fitting exponential decay with no initial guessing

Question

Does anyone know a scipy/numpy module which will allow to fit exponential decay to data?

Google search returned a few blog posts, for example - http://exnumerus.blo

Answer 1

If your decay starts not from 0 use:

popt, pcov = curve_fit(self.func, x-x0, y)

where x0 the start of decay (where you want to start the fit). And then again use x0 for plotting:

plt.plot(x, self.func(x-x0, *popt),'--r', label='Fit')

where the function is:

    def func(self, x, a, tau, c):
        return a * np.exp(-x/tau) + c