Python: Index error when trying a[:,x] command on array

I am new to python so I am sorry if my formatting, etc is bad or if this question is trivial but I am trying to figure out why I am getting an index error in the third (and I assume second) to last lines of my code. I include the function just for context so you can see the QR function that the array I am calling is derived from. The command giving the index error works in the second line of the code but not the second to last. Can anyone explain why this is? I am thinking it has something to do with the fact that a_new is an array?

Also, from what I understand a[:,0] takes the first column from a matrix or array. If this understanding is not correct I would love to learn the right way to do this too.

Thanks!

a=np.random.random((3,3)); a
a[:,2]


###Gram-Schmidt operation for finding Q orthonormal matrix
###We begin with the reduced 3X3 case
def QR(a):  
     A0=a[:,0]; A0
     A1=a[:,1]; A1
     A2=a[:,2]; A2   

     Z0=A0
     Z1=A1-np.vdot(A1,A0)/np.vdot(A0,A0)*A0
     Z2=A2-np.vdot(A2,A0)/np.vdot(A0,A0)*A0-np.vdot(A2,Z1)/np.vdot(Z1,Z1)*Z1

     Z0norm=np.linalg.norm(Z0); Z0norm
     Z1norm=np.linalg.norm(Z1); Z1norm
     Z2norm=np.linalg.norm(Z2); Z2norm

     q0=Z0/Z0norm
     q1=Z1/Z1norm
     q2=Z2/Z2norm

     a_new=np.array([[q0],[q1],[q2]])

     return a_new

a_new=QR(a); a_new
a_new0=a_new[:,0]
a_new1=a_new[:,1]
g1=np.vdot(a_new1,a_new2); g1   

EDIT: Sorry! Here is the error message:

a_new0=a_new[:,0] a_new1=a_new[:,1] Traceback (most recent call last): File "", line 1, in IndexError: index 1 is out of bounds for axis 1 with size 1