Can't draw function using python

Question

I have made a function RC(n) that given any n changes the digits of n according to a rule. The function is the following

def cfr(n):
    return len(str(n))-1


def n_cfr(k,n):
    J=str(k)
    if "." in J:
        J2=J.replace(".", "")
        return J2[n-1]
    else:
        return J[n]

def RC(n):
    if "." not in str(n): 
        return n+1
    sum=0
    val=0
    for a in range(1,cfr(n)+1):
        O=(int(n_cfr(n,a)))*10**(-a+1)
        if int(n_cfr(n,a))==9:
            val=0
        else:
            val=O+10**(-a+1)
        sum=sum+val
    return sum    

I would like to draw this function for non-integers values of n. A friend gave me this code that he used in other functions but it doesn't seem to work for me:

def draw(f,a,b,res):
import numpy as np
import matplotlib.pyplot as plt
    x=[a+(b-a)*i/res for i in range(0,res)]
    y=[f(elm) for elm in x]
    plt.plot(np.asarray(x), np.asarray(y))
    plt.show()

I'm not familiar with plotting functions using python so could anyone give me some help? Thanks in advance

Answer 1

The line in your function should be x = list(range(a, b, res)) the first two arguments of range are start and stop. Here is a better version of draw:

def draw(f, a, b, res):
    import numpy as np
    import matplotlib.pyplot as plt
    x = list(range(a, b, res))
    plt.plot(x, map(f, x))
    plt.show()