a contains indices and their occurrences. Now the indexing needs to be changed with Hamming weight so that indices with equal hamming weight will be summed up. How to do the Hamming weight indexing? Any ready command for this in Matlab?
>> a=[1,2;2,3;5,2;10,1;12,2]
1 2
2 3
5 2
10 1
12 2
13 8
>> dec2bin(a(:,1))
ans =
0001
0010
0101
1010
1100
1101
Goal: index things by Hamming weight
HW Count
1 5 (=2+3)
2 5 (=2+1+2)
3 8 (=8)
You can do it as follows:
a = [1,2;2,3;5,2;10,1;12,2;13,8]
the following line needs to be added, to consider also a hammingweight of zero:
if nnz(a(:,1)) == numel(a(:,1)); a = [0,0;a]; end
% or just
a = [0,0;a]; %// wouldn't change the result
to get the indices
rowidx = sum( de2bi(a(:,1)), 2 )
to get the sums
sums = accumarray( rowidx+1, a(:,2) ) %// +1 to consider Hammingweight of zero
to get the Hammingweight vector
HW = unique(rowidx)
returns:
rowidx =
1
1
2
2
2
3
sums =
5
5
8
and all together:
result = [HW, sums]
%or
result = [unique(rowidx), accumarray(rowidx+1,a(:,2))]
result =
0 0
1 5
2 5
3 8
If you are bothered by the 0 0 line, filter it out
result(sum(result,2)>0,:)
The result for a = [0,2;2,3;5,2;10,1;12,2;13,8] would be:
result =
0 2
1 3
2 5
3 8