Translating from Matlab to Python. List index out of range.

Question

Does anyone knows why it's telling me list index out of range? I'm trying to "translate" a Matlab file and I created lists instead of cell arrays, the main problem now lies in the index, it seems correct to me and I don't know how there is an issue

#Projection operator Pi
piOperator = np.zeros((N*N, N*N)) 

#Psi0 state
Psi0 = np.zeros((N*N, 1))
for i in xrange(0 , N-1 ):
    aux = np.zeros((N,1)) #Auxiliary vector 
    aux[i]= 1
    A =  np.sqrt(G[:,i])
    psi = []
    P = [] 
    psi.append(np.tensordot(aux, A))
    P.append(np.dot(psi[i],np.transpose(psi[i])))
    piOperator = piOperator + P[i]
    Psi0 = Psi0 + psi[i] 


Psi0 = 1/np.sqrt(N)*Psi0 


---------------------------------------------------------------------------
IndexError                                Traceback (most recent call    last)
<ipython-input-450-0816498ad018> in <module>()
 11     P = []
 12     psi.append(np.tensordot(aux, A))
 ---> 13     P.append(np.dot(psi[i],np.transpose(psi[i])))
 14     piOperator = piOperator + P[i]
 15     Psi0 = Psi0 + psi[i]

 IndexError: list index out of range

The original Matlab code was:

Pi = zeros(n^2,n^2);
Psi0 = zeros(n^2,1);
for k=1:n
    aux = zeros(n,1);
    aux(k) = 1;
    psi{k} = kron(aux,sqrt(G(:,k)));
    P{k} = psi{k} * psi{k}';
    Pi = Pi + P{k};
    Psi0 = Psi0 + psi{k};
end
Psi0 = 1/sqrt(n)*Psi0;

Can you please post a complete code snippet? G is missing, for example. — csl
– csl, Commented Jun 16, 2017 at 8:55

Ivan · Accepted Answer · 2017-06-16 08:56:03Z

2

You are clearing your psi variable every iteration. Just initialize it before the loop:

#Projection operator Pi
piOperator = np.zeros((N*N, N*N)) 

#Psi0 state
Psi0 = np.zeros((N*N, 1))
psi = []
P = [] 
for i in xrange(0 , N-1 ):
    aux = np.zeros((N,1)) #Auxiliary vector 
    aux[i]= 1
    A =  np.sqrt(G[:,i])
    psi.append(np.tensordot(aux, A))
    P.append(np.dot(psi[i],np.transpose(psi[i])))
    piOperator = piOperator + P[i]
    Psi0 = Psi0 + psi[i] 


Psi0 = 1/np.sqrt(N)*Psi0

answered Jun 16, 2017 at 8:56

Ivan

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1 Comment

S.Azeglio Over a year ago

Thank you so much! I'm such a fool :)

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