Python-仅绘制数据集的最外层点
我有一组排列成方形的随机点(带有粗糙边缘),我只想绘制最外面的点——只绘制最靠近形状假想边缘的点(这样我就可以在多个有重叠的类似数据集之间有一个清晰的边界)Python-仅绘制数据集的最外层点,python,matplotlib,plot,Python,Matplotlib,Plot,我有一组排列成方形的随机点(带有粗糙边缘),我只想绘制最外面的点——只绘制最靠近形状假想边缘的点(这样我就可以在多个有重叠的类似数据集之间有一个清晰的边界) 非常感谢您对我如何选择这些要点的任何建议 您可以计算数据集的凸包。这里有一个;有几种可能具有更好的性能: import random import sys import matplotlib.pyplot as plt CLOCKWISE = -1 COLLINEAR = 0 COUNTERCLOCKWISE = +1 eps = sys
非常感谢您对我如何选择这些要点的任何建议 您可以计算数据集的凸包。这里有一个;有几种可能具有更好的性能:
import random
import sys
import matplotlib.pyplot as plt
CLOCKWISE = -1
COLLINEAR = 0
COUNTERCLOCKWISE = +1
eps = sys.float_info.epsilon
def orientation(a, b):
x0, y0 = a
x1, y1 = b
cross = x0 * y1 - x1 * y0
if cross > eps:
return COUNTERCLOCKWISE
elif cross < -eps:
return CLOCKWISE
else:
return COLLINEAR
def same_halfplane(a, b):
x0, y0 = a
x1, y1 = b
dot = x0 * x1 + y0 * y1
if dot >= eps:
return True
elif dot < eps:
return False
def jarvis(points):
"""
http://cgi.di.uoa.gr/~compgeom/pycgalvisual/whypython.shtml
Jarvis Convex Hull algorithm.
"""
points = points[:]
r0 = min(points)
hull = [r0]
r, u = r0, None
remainingPoints = [x for x in points if x not in hull]
while u != r0 and remainingPoints:
u = random.choice(remainingPoints)
for t in points:
a = (u[0] - r[0], u[1] - r[1])
b = (t[0] - u[0], t[1] - u[1])
if (t != u and
(orientation(a, b) == CLOCKWISE or
(orientation(a, b) == COLLINEAR and
same_halfplane(a, b)))):
u = t
r = u
points.remove(r)
hull.append(r)
try:
remainingPoints.remove(r)
except ValueError:
# ValueError: list.remove(x): x not in list
pass
return hull
if __name__ == '__main__':
points = iter(random.uniform(0, 10) for _ in xrange(20))
points = zip(points, points)
hull = jarvis(points)
px, py = zip(*points)
hx, hy = zip(*hull)
plt.plot(px, py, 'b.', markersize=10)
plt.plot(hx, hy, 'g.-', markersize=10)
plt.show()
随机导入
导入系统
将matplotlib.pyplot作为plt导入
顺时针=-1
共线=0
逆时针=+1
eps=sys.float\u info.epsilon
def方向(a、b):
x0,y0=a
x1,y1=b
交叉=x0*y1-x1*y0
如果交叉>每股收益:
逆时针返回
elif交叉<-eps:
顺时针返回
其他:
返回共线
def相同_半平面(a、b):
x0,y0=a
x1,y1=b
点=x0*x1+y0*y1
如果dot>=eps:
返回真值
elif dot
您可以使用scipy的凸包函数,请参阅。 文档页面给出了以下示例
from scipy.spatial import ConvexHull
points = np.random.rand(30, 2) # 30 random points in 2-D
hull = ConvexHull(points)
import matplotlib.pyplot as plt
plt.plot(points[:,0], points[:,1], 'o')
# plot convex hull polygon
plt.plot(points[hull.vertices,0], points[hull.vertices,1], 'r--', lw=2)
# plot convex full vertices
plt.plot(points[hull.vertices[0],0], points[hull.vertices[0],1], 'ro')
plt.show()
你能提供到目前为止你在am中得到的代码吗?我现在只是添加代码,但下面的答案解决了问题。谢谢