Ramer-Douglas-Peucker line simplification: Difference between revisions
Ramer-Douglas-Peucker line simplification (view source)
Revision as of 08:13, 15 January 2024
, 4 months agoadd ooRexx
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<pre>@[(x: 0.0, y: 0.0), (x: 2.0, y: -0.1), (x: 3.0, y: 5.0), (x: 7.0, y: 9.0), (x: 9.0, y: 9.0)]</pre>
={{header|ooRexx}}==
<syntaxhighlight lang="oorexx">
/*REXX program uses the Ramer-Douglas-Peucker (RDP) line simplification algorithm for*/
/*--------------------------- reducing the number of points used to define its shape. */
Parse Arg epsilon pl /*obtain optional arguments from the CL*/
If epsilon='' | epsilon=',' then epsilon= 1 /*Not specified? Then use the default.*/
If pl='' Then pl= '(0,0) (1,0.1) (2,-0.1) (3,5) (4,6) (5,7) (6,8.1) (7,9) (8,9) (9,9)'
Say ' error threshold:' epsilon
Say ' points specified:' pl
Say 'points simplified:' dlp(pl)
Exit
dlp: Procedure Expose epsilon
Parse Arg pl
plc=pl
Do i=1 By 1 While plc<>''
Parse Var plc '(' X ',' y ')' plc
p.i=.point~new(x,y)
End
end=i-1
dmax=0
index=0
Do i=2 To end-1
d=distpg(p.i,.line~new(p.1,p.end))
If d>dmax Then Do
index=i
dmax=d
End
End
If dmax>epsilon Then Do
rla=dlp(subword(pl,1,index))
rlb=dlp(subword(pl,index,end))
rl=subword(rla,1,words(rla)-1) rlb
End
Else
rl=word(pl,1) word(pl,end)
Return rl
::CLASS point public
::ATTRIBUTE X
::ATTRIBUTE Y
::METHOD init PUBLIC
Expose X Y
Use Arg X,Y
::CLASS line public
::ATTRIBUTE A
::ATTRIBUTE B
::METHOD init PUBLIC
Expose A B
Use Arg A,B
If A~x=B~x & A~y=B~y Then Do
Say 'not a line'
Return .nil
End
::METHOD k PUBLIC
Expose A B
ax=A~x; ay=A~y; bx=B~x; by=B~y
If ax=bx Then
res='infinite'
Else
res=(by-ay)/(bx-ax)
Return res
::METHOD d PUBLIC
Expose A B
ax=A~x; ay=A~y
If self~k='infinite' Then
res='indeterminate'
Else
res=round(ay-ax*self~k)
Return res
::ROUTINE distpg PUBLIC --Compute the distance from a point to a line
/***********************************************************************
* Compute the distance from a point to a line
***********************************************************************/
Use Arg A,g
ax=A~x; ay=A~y
k=g~k
If k='infinite' Then Do
Parse Value g~kxd With 'x='gx
res=gx-ax
End
Else
res=(ay-k*ax-g~d)/rxCalcsqrt(1+k**2)
Return abs(res)
::ROUTINE round PUBLIC --Round a number to 3 decimal digits
/***********************************************************************
* Round a nmber to 3 decimal digits
***********************************************************************/
Use Arg z,d
Numeric Digits 30
res=z+0
If d>'' Then
res=format(res,9,6)
Return strip(res)
::requires rxMath library
</syntaxhighlight>
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<pre> error threshold: 1
points specified: (0,0) (1,0.1) (2,-0.1) (3,5) (4,6) (5,7) (6,8.1) (7,9) (8,9) (9,9)
points simplified: (0,0) (2,-0.1) (3,5) (7,9) (9,9)</pre>
=={{header|Openscad}}==
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