Add data of a matrix based on an other matrix
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Philipp Wirtz
il 11 Mag 2018
Commentato: Philipp Wirtz
il 11 Mag 2018
I would like to add a certain amount of data points of one matrix in a new matrix, based on a third matrix. It is because I need to add data points from one day (it is not predefined how many datapoints there are going to be) and then go to the next day and do the same. This is the code I tried for now.
if true
% code
A = [1 1 1 2 2 2 3 4 5 6 6 6 7 8 9 10]; % Matrix that tells from which day data point of B is
B = rand(1,16).*100; % random data times 100 to get bigger numbers
i = 1; % variable used in the while loop
j = 1; % variable used in the while loop
C = []; % new matrix to store the summed data points for each day (it should become a 1x10 matrix in this specific case
while A(i) == i
while A(i) == i
C(1,i) = C(1,i) + B(1,j)
j = j + 1;
end
i = i + 1;
end
end
Hoping to find an answer. - Philipp
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Risposta accettata
Stephen23
il 11 Mag 2018
Modificato: Stephen23
il 11 Mag 2018
>> A = [1 1 1 2 2 2 3 4 5 6 6 6 7 8 9 10];
>> B = rand(1,16);
>> C = accumarray(A(:),B(:))
C =
1.090191
1.127991
0.044079
0.483190
0.890956
0.136439
0.025175
0.364094
0.165231
0.917592
>> size(C)
ans =
10 1
For MATLAB releases >= R2015b you could use splitapply.
Più risposte (2)
Cathal Cunningham
il 11 Mag 2018
Use logical indexing to do this
% Pre-build array
C = zeros(1,size(unique(A),2));
for i = 1:length(C)
C(i) = sum(B(A==i));
end
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