how to split a vector into small subvectors based on condition

2020 3 15
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更新时间：2020 3 15
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how can i split a vector into smaller sub vectors, such that the sum of each vectors is less than N
N = 60
V = [30 35 24 15 14 48];

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Walter Roberson
Walter Roberson 2020-3-15
Putting everything into the same vector satisfies the stated conditions.
Elysi Cochin
Elysi Cochin 2020-3-15
very sorry, question edited, should not be greater was my question
Walter Roberson
Walter Roberson 2020-3-15
Breaking up into individual elements satisfies the stated conditions. There are other solutions too, but the question does not prevent the algorithm from being lazy and not even trying a different solution.

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Ameer Hamza
Ameer Hamza 2020-3-15
编辑：Ameer Hamza 2020-3-15

1 个投票

From your other question: https://www.mathworks.com/matlabcentral/answers/510716-compute-from-a-set-of-parameters. I suspect that you want to find all distinct combination of elements where the sum is less than 60 while keeping the number of trips to a minimum. The following code will find an optimal solution; however, it will only work if the number of elements of V is small (say less than 20). The solution have exponential time and space complexity, so the required resources will grow very quickly. For large number of variables, I would recommend using some greedy method, which can give a sub-optimal solution.
N = 60;
V = [30 35 24 15 14 48];
a = mat2cell(repmat([0 1], numel(V), 1), ones(size(V)), 2);
combs = logical(combvec(a{:})'); % create all possible combinations
combs(1, :) = []; % remove a trivial combination
cost = sum(combs.*V, 2);
valid_index = cost < N;
valid_combs = combs(valid_index, :);
valid_costs = cost(valid_index);
[valid_costs, index] = sort(valid_costs, 'descend');
valid_combs = valid_combs(index, :);
optimal_combs = logical([]);
while ~isempty(valid_combs)
current_comb = valid_combs(1,:);
optimal_combs = [optimal_combs; current_comb];
index = any(valid_combs(:, current_comb) == valid_combs(1, current_comb), 2);
valid_combs(index, :) = [];
end
result = {};
for i=1:size(optimal_combs,1)
result{i} = V(optimal_combs(i,:));
end

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Elysi Cochin
Elysi Cochin 2020-3-15
Sir why dont you post this answer in that link, so that i will accept it there, and it will add to your points
As i didnt get an answer to that question, i thought of splitting the question in a simple way
sir, the first Answer you gave, when i executed the code, its somewhat close,
i dont want repeatition of elements, once if i store a value into a new subvector , then i wont consider that value
my expected output is
{ [ 30 15 14] [ 35 24 ] [ 48] }
or do i need to use the second Answer to get the desired output?
Ameer Hamza
Ameer Hamza 2020-3-15
编辑：Ameer Hamza 2020-3-15
Elysi, my current code also gives the output you require. Check the value of result variable
result{1}
result{2}
result{3}
You will see there is no repetition. I posted this code in response to your other question too.
Elysi Cochin
Elysi Cochin 2020-3-15
编辑：Elysi Cochin 2020-3-15
Sir i was telling about repetition in this code
clear all
clc
V = [30 35 24 15 14 48]
N=60
for i=1:size(V,2)
subsA = nchoosek(V,i);
for j=1:size(subsA)
Sum=sum(subsA(j,:));
if Sum<N
G=subsA(j,:)
end
end
end
Ameer Hamza
Ameer Hamza 2020-3-15
Elysi, that answer was not from me. It was posted by Ahmed Anas.
Elysi Cochin
Elysi Cochin 2020-3-15
sorry sir for the confusion, now only saw the names were different
Thank you sir for your answers

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Ahmed Anas
Ahmed Anas 2020-3-15
编辑：Ahmed Anas 2020-3-15

0 个投票

Dear, it will give you the desired results
clear all
clc
V = [30 35 24 15 14 48]
N=60
for i=1:size(V,2)
subsA = nchoosek(V,i);
for j=1:size(subsA)
Sum=sum(subsA(j,:));
if Sum<N
G=subsA(j,:)
end
end
end

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Ahmed Anas
Ahmed Anas 2020-3-15
If you could not understand this code then please tell..
Walter Roberson
Walter Roberson 2020-3-15
I suspect that the sub-vectors are intended to be consecutive elements.
Elysi Cochin
Elysi Cochin 2020-3-15
sir, i executed the code, its somewhat close,
i dont want repeatition of elements, once if i store a value into a new subvector , then i wont consider that value
my expected output is
{ [ 30 15 14] [ 35 24 ] [ 48] }

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