Creating Random Points inside a created polygon which has no definite boundaries
5 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Ian Bouchard
am 28 Nov. 2017
Kommentiert: Walter Roberson
am 29 Nov. 2017
Hello I am currently working on a bit of a project where I need to be able to create random points inside of an already created polygon that does not have known set boundaries. For my code provided below I am using the state of Washington that does not have any set boundaries for me to generate my points from. If I could get some proper guidance on the steps to take that would be wonderful. Thank you!
states = shaperead('usastatehi.shp');
wa = p(45); %creates a polgon in the shape of Washington State
numPointsIn = 20;
for i = 1:numPointsIn
flagIsIn = 0;
while ~flagIsIn
x(i) = rand(1);
y(i) = rand(1);
flagIsIn = polyshape(wa);
end
end
plot(wa,'r+')
0 Kommentare
Akzeptierte Antwort
Walter Roberson
am 29 Nov. 2017
Caution: the below code probably has problems for areas that cross 180E/W:
states = shaperead('usastatehi.shp');
st = states(45); %creates a polgon in the shape of Washington State
stBB = st.BoundingBox;
st_minlat = min(stBB(:,2));
st_maxlat = max(stBB(:,2));
st_latspan = st_maxlat - st_minlat;
st_minlong = min(stBB(:,1));
st_maxlong = max(stBB(:,1));
st_longspan = st_maxlong - st_minlong;
stX = st.X;
stY = st.Y;
numPointsIn = 20;
for i = 1:numPointsIn
flagIsIn = 0;
while ~flagIsIn
x(i) = st_minlong + rand(1) * st_longspan;
y(i) = st_minlat + rand(1) * st_latspan;
flagIsIn = inpolygon(x(i), y(i), stX, stY);
end
end
mapshow(st, 'edgecolor', 'r', 'facecolor', 'none')
hold on
scatter(x, y, '.')
hold off
2 Kommentare
Walter Roberson
am 29 Nov. 2017
I think it is just left-over on your axes. mapshow() happens to construct the patch object in a way that does not clear the axes. You can add in a cla() before the mapshow()
Weitere Antworten (0)
Siehe auch
Kategorien
Mehr zu Computational Geometry finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!