如何使用热图seaborn subplot Python 3.6.0中的不同间隔值自定义cmap中的每种颜色？

import seaborn as sns
import matplotlib.pyplot as plt

data = [[1, 2, 3],
        [4, 5, 6],
        [7, 8, 9]]

cmap = sns.diverging_palette(220, 10, as_cmap=True)

fig, ax = plt.subplots()
sns.heatmap(data, cmap=cmap, annot=True, fmt=".1f", linewidths=.5, ax=ax)

cbar = ax.collections[0].colorbar
cbar.set_ticks([1, 2, 3, 4, 5, 6, 7, 8, 9])
cbar.set_ticklabels(['Low', 'Medium', 'High'])

import seaborn as sns
import matplotlib.pyplot as plt

data = [[1, 2, 3],
        [4, 5, 6],
        [7, 8, 9]]

cmap = sns.diverging_palette(220, 10, as_cmap=True)

fig, ax = plt.subplots()
sns.heatmap(data, cmap=cmap, annot=True, fmt=".1f", linewidths=.5, ax=ax)

cbar = ax.collections[0].colorbar
cbar.set_ticks([1, 2, 3, 4, 5, 6, 7, 8, 9])
cbar.set_ticklabels(['Low', 'Medium', 'High'])

plt.show()