我想对两个独立的参数x和y进行曲线拟合。我想优化参数a，b和c。我尝试在scipy中使用curve_fit优化参数。但是我的参数没有得到优化。我使用了以下代码
xdata = [214.737191559, -5.64912101538e-36, 36.1372453686, 189.459700978, 233.562136902, 201.230228832, -5.59364882619e-36, -36.3232002416, -188.192199081, -212.837139143, -232.342545403, -200.699429716]
ydata = [-5.88273617837e-37, -211.536123799, -186.67108047, -35.9497006815, 200.282998159, 232.085860035, 213.44274878, 187.945919272, 35.7227474297, -6.00785257974e-37, -199.746844708, -230.856058666]
xdata = np.array(xdata)
ydata = np.array(ydata)
def func1(X,a,b,c):
x,y = X
# x = np.array(X[0])
# y = np.array(X[1])
n = 8
# % A = ydata
# % B = -xdata
# % C = xdata. - ydata
# % H = zdata
g = np.subtract(x,y)
I_0 = np.subtract(x,y) # x-y = C
I_1 = np.multiply(c,I_0) # c(x-y) = cC
I_2 = np.multiply(b,-x) #b(-x) = bB
I_3 = np.multiply(a,y) # aA
I3_0 = np.subtract(I_1,I_2) # cC-bB
I3_1 = np.subtract(I_3,I_1) # aA-cC
I3_2 = np.subtract(I_2,I_3) # bB-aA
I3_00 = np.multiply(I3_0,I3_1) # (cC-bB)(aA-cC)
I3_01 = np.multiply(I3_00,I3_2) # (cC-bB)(aA-cC)(bB-aA)
I3 = np.divide(I3_01,54) # (cC-bB)(aA-cC)(bB-aA)/54
I2_0 = np.power((I3_1),2) # (aA-cC)^2
I2_1 = np.power((I3_0),2) # (cC-bB)^2
I2_2 = np.power((I3_2),2) # (bB-aA)^2
I2_00 = np.add(I2_0,I2_1) # (aA-cC)^2 + (cC-bB)^2
I2_01 = np.add(I2_00,I2_2) # (aA-cC)^2 + (cC-bB)^2 + (bB-aA)^2
I2 = np.divide(I2_01,54) # ((aA-cC)^2 + (cC-bB)^2 + (bB-aA)^2)/54
th_0 = np.divide(I3,(np.power(I2,(3/2)))) # I3/(I2^(3/2))
# print(th_0)
th = np.arccos(np.clip((th_0),-1,1)) # arccos(I3/(I2^(3/2)))
# print(th)
ans_0 = np.divide(np.add((2*th),(np.pi)),6) # (2*th + pi)/6
ans_1 = np.divide(np.add((2*th),(3*np.pi)),6) # (2*th + 3*pi)/6
ans_2 = np.divide(np.add((2*th),(5*np.pi)),6) # (2*th + 5*pi)/6
ans_00 = np.multiply(np.cos(ans_0),2) # 2*cos((2*th + pi)/6)
ans_11 = np.multiply(np.cos(ans_1),2) # 2*cos((2*th + 3*pi)/6)
ans_22 = np.multiply(np.cos(ans_2),2) # 2*cos((2*th + 5*pi)/6)
ans_000 = np.power(np.absolute(ans_00),n) # (abs(2*cos((2*th + pi)/6)))^n
ans_111 = np.power(np.absolute(ans_11),n) # (abs(2*cos((2*th + 3*pi)/6)))^n
ans_222 = np.power(np.absolute(ans_22),n) # (abs(2*cos((2*th + 5*pi)/6)))^n
ans_0000 = np.add((np.power(np.absolute(ans_00),n)),(np.power(np.absolute(ans_11),n))) # (abs(2*cos((2*th + pi)/6)))^n + (abs(2*cos((2*th + 3*pi)/6)))^n
ans_1111 = np.add((ans_0000),(np.power(np.absolute(ans_22),n))) # (abs(2*cos((2*th + pi)/6)))^n + (abs(2*cos((2*th + 3*pi)/6)))^n + (abs(2*cos((2*th + 5*pi)/6)))^n
sna_0 = np.power(np.multiply(3,I2),(n/2)) # (3*I2)^(n/2) !!
sna_1 = 2*(np.power(190.,n)) # 2*(sigma^n) !!
sna_00 = np.multiply(sna_0,ans_1111)
sna_11 = np.subtract(sna_00,sna_1)
return sna_11
a, b, c = 1., 1., 1.
z = func1((xdata,ydata), a, b, c) * 1 + np.random.random(12) / 100
# initial guesses for a,b,c:
p0 = 8., 2., 7.
cfit = (curve_fit(func1, (xdata,ydata), z, p0))
cfit
我得到以下结果
(array([1., 1., 1.]),
array([[ 2.00165749e-32, -1.12390196e-32, -3.15983591e-33],
[-1.12390196e-32, 1.91794261e-32, -3.96062853e-33],
[-3.15983591e-33, -3.96062853e-33, 1.44218612e-32]]))
我没有获得优化的a，b和c。
答案 0 :(得分：0)
以下是一些示例代码，可能会帮助您入门。这将使用curve_fit拟合“ z = f（x，y）”曲面，并绘制3D散点图，3D表面图和轮廓图。请注意，您可以在3D图上按住鼠标键，然后旋转它们进行检查。
import numpy, scipy, scipy.optimize
import matplotlib
from mpl_toolkits.mplot3d import Axes3D
from matplotlib import cm # to colormap 3D surfaces from blue to red
import matplotlib.pyplot as plt
graphWidth = 800 # units are pixels
graphHeight = 600 # units are pixels
# 3D contour plot lines
numberOfContourLines = 16
def SurfacePlot(func, data, fittedParameters):
f = plt.figure(figsize=(graphWidth/100.0, graphHeight/100.0), dpi=100)
matplotlib.pyplot.grid(True)
axes = Axes3D(f)
x_data = data[0]
y_data = data[1]
z_data = data[2]
xModel = numpy.linspace(min(x_data), max(x_data), 20)
yModel = numpy.linspace(min(y_data), max(y_data), 20)
X, Y = numpy.meshgrid(xModel, yModel)
Z = func(numpy.array([X, Y]), *fittedParameters)
axes.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.coolwarm, linewidth=1, antialiased=True)
axes.scatter(x_data, y_data, z_data) # show data along with plotted surface
axes.set_title('Surface Plot (click-drag with mouse)') # add a title for surface plot
axes.set_xlabel('X Data') # X axis data label
axes.set_ylabel('Y Data') # Y axis data label
axes.set_zlabel('Z Data') # Z axis data label
plt.show()
plt.close('all') # clean up after using pyplot or else thaere can be memory and process problems
def ContourPlot(func, data, fittedParameters):
f = plt.figure(figsize=(graphWidth/100.0, graphHeight/100.0), dpi=100)
axes = f.add_subplot(111)
x_data = data[0]
y_data = data[1]
z_data = data[2]
xModel = numpy.linspace(min(x_data), max(x_data), 20)
yModel = numpy.linspace(min(y_data), max(y_data), 20)
X, Y = numpy.meshgrid(xModel, yModel)
Z = func(numpy.array([X, Y]), *fittedParameters)
axes.plot(x_data, y_data, 'o')
axes.set_title('Contour Plot') # add a title for contour plot
axes.set_xlabel('X Data') # X axis data label
axes.set_ylabel('Y Data') # Y axis data label
CS = matplotlib.pyplot.contour(X, Y, Z, numberOfContourLines, colors='k')
matplotlib.pyplot.clabel(CS, inline=1, fontsize=10) # labels for contours
plt.show()
plt.close('all') # clean up after using pyplot or else thaere can be memory and process problems
def ScatterPlot(data):
f = plt.figure(figsize=(graphWidth/100.0, graphHeight/100.0), dpi=100)
matplotlib.pyplot.grid(True)
axes = Axes3D(f)
x_data = data[0]
y_data = data[1]
z_data = data[2]
axes.scatter(x_data, y_data, z_data)
axes.set_title('Scatter Plot (click-drag with mouse)')
axes.set_xlabel('X Data')
axes.set_ylabel('Y Data')
axes.set_zlabel('Z Data')
plt.show()
plt.close('all') # clean up after using pyplot or else thaere can be memory and process problems
def func(data, a, alpha, beta):
t = data[0]
p_p = data[1]
return a * (t**alpha) * (p_p**beta)
if __name__ == "__main__":
xData = numpy.array([1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0])
yData = numpy.array([11.0, 12.1, 13.0, 14.1, 15.0, 16.1, 17.0, 18.1, 90.0])
zData = numpy.array([1.1, 2.2, 3.3, 4.4, 5.5, 6.6, 7.7, 8.0, 9.9])
data = [xData, yData, zData]
initialParameters = [1.0, 1.0, 1.0] # these are the same as scipy default values in this example
# here a non-linear surface fit is made with scipy's curve_fit()
fittedParameters, pcov = scipy.optimize.curve_fit(func, [xData, yData], zData, p0 = initialParameters)
ScatterPlot(data)
SurfacePlot(func, data, fittedParameters)
ContourPlot(func, data, fittedParameters)
print('fitted prameters', fittedParameters)
modelPredictions = func(data, *fittedParameters)
absError = modelPredictions - zData
SE = numpy.square(absError) # squared errors
MSE = numpy.mean(SE) # mean squared errors
RMSE = numpy.sqrt(MSE) # Root Mean Squared Error, RMSE
Rsquared = 1.0 - (numpy.var(absError) / numpy.var(zData))
print('RMSE:', RMSE)
print('R-squared:', Rsquared)
答案 1 :(得分：0)
def func1(coeff,x,y):
a = coeff[0]
b = coeff[1]
c = coeff[2]
...
return
x0 = np.array([1.0, 1.0, 1.0])
res_lsq = least_squares(func1, x0,loss='cauchy',f_scale=0.001,args=(xdata, ydata))
res_lsq.x