Error with arrays/matrix operations
<p>I am trying to run the following code.  For those who know it, this is a try of the Ehrenfest Urn simulation.</p>

<pre><code>import numpy as np
import random

C=5
L=2
# Here I create a matrix to be filled with zeros and after with numbers I want
b=np.zeros( (L,C) ) # line x column

A=[] # here I creat 2 lists to put random integer numbers on it
B=[]

i=1
while i&lt;=10: # here I am filling list A (only) with 10 numbers
    A.append(i)
    i=i+1

for j in range(2):

    for i in range(5):  #here I want to choose random numbers between 1 and 10,

        Sort=random.randint(1,10)

        if i==0: # since there is no number on B, the first step, the number goes to B
            B.append(Sort)
            A.remove(Sort)
            print(len(A))

        if i&gt;0:   # now each list A and B have numbers on it, so I will choose one number and see in which list it is
                if Sort in A:
                    B.append(Sort)
                    A.remove(Sort)
                else:
                    A.append(Sort)
                    B.remove(Sort)

            i=i+1
            b[j,i]=len(A) # here I want to add the lenght of the list A in a matrix, but then I get the error.
        j=j+1

print(b)
</code></pre>

<p>But I get the following error:</p>

<pre class="lang-none prettyprint-override"><code>Traceback (most recent call last):

  File "&lt;ipython-input-26-4884a3da9648&gt;", line 1, in &lt;module&gt;
runfile('C:/Users/Public/Documents/Python Scripts/33.py', wdir='C:/Users/Public/Documents/Python Scripts')

  File "C:\Program Files\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 866, in runfile
execfile(filename, namespace)

  File "C:\Program Files\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 102, in execfile
exec(compile(f.read(), filename, 'exec'), namespace)

  File "C:/Users/Public/Documents/Python Scripts/33.py", line 42, in &lt;module&gt;
b[j,i]=len(A) # here I want to add the lenght of the list A in a matrix

IndexError: index 5 is out of bounds for axis 1 with size 5
</code></pre>

<p>What am I doing wrong with the arrays?
Is there anything to do with the identification of the numbers in the matrix?</p>