Insert specific number of rows of zeroes(5) after every 56 rows in my n*m matrix. I am able to create matrices but can I do the insertion without loop given I know the size of matrix? Thanks for help

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I have a huge 2464 * 2484 matrix that I want to manipulate and make 2684*2684 but I need the new 220 rows to be divided into 5 rows after every 56 rows of original matrix. I am able to think of loop code --
>> A=csvread('InputWIODRaw.csv');
>> A=csvread('InputWIODRaw.csv');
>> B= zeros(5,2684);
>> CountryVar = [56:56:2464];
>> for i = 1:44
if i==1
j=1;
elseif i>1
j=CountryVar(i-1)+1;
end
ReorderMatrix(i)= A(j:CountryVar(i),:);
Reorder(i) = [ReorderMatrix(i); B];
end
error: =: nonconformant arguments (op1 is 1x1, op2 is 56x2684)
>> for i = 1:44
if i==1
j=1;
elseif i>1
j=CountryVar(i-1)+1;
end
ReorderMatrix(i) = zeros(56,2684);,2684)= A(j:CountryVar(i),:);
parse error:
syntax error
>>> ReorderMatrix(i) = zeros(56,2684);,2684)= A(j:CountryVar(i),:);
^
>> ReorderMatrix(i) = zeros(56,2684);
error: =: nonconformant arguments (op1 is 1x1, op2 is 56x2684)
But not sure how to initialize. Is there a better way if not how to rectify this code? Much appreciated

Respuesta aceptada

Kelly Kearney
Kelly Kearney el 22 de Mzo. de 2018
Another approach, which works even if your data doesn't divide evenly:
x = rand(21,6);
nrow = 5; % number of rows of data in each group
nlines = 2; % number of rows of 0s to add after each group
nsets = floor(size(x,1)./nrow);
nextra = rem(size(x,1), nrow);
x = mat2cell(x, [ones(nsets,1)*nrow; nextra], size(x,2));
x = cellfun(@(x) [x; zeros(nlines, size(x,2))], x, 'uni', 0);
x = cat(1, x{:});

Más respuestas (1)

Guillaume
Guillaume el 22 de Mzo. de 2018
You can indeed do it without a loop.
  1. transpose the matrix so that your rows are columns (since matlab works by column)
  2. reshape the matrix so that each group of your original 56 rows are now a single column. Thus you end up with a matrix of 44 columns
  3. vertically concatenate this reshaped matrix with a zero matrix of height 5*width of original matrix and of width 44
  4. reshape the result back into the right number of rows and columns and transpose back
A = csvread('InputWIODRaw.csv');
B = A.';
B = reshape(B, 56*size(A, 2), []);
B = [B; zeros(5*size(A, 1), size(B, 2))];
B = reshape(B, size(A, 2), []);
B = B.';
  1 comentario
Siddhartha Sharma
Siddhartha Sharma el 23 de Mzo. de 2018
Thanks Guillaume, Although due to some reason the reshape size is throwing errors and the reverse transpose is not happening so I end up with 16800 columns.

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