Question

I have been trying to optimize this code:

def spectra(mE, a):
    pdf = lambda E: np.exp(-(a+1)*E/mE)*(((a+1)*E/mE)**(a+1))/(scipy.special.gamma(a+1)*E)
    u=[]
    n=np.random.uniform()
    E=np.arange(0.01,150, 0.1)
    for i in E: 
        u.append(scipy.integrate.quad(pdf,0,i)[0])

    f=interp1d(u, E)
    return f(n)

I was trying to create a lookup table out of f, but it appears that every time I call the function it does the integration all over again. Is there a way to put in something like an if statement, which will let me create f once for values of mE and a and then just call that afterwards?

Thanks for the help.

Cheers.

Answer 1

It sounds like what you want to do is return a known value if the function is re-called with the same (mE, a) values, and perform the calculation if the input is new.

That is called memoization. See for example What is memoization and how can I use it in Python? . Note that in modern versions of Python, you can create a decorator to apply the memoization of the function, which lets you be a little neater.