Merge pull request #1840 from Shaikh-Ubaid/pkg_convexhull

PKG: Add convexhull computation package

Author: Shaikh-Ubaid

integration_tests/CMakeLists.txt

@@ -529,6 +529,7 @@ RUN(NAME test_package_01     LABELS cpython llvm)
 RUN(NAME test_pkg_lpdraw     LABELS cpython llvm wasm)
 RUN(NAME test_pkg_lnn_01        LABELS cpython llvm)
 RUN(NAME test_pkg_lnn_02        LABELS cpython llvm)
+RUN(NAME test_pkg_lpconvexhull  LABELS cpython c)
 
 RUN(NAME generics_01         LABELS cpython llvm c)
 RUN(NAME generics_02         LABELS cpython llvm c)

integration_tests/lpconvexhull/__init__.py

@@ -0,0 +1 @@
+from .lpconvexhull_main import convex_hull

integration_tests/lpconvexhull/lpconvexhull_main.py

@@ -0,0 +1,56 @@
+from lpython import i32
+from .utils import min, distance
+
+def orientation(p: tuple[i32, i32], q: tuple[i32, i32], r: tuple[i32, i32]) -> i32:
+    # Function to find the orientation of triplet (p, q, r)
+    # Returns the following values:
+    # 0: Colinear
+    # 1: Clockwise
+    # 2: Counterclockwise
+    value: i32 = (q[1] - p[1]) * (r[0] - q[0]) - (q[0] - p[0]) * (r[1] - q[1])
+    if value == 0:
+        return 0  # Colinear
+    elif value > 0:
+        return 1  # Clockwise
+    else:
+        return 2  # Counterclockwise
+
+
+def convex_hull(points: list[tuple[i32, i32]]) -> list[tuple[i32, i32]]:
+    """Finds the convex hull of a set of points.
+
+    Args:
+        points: A list of points.
+
+    Returns:
+        A list of points that form the convex hull.
+    """
+
+    n: i32 = len(points)
+    if n < 3:
+        return [(-1, -1)]  # Convex hull not possible
+
+    # Find the leftmost point
+    leftmost: tuple[i32, i32] = min(points)
+    hull: list[tuple[i32, i32]] = []
+
+    p: tuple[i32, i32] = leftmost
+
+    while True:
+        hull.append(p)
+        q: tuple[i32, i32] = points[0]
+
+        r: tuple[i32, i32]
+        for r in points:
+            if r == p or r == q:
+                continue
+            direction: i32 = orientation(p, q, r)
+            if direction == 1 or (direction == 0 and distance(p, r) > distance(p, q)):
+                q = r
+
+        p = q
+
+        if p == leftmost:
+            break
+
+    return hull

integration_tests/lpconvexhull/utils.py

@@ -0,0 +1,29 @@
+from lpython import i32, f64
+
+def min(points: list[tuple[i32, i32]]) -> tuple[i32, i32]:
+    """Finds the left-most point in a list of points.
+
+    Args:
+        points: A list of points.
+
+    Returns:
+        The left-most point in the list.
+    """
+
+    left_most_point: tuple[i32, i32] = points[0]
+    point: tuple[i32, i32]
+    for point in points:
+        if point[0] < left_most_point[0]:
+            left_most_point = point
+
+    return left_most_point
+
+
+def distance(p: tuple[i32, i32], q: tuple[i32, i32]) -> f64:
+    # Function to calculate the Euclidean distance between two points
+    x1: i32; y1: i32
+    x2: i32; y2: i32
+
+    x1, y1 = p
+    x2, y2 = q
+    return f64((x2 - x1) ** 2 + (y2 - y1) ** 2) ** 0.5

integration_tests/test_pkg_lpconvexhull.py

@@ -0,0 +1,32 @@
+from lpython import Const, i32, f64
+
+from lpdraw import Line, Circle, Clear, Display
+from lpconvexhull import convex_hull
+from numpy import empty, int32
+
+def plot_graph(polygon: list[tuple[i32, i32]], points: list[tuple[i32, i32]]):
+    Width: Const[i32] = 500 # x-axis limits [0, 499]
+    Height: Const[i32] = 500 # y-axis limits [0, 499]
+    Screen: i32[Height, Width] = empty((Height, Width), dtype=int32)
+    Clear(Height, Width, Screen)
+
+    i: i32
+    n: i32 = len(polygon)
+    for i in range(n):
+        Line(Height, Width, Screen, polygon[i][0], polygon[i][1], polygon[(i + 1) % n][0], polygon[(i + 1) % n][1])
+
+    point_size: i32 = 5
+    for i in range(len(points)):
+        Circle(Height, Width, Screen, points[i][0], points[i][1], f64(point_size))
+
+    Display(Height, Width, Screen)
+
+def main0():
+    points: list[tuple[i32, i32]] = [(445, 193), (138, 28), (418, 279), (62, 438), (168, 345), (435, 325), (293, 440), (158, 94), (403, 288), (136, 278), (141, 243), (287, 313), (338, 492), (172, 78), (29, 404), (79, 377), (184, 91), (69, 324), (408, 72), (494, 1)]
+    convex_hull_points: list[tuple[i32, i32]] = convex_hull(points)
+    # print(convex_hull_points)
+    plot_graph(convex_hull_points, points)
+
+    assert convex_hull_points == [(29, 404), (138, 28), (494, 1), (435, 325), (338, 492), (62, 438)]
+
+main0()