用任意函数拟合数据，并在达到一定值时进行检查

Question

就像标题说的。我想符合这些要点。找到一个函数并检查我的函数将在哪个x处达到100。你知道吗

    import numpy as np
import matplotlib.pyplot as plt
from scipy.optimize import curve_fit



points = np.array([(3, 0), (7, 55), (14, 88)])
x = points[:,0]
y = points[:,1]
def func(x, p1,p2):
  return p1*np.log(x)+p2

popt, pcov = curve_fit(func, x, y,p0=(1.0,10.2))
print popt
p1 = popt[0]
p2 = popt[1]

curvex=np.linspace(15,85,1000)
fit = func(curvex, p1, p2)
plt.plot(x, y, 'yo', label='data')



plt.plot(curvex,fit,'r', linewidth=5)

plt.plot(x,y,'x',label = 'Xsaved')

plt.show()

1. 如何使函数通过点？（如果工作量过大，则不需要）

2. 如何得到y=100的x值？

谢谢！你知道吗

Answer 1

import numpy as np
import matplotlib.pyplot as plt
from scipy.optimize import curve_fit
from scipy.interpolate import interp1d


points = np.array([(3, 0), (7, 55), (14, 88)])
x = points[:,0]
y = points[:,1]
def func(x, p1,p2):
  return p1*np.log(x)+p2

popt, pcov = curve_fit(func, x, y,p0=(1.0,10.2))
print popt
p1 = popt[0]
p2 = popt[1]

curvex=np.linspace(15,85,1000)
fit = func(curvex, p1, p2)
plt.plot(x, y, 'yo', label='data')

f = interp1d(fit, curvex, kind = 'cubic')
print f(100)
plt.plot(curvex,fit,'r', linewidth=1)

plt.plot(x,y,'x',label = 'Xsaved')

plt.show()

这回答了我的问题。函数在x=16.54处穿过y=100。你知道吗