我想用.set_facecolor()方法填充垂直渐变（白色到红色）的多边形。我使用matplotlib.colors.LinearSegmentedColormap定义了一个颜色Map图，但似乎不允许我直接将颜色Map图传递给.set_facecolor()这样的颜色设置方法。如果我只传递一种颜色，它会成功运行-我如何传递一个渐变以具有预期的行为，颜色范围从白色底部到红色顶部？
工作代码段，具有固定颜色：

import matplotlib.pyplot as plt
from matplotlib.collections import PatchCollection
from matplotlib.patches import Polygon
from  matplotlib import colors, patches
import numpy as np

fig,ax = plt.subplots(1)

patches = []

verts = np.random.rand(3,2)
polygon = Polygon(verts,closed=True)
patches.append(polygon)

collection = PatchCollection(patches)

ax.add_collection(collection)

collection.set_color("blue")

ax.autoscale_view()
plt.show()

不适用于自定义渐变的片段：

cmap = colors.LinearSegmentedColormap.from_list('white_to_red', ['white', 'red'])

fig,ax = plt.subplots(1)

patches = []

verts = np.random.rand(3,2)
polygon = Polygon(verts,closed=True)
patches.append(polygon)

collection = PatchCollection(patches)

ax.add_collection(collection)

collection.set_facecolor(cmap)

ax.autoscale_view()
plt.show()