Add new function to find surrounding nodes for a given node. This was ported...

Add new function to find surrounding nodes for a given node. This was ported from the Python FVCOM toolbox (PyFVCOM).

utilities/surrounders.m

+function nodes = surrounders(n, triangles)
+% Return the IDs of the nodes surrounding node number `n'.
+%
+% INPUTS:
+%   n
+%       Node ID around which to find the connected nodes.
+%   triangles
+%       Triangulation matrix to find the connected nodes.
+%
+% OUTPUTS:
+%   surroundingidx
+%       Indices of the surrounding nodes.
+%
+% Author(s):
+%   Pierre Cazenave (Plymouth Marine Laboratory)
+%
+% Revision history:
+%   2015-02-19 First version based on the PyFVCOM.grid_tools surrounders
+%   function.
+%
+% Notes:
+%
+% Check it works with:
+% [x, y] = meshgrid(1:25, 100:125);
+% x = x(:) + randn(numel(x), 1) * 0.1;
+% y = y(:) + randn(numel(y), 1) * 0.1;
+% tri = delaunay([x, y]);
+% for n = linspace(1, length(x) - 1, 5)
+% 	  aa = surrounders(n, tri)
+% 	  figure
+% 	  triplot(x, y, tri)
+% 	  plot(x(n), y(n), 'ro')
+% 	  plot(x(aa), y(aa), 'ko')
+% 	  xlim(min(x(aa)) - 1, max(x(aa)) + 1)
+% 	  ylim(min(y(aa)) - 1, max(y(aa)) + 1)
+% 	  legend
+% end
+
+eidx = max((abs(triangles - n) == 0), [], 2);
+nodes = unique(triangles(triangles(eidx) ~= n, :));