Ramer-Douglas-Peucker line simplification: Difference between revisions
Ramer-Douglas-Peucker line simplification (view source)
Revision as of 15:28, 29 January 2024
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</pre>
===Version 2===
{{trans|ooRexx}}
<syntaxhighlight lang="rexx">
/*REXX program uses the Ramer-Douglas-Peucker (RDP) line simplification algorithm for*/
Line 1,643:
Numeric Digits prec
r=r+0
Return r
</syntaxhighlight>
{{out|output|text= when using the default inputs:}}
<pre>
Line 1,797 ⟶ 1,798:
(9, 9)
</pre>
=={{header|Scala}}==
{{trans|Kotlin}}
<syntaxhighlight lang="scala">// version 1.1.0
object SimplifyPolyline extends App {
type Point = (Double, Double)
def perpendicularDistance(
pt: Point,
lineStart: Point,
lineEnd: Point
): Double = {
var dx = lineEnd._1 - lineStart._1
var dy = lineEnd._2 - lineStart._2
// Normalize
val mag = math.hypot(dx, dy)
if (mag > 0.0) { dx /= mag; dy /= mag }
val pvx = pt._1 - lineStart._1
val pvy = pt._2 - lineStart._2
// Get dot product (project pv onto normalized direction)
val pvdot = dx * pvx + dy * pvy
// Scale line direction vector and subtract it from pv
val ax = pvx - pvdot * dx
val ay = pvy - pvdot * dy
math.hypot(ax, ay)
}
def RamerDouglasPeucker(
pointList: List[Point],
epsilon: Double
): List[Point] = {
if (pointList.length < 2)
throw new IllegalArgumentException("Not enough points to simplify")
// Check if there are points to process
if (pointList.length > 2) {
// Find the point with the maximum distance from the line between the first and last
val (dmax, index) = pointList.zipWithIndex
.slice(1, pointList.length - 1)
.map { case (point, i) =>
(perpendicularDistance(point, pointList.head, pointList.last), i)
}
.maxBy(_._1)
// If max distance is greater than epsilon, recursively simplify
if (dmax > epsilon) {
val firstLine = pointList.take(index + 1)
val lastLine = pointList.drop(index)
val recResults1 = RamerDouglasPeucker(firstLine, epsilon)
val recResults2 = RamerDouglasPeucker(lastLine, epsilon)
// Combine the results
(recResults1.init ++ recResults2).distinct
} else {
// If no point is further than epsilon, return the endpoints
List(pointList.head, pointList.last)
}
} else {
// If there are only two points, just return them
pointList
}
}
val pointList = List(
(0.0, 0.0),
(1.0, 0.1),
(2.0, -0.1),
(3.0, 5.0),
(4.0, 6.0),
(5.0, 7.0),
(6.0, 8.1),
(7.0, 9.0),
(8.0, 9.0),
(9.0, 9.0)
)
val simplifiedPointList = RamerDouglasPeucker(pointList, 1.0)
println("Points remaining after simplification:")
simplifiedPointList.foreach(println)
}
</syntaxhighlight>
{{out}}
<pre>
Points remaining after simplification:
(0.0,0.0)
(2.0,-0.1)
(3.0,5.0)
(7.0,9.0)
(9.0,9.0)
</pre>
=={{header|Sidef}}==
Line 1,902 ⟶ 2,004:
{{trans|Go}}
{{libheader|Wren-dynamic}}
<syntaxhighlight lang="
var Point = Tuple.create("Point", ["x", "y"])
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