使用Matplotlib绘制多组圆形Patches仅显示最后一组的问题求助

我尝试在单个Matplotlib图中绘制多组以不同中心定位的圆形集合，编写了生成圆形补丁（Patch）的函数，并将所有补丁存入total_patches列表。但将这些补丁添加到图中后，仅能看到最后一组圆形。

当前效果 #

期望效果 #

以下是我的代码：

def add_circles(center, radius_gt, area_pred, area_db):
    # fig, ax = plt.subplots()#figsize = (10,10)) # note we must use plt.subplots, not plt.subplot

    circle = plt.Circle(center, (radius_gt/2), facecolor='None', alpha=1, linewidth=1.5, linestyle='--', edgecolor='g')
    circle_pred = plt.Circle(center, gen_diameter(area_pred)/2, color='blue')
    circle_db = plt.Circle(center, gen_diameter(area_db)/2, color='r')
    
    patches = [circle_db, circle_pred, circle]
            
    return center, patches

total_patches = []

center = [5,0]
center, patches = add_circles(center, 3, average_3_pred, average_3_db)
[total_patches.append(patch) for patch in patches]
print(center)
# [ax.add_patch(patch) for patch in patches]

center[0] = center[0] + (5 + gen_diameter(average_3_db)/2 + gen_diameter(average_4_db)/2)
center, patches = add_circles(center, 4, average_4_pred, average_4_db)
[total_patches.append(patch) for patch in patches]
print(center)
# [ax.add_patch(patch) for patch in patches]

center[0] = center[0] + (5 + gen_diameter(average_4_db)/2 + gen_diameter(average_6_db)/2)
center, patches = add_circles(center, 6, average_6_pred, average_6_db)
[total_patches.append(patch) for patch in patches]
print(center)
# [ax.add_patch(patch) for patch in patches]

center[0] = center[0] + (5 + gen_diameter(average_6_db)/2 + gen_diameter(average_7_db)/2)
center, patches = add_circles(center, 7, average_7_pred, average_7_db)
[total_patches.append(patch) for patch in patches]
print(center)
# [ax.add_patch(patch) for patch in patches]

center[0] = center[0] + (5 + gen_diameter(average_7_db)/2 + gen_diameter(average_9_db)/2)
center, patches = add_circles(center, 9, average_9_pred, average_9_db)
[total_patches.append(patch) for patch in patches]

fig, ax = plt.subplots()#figsize = (10,10)) # note we must use plt.subplots, not plt.subplot

[ax.add_patch(patch) for patch in total_patches]

ax.set_aspect('equal')
ax.set_xlim(0,80)
ax.set_ylim(-10,10)

问题出在可变对象的引用特性上：你使用的center是列表（可变类型），每次修改center[0]时，之前创建的所有plt.Circle对象里的中心参数都会被同步修改——因为plt.Circle保存的是对这个列表的引用，而非列表的副本。最终所有圆形的中心都变成了最后一次修改后的位置，所以看起来只有最后一组圆形。

修复方法有两种，核心都是让每个圆形持有独立的中心坐标：

方法1：在add_circles函数内创建中心副本 #

将传入的center转换为不可变的元组，或者创建列表副本，确保后续修改原center不会影响已生成的圆形：

def add_circles(center, radius_gt, area_pred, area_db):
    # 创建中心副本，切断与原列表的引用关联
    center_copy = tuple(center)
    circle = plt.Circle(center_copy, (radius_gt/2), facecolor='None', alpha=1, linewidth=1.5, linestyle='--', edgecolor='g')
    circle_pred = plt.Circle(center_copy, gen_diameter(area_pred)/2, color='blue')
    circle_db = plt.Circle(center_copy, gen_diameter(area_db)/2, color='r')
    
    patches = [circle_db, circle_pred, circle]
            
    return center, patches

方法2：调用函数时传递中心副本 #

在每次调用add_circles前，传递center的副本而非原列表：

center = [5,0]
# 传递center的副本
center, patches = add_circles(center.copy(), 3, average_3_pred, average_3_db)
[total_patches.append(patch) for patch in patches]

# 后续调用同样传递副本
center[0] = center[0] + (5 + gen_diameter(average_3_db)/2 + gen_diameter(average_4_db)/2)
center, patches = add_circles(center.copy(), 4, average_4_pred, average_4_db)
[total_patches.append(patch) for patch in patches]

两种方法都能让所有组的圆形正确显示在各自的位置上。

内容的提问来源于stack exchange，提问作者user3165683