如何删除Python轮廓中的0级线？

import numpy as np
import matplotlib.pyplot as plt

# 创建数据
x = np.linspace(-3, 3, 100)
y = np.linspace(-3, 3, 100)
X, Y = np.meshgrid(x, y)
Z = X**2 + Y**2

# 生成轮廓
fig, ax = plt.subplots()
# levels参数设置轮廓的级别，通过不包含0来删除0级线
levels = np.linspace(0.1, 10, 10)
contour = ax.contour(X, Y, Z, levels=levels)

# 添加轮廓线标签
ax.clabel(contour, inline=True, fontsize=8)

plt.show()

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.collections import QuadContourSet

# 创建数据
x = np.linspace(-3, 3, 100)
y = np.linspace(-3, 3, 100)
X, Y = np.meshgrid(x, y)
Z = X**2 + Y**2

# 生成轮廓
fig, ax = plt.subplots()
contour = ax.contour(X, Y, Z)

# 删除0级线
for collection in contour.collections:
    if isinstance(collection, QuadContourSet):
        for path in collection.get_paths():
            vertices = path.vertices
            # 检查路径是否闭合且面积接近0（即0级线）
            if np.isclose(vertices[0], vertices[-1]).all() and path.contains_point((0, 0)):
                collection.remove_path(path)

plt.show()

pip install matplotlib