python 绘制拟合曲线并加指定点标识

import osimport numpy as npfrom scipy import logfrom scipy.optimize import curve_fitimport matplotlib.pyplot as pltimport mathfrom sklearn.metrics import r2_score# 字体plt.rcParams['font.sans-serif']=['SimHei']# 拟合函数def func(x, a, b):# y = a * log(x) + b y = x/(a*x+b) return y# 拟合的坐标点x0 = [2, 4, 8, 10, 24, 28, 32, 48] y0 = [6.66,8.35,10.81,11.55,13.63,13.68,13.69,13.67]# 拟合，可选择不同的methodresult = curve_fit(func, x0, y0,method='trf')a, b = result[0] # 绘制拟合曲线用x1 = np.arange(2, 48, 0.1) #y1 = a * log(x1) + by1 = x1/(a*x1+b)x0 = np.array(x0)y0 = np.array(y0)# 计算r2y2 = x0/(a*x0+b)#y2 = a * log(x0) + br2 = r2_score(y0, y2) #plt.figure(figsize=(7.5, 5)) # 坐标字体大小plt.tick_params(labelsize=11) # 原数据散点plt.scatter(x0,y0,s=30,marker='o')# 横纵坐标起止plt.xlim((0, 50))plt.ylim((0, round(max(y0))+2))# 拟合曲线plt.plot(x1, y1, "blue") plt.title("标题",fontsize=13) plt.xlabel('X（h）',fontsize=12) plt.ylabel('Y（%）',fontsize=12) # 指定点，y=9时求xp = round(9*b/(1-9*a),2)#p = b/(math.log(9/a))p = round(p, 2)# 显示坐标点plt.scatter(p,9,s=20,marker='x')# 显示坐标点横线、竖线plt.vlines(p, 0, 9, colors = "c", linestyles = "dashed")plt.hlines(9, 0, p, colors = "c", linestyles = "dashed")# 显示坐标点坐标值plt.text(p, 9, (float('%.2f'% p),9),ha='left', va='top', fontsize=11)# 显示公式m = round(max(y0)/10,1)print(m)plt.text(48, m, 'y= x/('+str(round(a,2))+'*x+'+str(round(b,2))+')', ha='right',fontsize=12) plt.text(48, m, r'$R^2=$'+str(round(r2,3)), ha='right', va='top',fontsize=12) # True 显示网格 # linestyle 设置线显示的类型(一共四种) # color 设置网格的颜色 # linewidth 设置网格的宽度 plt.grid(True, linestyle = "--", color = "g", linewidth = "0.5")plt.show()

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