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Zhang-Suen thinning algorithm: Difference between revisions
Added groovy version
(→{{header|J}}: separate out explicit version) |
(Added groovy version) |
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Line 301:
To thinned:
...........................................................
...........................................................
....#.##########.......................#######.............
.....##........#...................####.......#............
.....#..........#.................##.......................
.....#..........#................#.........................
.....#..........#................#.........................
.....#..........#................#.........................
.....############...............#..........................
.....#..........#...............#..........................
.....#..........#................#.........................
.....#..........#................#.........................
.....#..........#................#.........................
.....#............................##.......................
.....#.............................############............
.......................###..........................###....
...........................................................
...........................................................</pre>
=={{header|Groovy}}==
<lang groovy>def zhangSuen(text) {
def image = text.split('\n').collect { line -> line.collect { it == '#' ? 1 : 0} }
def p2, p3, p4, p5, p6, p7, p8, p9
def step1 = { (p2 * p4 * p6 == 0) && (p4 * p6 * p8 == 0) }
def step2 = { (p2 * p4 * p8 == 0) && (p2 * p6 * p8 == 0) }
def reduce = { step ->
def toWhite = []
image.eachWithIndex{ line, y ->
line.eachWithIndex{ pixel, x ->
if (!pixel) return
(p2, p3, p4, p5, p6, p7, p8, p9) = [image[y-1][x], image[y-1][x+1], image[y][x+1], image[y+1][x+1], image[y+1][x], image[y+1][x-1], image[y][x-1], image[y-1][x-1]]
def a = [[p2,p3],[p3,p4],[p4,p5],[p5,p6],[p6,p7],[p7,p8],[p8,p9],[p9,p2]].collect { a1, a2 -> (a1 == 0 && a2 ==1) ? 1 : 0 }.sum()
def b = [p2, p3, p4, p5, p6, p7, p8, p9].sum()
if (a != 1 || b < 2 || b > 6) return
if (step.call()) toWhite << [y,x]
}
}
toWhite.each { y, x -> image[y][x] = 0 }
!toWhite.isEmpty()
}
while (reduce(step1) | reduce(step2));
image.collect { line -> line.collect { it ? '#' : '.' }.join('') }.join('\n')
}</lang>
Testing:
<lang groovy>def small = """\
................................
.#########.......########.......
.###...####.....####..####......
.###....###.....###....###......
.###...####.....###.............
.#########......###.............
.###.####.......###....###......
.###..####..###.####..####.###..
.###...####.###..########..###..
................................""".stripIndent()
def large = """\
...........................................................
.#################...................#############.........
.##################...............################.........
.###################............##################.........
.########.....#######..........###################.........
...######.....#######.........#######.......######.........
...######.....#######........#######.......................
...#################.........#######.......................
...################..........#######.......................
...#################.........#######.......................
...######.....#######........#######.......................
...######.....#######........#######.......................
...######.....#######.........#######.......######.........
.########.....#######..........###################.........
.########.....#######.######....##################.######..
.########.....#######.######......################.######..
.########.....#######.######.........#############.######..
...........................................................""".stripIndent()
[small, large].each {
println "From:"
println it
println "To:"
println zhangSuen(it)
println()
}</lang>
Output:
<pre>From:
................................
.#########.......########.......
.###...####.....####..####......
.###....###.....###....###......
.###...####.....###.............
.#########......###.............
.###.####.......###....###......
.###..####..###.####..####.###..
.###...####.###..########..###..
................................
To:
................................
..#######.........######........
..#.....#........##.............
..#......#.......#..............
..#.....#........#..............
..#####.#........#..............
.......##........#..............
........#....#...##....##...#...
.........#.........####.........
................................
From:
...........................................................
.#################...................#############.........
.##################...............################.........
.###################............##################.........
.########.....#######..........###################.........
...######.....#######.........#######.......######.........
...######.....#######........#######.......................
...#################.........#######.......................
...################..........#######.......................
...#################.........#######.......................
...######.....#######........#######.......................
...######.....#######........#######.......................
...######.....#######.........#######.......######.........
.########.....#######..........###################.........
.########.....#######.######....##################.######..
.########.....#######.######......################.######..
.########.....#######.######.........#############.######..
...........................................................
To:
...........................................................
...........................................................
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