geocontour.maskutil module

Utility functions for operations involving masks and mask searches

geocontour.maskutil.bbox(latitudes, longitudes, boundary)

Check input dimensions (lat/lon) against input boundary and return min/max indicies of bounding box

Mainly used internally for mask search functions

Parameters:

• latitudes (ndarray) – 1D Nx1 array of latitude points (degrees)

• longitudes (ndarray) – 1D Nx1 array of longitude points (degrees)

• boundary (ndarray) – 2D Nx2 array of latitude/longitude points (degrees) with the last point equal to the first

Returns:

• boxlatmin (int) – the minimum bounding box latitude index

• boxlatmax (int) – the maximum bounding box latitude index

• boxlonmin (int) – the minimum bounding box longitude index

• boxlonmax (int) – the maximum bounding box longitude index

geocontour.maskutil.edge(mask, latitudes=None, longitudes=None, connectivity=8)

Find a mask’s edge cells only, and optionally an array of the edge cells

Parameters:

• mask (ndarray) – 2D MxN bool array where M=len(latitudes) and N=len(longitudes)

• latitudes (ndarray, optional) – 1D Nx1 array of latitude points (degrees)

• longitudes (ndarray, optional) – 1D Nx1 array of longitude points (degrees)

• connectivity ({4, 8}, default=8) –

  connectivity parameter for finding edge cells

  4

  test only lateral neighbors

  8

  test lateral and diagonal neighbors

Returns:

• edgemask (ndarray) – 2D bool array of the same dimensions as mask input

• edgecells (ndarray, optional) – 2D Nx2 bool array of latitude/longitude points (degrees) of edge cells (unordered), where N is number of edge cells

See also

vertex, conn

Notes

edgecells only returned if optional parameters latitudes and longitudes are provided

geocontour.maskutil.vertex(mask, latitudes, longitudes)

Find the vertex points of all cells in a mask, and the vertex points of only the mask edge

Parameters:

• mask (ndarray) – 2D MxN bool array where M=len(latitudes) and N=len(longitudes)

• latitudes (ndarray, optional) – 1D Nx1 array of latitude points (degrees)

• longitudes (ndarray, optional) – 1D Nx1 array of longitude points (degrees)

Returns:

• vertexpoints (ndarray) – 2D Nx2 array of latitude/longitude points (degrees) of all vertices of mask cells

• edgevertexpoints (ndarray) – 2D Nx2 array of latitude/longitude points (degrees) of all vertices of cells at the mask edge (8-connected)

See also

edge, conn

geocontour.maskutil.neighbors(cell, connectivity=8, direction='cw')

Find the neighbors of a cell, with selected connectivity and direction

Parameters:

• cell (ndarray) – 1x2 numpy array describing the indices of the cell

• connectivity ({4, 8}, default=8) –

  connectivity parameter for finding neighbor cells

  4

  test only lateral neighbors

  8

  test lateral and diagonal neighbors

• direction ({'cw', 'ccw'}, default='cw') – select the direction of the returned neighbors

Returns:

neighbors – 8x2 or 4x2 array of the neighboring cell indices for the input cell

Return type:

ndarray

See also

conn

geocontour.maskutil.conn(mask, checkcells='full', connectivity=8)

Determine whether a mask or its inverse are connected

Parameters:

• mask (ndarray) – 2D MxN bool array where M=len(latitudes) and N=len(longitudes)

• checkcells ({'full', 'empty'}, default='full') – select the mask cells to test (‘empty’ would select the mask inverse)

• connectivity ({4, 8}, default=8) –

  connectivity parameter for testing connectivity

  4

  test only lateral neighbors

  8

  test lateral and diagonal neighbors

Returns:

connected – descriptor for whether the input mask is connected under the input conditions

Return type:

bool