Not splitting correctly?

Question

Toby Pendlebury 2016-12-13

0
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关闭： MATLAB Answer Bot 2021-8-20

Hi I have a DNA sequence that I am trying to randomise 1000 times and then store each result in a cell array. The randomisation and storing works fine, but then for each new R i want to split it up into chunks using R_split(X,:)=R(X:X+(n-1)) which i have previously used to split a sequence up into chunks and works fine. But this code at the moment just splits the 1000 results of R into two columns of 500 instead, can anyone help please?

S=1000  
  R=cell(1,S);
    N_R=floor(length(R)/n)
    for H=1:S;
        L=randperm(length(DNA_H));
        M=DNA_H(L);
        R{1,H}=M;
        for X=1:N_R
            R_split(X,:)=R(X:X+(n-1))
        end 
    end

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Jan 2016-12-13

You tell us, what the code does, but not, what you want it to do. We do not have the data and cannot run your code. I do not see the meaning of the X loop.

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Answer 1

Guillaume 2016-12-13

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Any reason that R is a cell array instead of a S*numel(DNA_H) matrix?

The problem with your algorithm is that R_Split does not depend on H, so you overwrite it at each step of the H loop. It's not clear what you're trying to do with the X loop.

At a guess:

dna = 'ATGC';
DNA_H = dna(randi(4, 1, 200));  %demo data
S = 1000;
R = DNA_H(cell2mat(arrayfun(@(~) randperm(numel(DNA_H)), (1:S).', 'UniformOutput', false)));  %create a matrix instead of cell array
n = 2;
N_R = floor(size(R, 1) / n);
splitrows = ones(1, n) * N_R;
leftover = mod(size(R, 1), n);
if leftover
   splitrows = [splitrows, leftover];
end
R_split = mat2cell(R, splitrows, size(R, 2))