Ramer-Douglas-Peucker line simplification: Difference between revisions
Ramer-Douglas-Peucker line simplification (view source)
Revision as of 15:07, 18 November 2023
, 6 months agoAdded XPL0 example.
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(Added XPL0 example.) |
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<pre>
[(0, 0), (2, -0.1), (3, 5), (7, 9), (9, 9)]
</pre>
=={{header|XPL0}}==
{{trans|C}}
<syntaxhighlight lang "XPL0">include xpllib; \for PerpDist and Print
func RDP(Points, Size, Epsilon, RemPoints);
\Reduce array Points using Ramer-Douglas-Peucker algorithm
\Return array of remaining points in RemPoints and its size
real Points; int Size; real Epsilon, RemPoints;
real Dist, DistMax;
int Index, I, Size1, Size2;
[\Find Index of point farthest from line between first and last points
DistMax:= 0.; Index:= 0;
for I:= 1 to Size-2 do
[Dist:= PerpDist(Points(I), Points(0), Points(Size-1));
if Dist > DistMax then
[DistMax:= Dist;
Index:= I;
];
];
if DistMax <= Epsilon then \replace in-between points with first and last points
[RemPoints(0):= Points(0);
RemPoints(1):= Points(Size-1);
return 2;
]
else \recursively check sub-line-segments
[Size1:= RDP(Points, Index+1, Epsilon, RemPoints);
RemPoints:= @RemPoints(Size1-1); \add retained points to array
Size2:= RDP(@Points(Index), Size-Index, Epsilon, RemPoints);
return Size1 + Size2 - 1; \for point at Index
];
];
real Points, RemPoints;
int Size, I;
[Points:= [ [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] ];
Size:= 10;
RemPoints:= RlRes(Size);
Size:= RDP(Points, Size, 1.0, RemPoints);
for I:= 0 to Size-1 do
[if I > 0 then Print(", ");
Print("[%1.1g, %1.1g]", RemPoints(I,0), RemPoints(I,1));
];
CrLf(0);
]</syntaxhighlight>
{{out}}
<pre>
[0, 0], [2, -0.1], [3, 5], [7, 9], [9, 9]
</pre>
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