报错：Font family [‘sans-serif’] not found. Falling back to DejaVu Sans Mac
解决办法：换自带的字体，不用SimHei

from matplotlib.font_manager import FontManager
fm = FontManager()
mat_fonts = set(f.name for f in fm.ttflist)
print(mat_fonts)

plt.rcParams['font.sans-serif'] = ['Songti SC']  # 用来正常显示中文标签
#plt.rcParams['font.family'] = ['sans-serif']
#图片显示中文
plt.rcParams['axes.unicode_minus'] =False #减号unicode编码