Asked by Michael
on 6 May 2013

I am importing data from a txt file that has a column list of values. I would like to populate a matrix with these values in a looped way so that the matrix fills each column in a row with consecutive values from the txt list, then moves to the next row to fill each column with the next set of values, and so on. I need this to work with any number of values and matrix size, so that if there are a total of m*n values in the column list, the matrix produced will be of size m x n.

The data is read from a txt file comprising 4 columns of information, of which I am only interested in the 4th. The order of population is critical as two of the list columns give x & y spatial coordinates that are associated with each of the values in the 4th column.

Currently my code looks like this:

W = importdata('307_6_5.txt',' ',8);

hor_el = 6;

ver_el = 5;

MODE = zeros(ver_el+1, hor_el+1);

for k = 1:(hor_el+1)*(ver_el+1)

for i = 1:ver_el + 1;

for j = 1:hor_el + 1;

MODE(i,j) = W.data(k, 4);

end

end

end

I know this will be embarrassingly simple for someone who knows what they are doing but unfortunately my Matlab skills are still very poor. Any help would be much appreciated.

Thankyou.

Answer by Dr. Seis
on 6 May 2013

Edited by Dr. Seis
on 6 May 2013

Accepted Answer

You appear to be overwriting MODE for each k such that, at the end of the for loops, each element in MODE is equal to the last data value. What you may need to do is to create something for determining the row/column indices associated with each k. For example:

W = importdata('307_6_5.txt',' ',8);

hor_el = 6;

ver_el = 5;

rowIDX = 1;

colIDX = 1;

MODE = zeros(ver_el+1, hor_el+1);

for k = 1:(hor_el+1)*(ver_el+1)

MODE(rowIDX,colIDX) = W.data(k, 4);

colIDX = colIDX+1;

if colIDX > (hor_el + 1)

rowIDX = rowIDX+1;

colIDX = 1;

end

end

If you understand the way that works, then you should be able to replace all that with something that has the same effect but with less typing:

W = importdata('307_6_5.txt',' ',8);

hor_el = 6;

ver_el = 5;

MODE = reshape(W.data(:,4),hor_el+1,ver_el+1)';

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## 2 Comments

## Babak (view profile)

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## Michael (view profile)

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https://in.mathworks.com/matlabcentral/answers/74826-help-needed-rearranging-data-into-a-matrix#comment_147646

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