function [x,y] = choose2dPoints(N,a)
% Use:   [x,y] = choose2dPoints(N,a)
% Displays a plot in which the user can interactively select N data points in
% 2-D where the boundary of the selection of data points is specified by the 
% axis variable a
% Returns the x coordinates and y coordinates which can be saved in a
% .mat file for later use by issuing the command save fileName x y.
% Author: Grady Wright

% Create the figure with the appropriate axis.
figure, axis(a), hold on;

% Instructions
str = sprintf('Using the mouse, select the location of the data points\n you wish to include in your distribution. You must press \n enter after selecting each point. A counter will be printed \n to the console indicating what number of the data point you are\n currently selecting.');
str
counter = 0;
while (counter < N)
   try, [newx,newy] = ginput; x(counter+1) = newx(1); y(counter+1) = newy(1);...
   counter = counter+1, catch, 'Error - Select point then press enter', end;
   plot(x,y,'or');
end
hold off;

x = x';
y = y';