python matplotlib 注释文本箭头简单代码示例

import numpy as npimport matplotlib.pyplot as pltfig, ax = plt.subplots(figsize=(5, 5))ax.set_aspect(1)x1 = -1 + np.random.randn(100)y1 = -1 + np.random.randn(100)x2 = 1. + np.random.randn(100)y2 = 1. + np.random.randn(100)ax.scatter(x1, y1, color="r")ax.scatter(x2, y2, color="g")bbox_props = dict(boxstyle="round", fc="w", ec="0.5", alpha=0.9)ax.text(-2, -2, "Sample A", ha="center", va="center", size=20,    bbox=bbox_props)ax.text(2, 2, "Sample B", ha="center", va="center", size=20,    bbox=bbox_props)bbox_props = dict(boxstyle="rarrow", fc=(0.8, 0.9, 0.9), ec="b", lw=2)t = ax.text(0, 0, "Direction", ha="center", va="center", rotation=45,      size=15,      bbox=bbox_props)bb = t.get_bbox_patch()bb.set_boxstyle("rarrow", pad=0.6)ax.set_xlim(-4, 4)ax.set_ylim(-4, 4)plt.show()