python连接高斯数据库_Python加载数据并执行多高斯fi
簡單制作單高斯和的參數化模型函數。為最初的猜測選擇一個好的值(這是一個非常關鍵的步驟),然后讓scipy.optimize稍微調整一下這些數字。
你可以這樣做:import numpy as np
import matplotlib.pyplot as plt
from scipy import optimize
data = np.genfromtxt('data.txt')
def gaussian(x, height, center, width, offset):
return height*np.exp(-(x - center)**2/(2*width**2)) + offset
def three_gaussians(x, h1, c1, w1, h2, c2, w2, h3, c3, w3, offset):
return (gaussian(x, h1, c1, w1, offset=0) +
gaussian(x, h2, c2, w2, offset=0) +
gaussian(x, h3, c3, w3, offset=0) + offset)
def two_gaussians(x, h1, c1, w1, h2, c2, w2, offset):
return three_gaussians(x, h1, c1, w1, h2, c2, w2, 0,0,1, offset)
errfunc3 = lambda p, x, y: (three_gaussians(x, *p) - y)**2
errfunc2 = lambda p, x, y: (two_gaussians(x, *p) - y)**2
guess3 = [0.49, 0.55, 0.01, 0.6, 0.61, 0.01, 1, 0.64, 0.01, 0] # I guess there are 3 peaks, 2 are clear, but between them there seems to be another one, based on the change in slope smoothness there
guess2 = [0.49, 0.55, 0.01, 1, 0.64, 0.01, 0] # I removed the peak I'm not too sure about
optim3, success = optimize.leastsq(errfunc3, guess3[:], args=(data[:,0], data[:,1]))
optim2, success = optimize.leastsq(errfunc2, guess2[:], args=(data[:,0], data[:,1]))
optim3
plt.plot(data[:,0], data[:,1], lw=5, c='g', label='measurement')
plt.plot(data[:,0], three_gaussians(data[:,0], *optim3),
lw=3, c='b', label='fit of 3 Gaussians')
plt.plot(data[:,0], two_gaussians(data[:,0], *optim2),
lw=1, c='r', ls='--', label='fit of 2 Gaussians')
plt.legend(loc='best')
plt.savefig('result.png')
如您所見,這兩種配合(視覺上)幾乎沒有區別。所以你不能確定源中是否有3個高斯子,或者只有2個高斯子。但是,如果您必須進行猜測,請檢查最小的殘差:err3 = np.sqrt(errfunc3(optim3, data[:,0], data[:,1])).sum()
err2 = np.sqrt(errfunc2(optim2, data[:,0], data[:,1])).sum()
print('Residual error when fitting 3 Gaussians: {}\n'
'Residual error when fitting 2 Gaussians: {}'.format(err3, err2))
# Residual error when fitting 3 Gaussians: 3.52000910965
# Residual error when fitting 2 Gaussians: 3.82054499044
在這種情況下,3高斯給出了一個更好的結果,但我也使我的初步猜測相當準確。
總結
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