hasufell/cga
1
1
Fork 0
Code Issues Pull Requests Releases Wiki Activity

ALGO: Improve readability by introducing notcw

Browse Source
This commit is contained in:
hasufell
2014-10-12 20:37:24 +02:00
parent be2787103a
commit f82c948055
3 changed files with 44 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
Algorithms/ConvexHull/GrahamScan.hs
View File

@@ -25,14 +25,14 @@ return (scanHalf upperHull restu) ++
=== begin scanHalf function ===
scanHalf (min 3 elem => lowerHull) (min 1 elem => rest)
| isCounterClockWise (last3Elements lowerHull) == True
| isNotClockWise (last3Elements lowerHull) == True
= scanHalf (lowerHull + head rest) (tail rest)
| otherwise
= scanHalf (deleteSndToLastElem lowerHull + head rest)
(rest)
scanHalf (min 3 elem => lowerHull ) []
| isCounterClockWise (last3Elements lowerHull) == True
| isNotClockWise (last3Elements lowerHull) == True
= return lowerHull
| otherwise
= scanHalf (deleteSndToLastElem lowerHull) []
@@ -49,26 +49,26 @@ scanHalf lowerHull _ = lowerHull
xs = [(100, 100), (200, 450), (250, 250)]
ys = [(300, 400), (400, 200)]
ccw (100, 100) (200, 450) (250, 250) => false, pop snd2last of xs
notcw (100, 100) (200, 450) (250, 250) => false, pop snd2last of xs
===
move first of ys to end of xs
xs = [(100, 100), (250, 250), (300, 400)]
ys = [(400, 200)]
ccw (100, 100), (250, 250) (300, 400) => true
notcw (100, 100), (250, 250) (300, 400) => true
===
move first of ys to end of xs
xs = [(100, 100), (250, 250), (300, 400), (400, 200)]
ys = []
ccw (250, 250) (300, 400) (400, 200) => false, pop snd2last of xs
notcw (250, 250) (300, 400) (400, 200) => false, pop snd2last of xs
===
xs = [(100, 100), (250, 250), (400, 200)]
ys = []
ccw (100, 100) (250, 250) (400, 200) => false, pop snd2last of xs
notcw (100, 100) (250, 250) (400, 200) => false, pop snd2last of xs
===
xs = [(100, 100), (400, 200)]
ys = []
@@ -91,13 +91,13 @@ grahamGetCH vs =
-> [PT] -- ^ the rest of the points
-> [PT] -- ^ all convex hull points for the half
scanH hs@(x:y:z:xs) (r':rs')
| ccw z y x = scanH (r':hs) rs'
| otherwise = scanH (x:z:xs) (r':rs')
| notcw z y x = scanH (r':hs) rs'
| otherwise = scanH (x:z:xs) (r':rs')
scanH hs@(x:y:z:xs) []
| ccw z y x = hs
| otherwise = scanH (x:z:xs) []
scanH hs (r':rs') = scanH (r':hs) rs'
scanH hs _ = hs
| notcw z y x = hs
| otherwise = scanH (x:z:xs) []
scanH hs (r':rs') = scanH (r':hs) rs'
scanH hs _ = hs
-- |Compute all steps of the graham scan algorithm to allow
@@ -116,12 +116,12 @@ grahamGetCHSteps vs =
where
scanH c' hs@(x:y:z:xs) (r':rs')
| c' >= c = hs
| ccw z y x = scanH (c' + 1) (r':hs) rs'
| notcw z y x = scanH (c' + 1) (r':hs) rs'
| otherwise = scanH (c' + 1) (x:z:xs) (r':rs')
scanH _ [x,y] [] = [y,x]
scanH c' hs@(x:y:z:xs) []
| c' >= c = hs
| ccw z y x = hs
| notcw z y x = hs
| otherwise = scanH (c' + 1) (x:z:xs) []
scanH c' hs (r':rs')
| c' >= c = hs