Ramer-Douglas-Peucker line simplification: Difference between revisions
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[[0, 0], [2, -1/10], [3, 5], [7, 9], [9, 9]]
</pre>
=={{header|Yabasic}}==
<lang Yabasic>sub perpendicularDistance(tabla(), i, ini, fin)
local dx, cy, mag, pvx, pvy, pvdot, dsx, dsy, ax, ay
dx = tabla(fin, 1) - tabla(ini, 1)
dy = tabla(fin, 2) - tabla(ini, 2)
//Normalise
mag = (dx^2 + dy^2)^0.5
if mag > 0 dx = dx / mag : dy = dy / mag
pvx = tabla(i, 1) - tabla(ini, 1)
pvy = tabla(i, 2) - tabla(ini, 2)
//Get dot product (project pv onto normalized direction)
pvdot = dx * pvx + dy * pvy
//Scale line direction vector
dsx = pvdot * dx
dsy = pvdot * dy
//Subtract this from pv
ax = pvx - dsx
ay = pvy - dsy
return (ax^2 + ay^2)^0.5
end sub
sub DouglasPeucker(PointList(), ini, fin, epsilon)
local dmax, index, i, d
// Find the point with the maximum distance
for i = ini + 1 to fin
d = perpendicularDistance(PointList(), i, ini, fin)
if d > dmax index = i : dmax = d
next
// If max distance is greater than epsilon, recursively simplify
if dmax > epsilon then
PointList(index, 3) = true
// Recursive call
DouglasPeucker(PointList(), ini, index, epsilon)
DouglasPeucker(PointList(), index, fin, epsilon)
end if
end sub
data 0,0, 1,0.1, 2,-0.1, 3,5, 4,6, 5,7, 6,8.1, 7,9, 8,9, 9,9
dim matriz(10, 3)
for i = 1 to 10
read matriz(i, 1), matriz(i, 2)
next
DouglasPeucker(matriz(), 1, 10, 1)
matriz(1, 3) = true : matriz(10, 3) = true
for i = 1 to 10
if matriz(i, 3) print matriz(i, 1), matriz(i, 2)
next</lang>
=={{header|zkl}}==
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