Random Number Error in Python

Question

I get a random number generating error such as,

Traceback (most recent call last): File "C:\Users\SONY\Desktop\deneme.py", line 34, in update(x) File "C:\Users\SONY\Desktop\deneme.py", line 12, in update x[j] = x[j] + uniform(-1.4,1.4) NameError: global name 'uniform' is not defined

My code is as follows

N = 20

N_cor = 25
N_cf = 25
a = 0.5
eps = 1.4

def update(x):
    for j in range(0,N):
        old_x = x[j]
        old_Sj = S(j,x)
        x[j] = x[j] + uniform(-eps,eps)
        dS = S(j,x) - old_Sj
        if dS>0 and exp(-dS)<uniform(0,1):
            x[j] = old_x

def S(j,x):
    jp = (j+1)%N
    jm = (j-1)%N
    return a*x[j]**2/2 + x[j]*(x[j]-x[jp]-x[jm])/a

def compute_G(x,n):
    g = 0
    for j in range(0,N):
        g = g + x[j]*x[(j+n)%N]
        return g/N


x=[]
for j in range(0,N):
    x.append(0.0)
    print"x(%d)=%f"%(j,x[j])
for j in range(0,5*N_cor):
    update(x)
for alpha in range(0,N_cf):
    for j in range(0,N_cor):
        update(x)
    for n in range(0,N):
        G[alpha][n] = compute_G(x,n)
for n in range(0,N):
    avg_G = 0
    for alpha in range(0,N_cf):
        avg_G = avg_G + G[alpha][n]
        avg_G = avg_G / N_cf
        print "G(%d) = %f"%(n,avg_G)

Can you help me about how can i generate a uniform random number in range (-eps,eps) ?

from random import uniform

inspectorG4dget
– inspectorG4dget

2015-10-20 19:56:30 +00:00
Commented Oct 20, 2015 at 19:56 — inspectorG4dget
– inspectorG4dget, Commented Oct 20, 2015 at 19:56

russOnXMaps · Accepted Answer · 2015-10-20 19:57:01Z

2

You need to import random at the beginning of your code and call

random.uniform(a, b)

rather than just uniform.

Python docs on random number library

https://docs.python.org/2/library/random.html

answered Oct 20, 2015 at 19:57

russOnXMaps

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Comments

Zach P · Accepted Answer · 2015-10-20 20:46:35Z

0

In the beginning of the code add the line from random import uniform This will cause you to call the uniform function of the random package every time you call uniform()

Another option is to add the line import random at the top of the file and replace every instance of uniform() with random.uniform()

answered Oct 20, 2015 at 20:46

Zach P

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