CODEWITHSUNDEEP
pythonarraysmatlabnumpyindexing
Brandon Ginley
Brandon Ginley

Reputation: 269

Converting MATLAB to Python: too many indices return error

I am attempting to convert a script I have in MATLAB to Python in order to increase speed and efficiency of the overall algorithm. In MATLAB, the code is as follows:

for iter = 1:T
costi = costo;
for i = 1:length(index)
    for j = i+1:length(index)
        if index(j) == index(i)
            continue;
        end
        indexdn = indexd;
        indadd = (index(j) - index(i));
        indexdn(:,j) = indexdn(:,j) + indadd;
        ##line 11
        indexdn(j,:) = -indexdn(:,j)';            
        indexdn(j,j) = 0;
        indi = abs(indexdn);
        indi = ~indi;
        costnb = costmata.*indi;
        costn = 0.5*(sum(sum(costnb)));
        if costn < costi
            costi = costn;
            index(j) = index(i);
            indexd = indexdn;
        end
    end
end
if costi < costo
    costo = costi;
else 
    break
end
iter
end

I have completed most of the translation:

for j in range(0,T):
cost2 = cost1
for x in xrange(len(index)):
    for y in xrange(x+1,len(index)):
        if index[y] == index[x]:
            continue
        indexdn = indexd
        indadd= index[y]-index[x]
        print indadd
        indexdn[:,y]=indexdn[:,y]+ indadd
        index[y,:]=-indexdn[:,y] ##line 11, return error
        indexdn[y,y]=0
        indi= np.abs(indexdn)
        indi= ~indi
        costnb = costmata*indi
        costn = .5(np.sum(costnb))
        if (costn < cost2):
            costi=costn;
            index[y] = index[x]
            indexd= indexdn
if cost2<cost1:
    cost1=cost2
else:
    break

however, on line 11, I am returned an error of "index error: too many indices." What is causing Python to get tripped up on this line? How can I write my Python code so that I am not returning this error? index array is a numpy array predefined with length 16 with random integers 0-5, indexd array is a 16x16 array with random integers -5 to 5, and indexdn,indadd are being created within this iteration.

Upvotes: 2

Views: 83

Answers (1)

tmdavison
tmdavison

Reputation: 69116

It looks like index is a 1-d array? (you have index[y] and index[x] on line 5 and 8, and say it is of length 16)

But, on line 11, you are trying to access its second dimension: index[y,:]. Maybe that should be indexdn[y,:] =-indexdn[:,y]?

Upvotes: 3

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