当我在 sklearn 中使用 knn 算法时,我可以获得我指定的半径内的最近邻居,即它返回该半径内最近邻居的圆形 . 是否有一个实现,您可以指定两个半径值以返回最近邻居的椭圆形状?
sklearn
knn
您可以在NearestNeighbors中指定自定义距离指标:
# aspect of the axis a, b of the ellipse aspect = b / a dist = lambda p0, p1: math.sqrt((p1[0] - p0[0]) * (p1[0] - p0[0]) + (p1[1] - p0[1]) * (p1[1] - p0[1]) * aspect) nn = NearestNeighbors(radius=1.0, metric=dist)
或直接use the KDTree与custom metric:
from sklearn.neighbors import KDTree import numpy as np X = np.array([[-1, -1], [-2, -1], [-3, -2], [1, 1], [2, 1], [3, 2]]) # aspect of the axis a, b of the ellipse aspect = b / a dist = DistanceMetric.get_metric('pyfunc', func = lambda p0, p1: math.sqrt((p1[0] - p0[0]) * (p1[0] - p0[0]) + (p1[1] - p0[1]) * (p1[1] - p0[1]) * aspect)) kdt = KDTree(X, leaf_size=30, metric=dist) # now kdt allows queries with ellipses with aspect := b / a kdt.query([0.1337, -0.42], k=6)
当然,您可以选择在距离度量中应用任何仿射变换,以获得定向椭圆的旋转和缩放 .
1 回答
您可以在NearestNeighbors中指定自定义距离指标:
或直接use the KDTree与custom metric:
当然,您可以选择在距离度量中应用任何仿射变换,以获得定向椭圆的旋转和缩放 .