geocontour.contourutil module

Utility functions for operations involving contours and contour searches

geocontour.contourutil.findstart(mask, searchdir='ru')

Find starting cell for contour, given a mask and a search criteria

Parameters:

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

  • searchdir ({'dr', 'ul', 'ru', 'ld', 'dl', 'ur', 'rd', 'lu'}) –

    2 char string describing the search directions [e.g. ‘dr’ will search rows moving downward and columns moving rightward, in that order]

    for a desired clockwise search:

    {‘dr’, ‘ul’, ‘ru’, ‘ld’}

    for a desired counterclockwise search:

    {‘dl’, ‘ur’, ‘rd’, ‘lu’}

Returns:

  • startcell (ndarray) – 1x2 array containing the indices of the start cell

  • startorientation (ndarray) – 1x2 array describing the orientation (entry direction) of the start cell

See also

parsestart

geocontour.contourutil.parsestart(start, buffermask)

Check start input for contour tracing

Mainly used internally for contour trace functions

Parameters:

  • start (array_like) –

    2x2 array describing the start cell and orientation

    row 1: indices of the start cell

    e.g. for start cell [2,3] second row (lat) and third column (lon)

    row 2: the start orientation

    e.g. orientation [0,1] points right, [1,0] points down

  • buffermask (ndarray) – 2D M+1xN+1 bool array where M=len(latitudes) and N=len(longitudes)

Returns:

  • startcell (ndarray) – 1x2 array containing the indices of the start cell

  • startorientation (ndarray) – 1x2 array describing the orientation (entry direction) of the start cell

See also

findstart

geocontour.contourutil.setstop(stop, startvisits, startcell, startorientation)

Create a stopping function for use in contour tracing while loop

Mainly used internally for contour trace functions

Parameters:

  • stop ({'Elisoff', 'Nvisits', 'either'}, default='either') –

    selector for the stopping criterion

    Elisoff

    stops when the start cell has been re-visited with the same orientation as started with

    Nvisits

    stops when the start cell has been re-visited N number of times (N set by startvisits parameter)

    either

    stops when either Elisoff or Nvisits has been satisfied

  • startvisits (int, default=3) – the number of times re-visiting the start cell will trigger an end to the search

  • startcell (ndarray) – 1x2 array containing the indices of the start cell

  • startorientation (ndarray) – 1x2 array describing the orientation (entry direction) of the start cell

Returns:

checkbreak – stopping function that takes a cell, orientation, and start visit counter as input

Return type:

function

See also

parsestart

Notes

startvisits parameter will only be utilized when stop parameter is set to ‘Nvisits’ or ‘either’

geocontour.contourutil.clean(contourcells, searchcells, latitudes=None, longitudes=None, closecontour=True, remcontourrepeat=True, remsearchrepeat=False)

Returns a cleaned contour that will pass checks

Mainly used internally for contour trace functions

Parameters:

  • contourcells (array_like) – list of 1x2 numpy arrays containing contour indices

  • searchcells (array_like) – list of 1x2 numpy arrays containing contour search indices

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

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

  • remcontourrepeat (bool, default=True) – select whether to remove consecutive repeating cells in the output contour

  • remsearchrepeat (bool, default=False) – select whether to remove consecutive repeating cells in the output contoursearch

  • closecontour (bool, default=True) – select whether to close the output contour (first cell = last cell)

Returns:

  • contour (ndarray) – 2D Nx2 array of ordered latitude/longitude points (degrees) describing the edge of a mask

  • contoursearch (ndarray) – 2D Nx2 array of ordered latitude/longitude points (degrees) describing the cells searched during contour tracing

Notes

If latitudes/longitudes not provided, returned contour/contoursearch will be indices of the input mask

geocontour.contourutil.fancysearch(contoursearch, contraction=0.2, shift=0.25)

Create a contour search that is visually more easy to follow via:

  • contraction, which ranges from 0 (no change) to 0.5 (completely flattened to contour cell edges)

  • shift, which ranges from 0 (no change) to 0.5 (half a grid cell)

Parameters:

  • contoursearch (ndarray) – 2D Nx2 array of ordered latitude/longitude points (degrees) describing the cells searched during contour tracing

  • contraction (float, default=0.2) – value determining how much contoursearch “shrinks” towards contour cell edges

  • shift (float, default=0.25) – value determining how much contoursearch “shifts” to avoid doubling back on itself

Returns:

fancycontoursearch – 2D Nx2 array of ordered latitude/longitude points describing the cells searched during contour tracing, with contraction and shift applied

Return type:

ndarray

See also

geocontour.output.plot