedGeometry — Projected Geometry class

Contains the classes for 3D geometries of fields.

class epygram.geometries.ProjectedGeometry.ProjectedGeometry(name, grid, dimensions, vcoordinate, projection, position_on_horizontal_grid='__unknown__', geoid=None)[source]

Bases: epygram.geometries.AbstractGeometry.RectangularGridGeometry

Handles the geometry for a Projected 3-Dimensions Field.

Parameters

  • name –

    Name of geometrical type of representation of points on the Globe. Name must be among [‘lambert’, ‘mercator’, ‘polar_stereographic’,

    ’space_view’]

  • grid – Handles description of the horizontal grid.

  • dimensions – Handles grid dimensions.

  • vcoordinate – Handles vertical geometry parameters.

  • position_on_horizontal_grid –

    Position of points w/r to the horizontal. among: [‘upper-right’, ‘upper-left’,

    ’lower-left’, ‘lower-right’, ‘center-left’, ‘center-right’, ‘lower-center’, ‘upper-center’, ‘center’, ‘__unknown__’]

  • geoid – To specify geoid shape.

compass_grid(subzone=None, position=None)[source]

Get the compass grid, i.e. the angle between Y-axis and North for each gridpoint.

Parameters

  • subzone –

    optional, among (‘C’, ‘CI’), for LAM grids only, returns the grid resp. for the C or C+I zone off the C+I+E zone.

    Default is no subzone, i.e. the whole field.

  • position – position of lonlat grid with respect to the model cell. Defaults to self.position_on_horizontal_grid.

default_cartopy_CRS()

Note

Requires plugin: with_cartopy (config.activate_plugins)

Create a cartopy.crs appropriate to the Geometry.

distance(end1, end2)[source]

Computes the distance between two points along a straight line in the geometry.

Parameters

  • end1 – must be a tuple (lon, lat) in degrees.

  • end2 – must be a tuple (lon, lat) in degrees.

get_cartopy_extent(subzone=None)

Note

Requires plugin: with_cartopy (config.activate_plugins)

Gets the extension of the geometry in the default crs :param subzone: defines the LAM subzone to be included, in LAM case,

among: ‘C’, ‘CI’.

Returns

(xmin, xmax, ymin, ymax) as expected by matplotlib’s ax.set_extent

getcenter()[source]

Returns the coordinate of the grid center as a tuple of Angles (center_lon, center_lat).

ij2ll(i, j, position=None)[source]

Return the (lon, lat) coordinates of point (i,j), in degrees.

Parameters

  • i – X index of point in the 2D matrix of gridpoints

  • j – Y index of point in the 2D matrix of gridpoints

  • position – lat lon position to return with respect to the model cell. Defaults to self.position_on_horizontal_grid.

ij2xy(i, j, position=None)[source]

Return the (x, y) coordinates of point (i,j), in the projection.

Parameters

  • i – X index of point in the 2D matrix of gridpoints

  • j – Y index of point in the 2D matrix of gridpoints

  • position – position to return with respect to the model cell. Defaults to self.position_on_horizontal_grid.

Note that origin of coordinates in projection is the center of the C+I domain.

linspace(end1, end2, num)[source]

Returns evenly spaced points over the specified interval. Points are lined up in the geometry.

Parameters

  • end1 – must be a tuple (lon, lat) in degrees.

  • end2 – must be a tuple (lon, lat) in degrees.

  • num – number of points, including point1 and point2.

ll2ij(lon, lat, position=None)[source]

Return the (i, j) indexes of point (lon, lat) in degrees, in the 2D matrix of gridpoints.

Parameters

  • lon – longitude of point in degrees

  • lat – latitude of point in degrees

  • position – lat lon position to return with respect to the model cell. Defaults to self.position_on_horizontal_grid.

Caution: (i,j) are float.

ll2xy(lon, lat)[source]

Return the (x, y) coordinates of point (lon, lat) in degrees.

Parameters

  • lon – longitude of point in degrees

  • lat – latitude of point in degrees

Note that origin of coordinates in projection is the center of the C+I domain.

make_section_geometry(end1, end2, points_number=None, resolution=None, position=None)[source]

Returns a projected Geometry.

Parameters

  • end1 – must be a tuple (lon, lat) in degrees.

  • end2 – must be a tuple (lon, lat) in degrees.

  • points_number – defines the total number of horizontal points of the section (including ends). If None, defaults to a number computed from the ends and the resolution.

  • resolution – defines the horizontal resolution to be given to the field. If None, defaults to the horizontal resolution of the field.

  • position – defines the position of data in the grid (defaults to ‘center’)

map_factor(lat)[source]

Returns the map factor at the given latitude(s) lat in degrees.

map_factor_field(position=None)[source]

Returns a new field whose data is the map factor over the field.

Parameters

position – grid position with respect to the model cell. Defaults to self.position_on_horizontal_grid.

mesh_area(lat)[source]

Compute the area of a mesh/gridpoint, given its latitude.

mesh_area_field(position=None)[source]

Returns a new field whose data is the mesh area of gridpoints, i.e. X_resolution x Y_resolution / m^2, where m is the local map factor.

Parameters

position – grid position with respect to the model cell. Defaults to self.position_on_horizontal_grid.

plane_azimuth(end1, end2)[source]

Initial bearing from end1 to end2 points in plane local referential geometry.

Parameters

  • end1 – must be a tuple (lon, lat) in degrees.

  • end2 – must be a tuple (lon, lat) in degrees.

reproject_wind_on_lonlat(u, v, lon=None, lat=None, map_factor_correction=True, reverse=False)[source]

Reprojects a wind vector (u, v) on the grid onto real axes, i.e. with components on true zonal/meridian axes.

Parameters

  • u – the u == zonal-on-the-grid component of wind

  • v – the v == meridian-on-the-grid component of wind

  • lon – longitudes of points in degrees, if u/v are not vectors on the whole grid

  • lat – latitudes of points in degrees, if u/v are not vectors on the whole grid

:param map_factor_correction:, applies a correction of magnitude due

to map factor.

Parameters

reverse – if True, apply the reverse reprojection.

resolution_ij(i, j)[source]

Returns the distance to the nearest point of (i,j) point.

Parameters

  • i – X index of point in the 2D matrix of gridpoints

  • j – Y index of point in the 2D matrix of gridpoints

resolution_ll(lon, lat)[source]

Returns the local resolution at the nearest point of lon/lat. It’s the distance between this point and its closest neighbour.

Parameters

  • lon – longitude of the point in degrees

  • lat – latitude of the point in degrees

property secant_projection

Is the projection secant to the sphere ? (or tangent)

select_subzone(subzone)[source]

If a LAMzone defines the geometry, select only the subzone from it and return a new geometry object.

Parameters

subzone – among (‘C’, ‘CI’).

tolerant_equal(other, tolerance=2.220446049250313e-16)[source]

Test of equality by recursion on the object’s attributes, with a tolerance.

xy2ij(x, y, position=None)[source]

Return the (i, j) indexes of point (x, y), in the 2D matrix of gridpoints.

Parameters

  • x – X coordinate of point in the projection

  • y – Y coordinate of point in the projection

  • position – position to return with respect to the model cell. Defaults to self.position_on_horizontal_grid.

Caution: (i,j) are float (the nearest grid point is the nearest integer).

Note that origin of coordinates in projection is the center of the C+I domain.

xy2ll(x, y)[source]

Return the (lon, lat) coordinates of point (x, y) in the 2D matrix of gridpoints*(i,j)*, in degrees.

Parameters

  • x – X coordinate of point in the projection

  • y – Y coordinate of point in the projection

Note that origin of coordinates in projection is the center of the C+I domain.