尝试 plot 时在赋值之前引用的局部变量

Question

I have the following code

from math import floor
import matplotlib.pyplot as plt 
import numpy as np 



def drive(n, n2all, sofar):
    assert n > 0
    if n == 1:
        result = n2all[1]
    else:
        result = set()
        push = result.add
        for i in range(1, n//2 + 1):
            for x in n2all[i]:
                for y in n2all[n-i]:
                    for z in x+y, x*y:
                        if z not in sofar:
                            push(z)
    return result



def e(n):
    n2all = {1: set([1])}
    sofar = set([1])
    for i in range(1, n):
        this = drive(i, n2all, sofar)
        n2all[i] = this
        sofar |= this
    return min(list(this))




def E(n):
    k = floor(n / 3)
    if n ==1:
        return 1
    if n % 3 == 0:
        return 3 ** k
    if n % 3 == 1:
        return 4 * 3**(k-1)
    if n % 3 == 2:
        return 2 * 3**k


def func(n):
    return e(n) / E(n)

and I want to get a picture of distribution of func(n). But whenever I try to calculate a values of func

n = 30
values = [func(i) for i in range(1, n)]

I get the following error

local variable 'this' referenced before assignment

Or are there any other way to plot a hist or a line of this function?

Answer 1

I think the problem lies in the e() function. The for loop need to be like so::

def e(n):
    n2all = {1: set([1])}
    sofar = set([1])
    for i in range(1, n+1):   #< ---just change this
    ...