MATLAB: Loading vectors with multiple dimensions from a .txt file

loading from .txt filevectors with multiple dimensions

I have saved vectors line by line to .txt file. Now i want to load them one by one. Problem is that, vectors have different dimensions and dimensions are unknown.

The .txt file that i'm using is similar to the testing2.txt which is generated by the following code.

 A  = rand(28,1);
 B = rand(15,1);
 C = rand(36,1);
 fid=fopen('testing2.txt','w');
 fprintf(fid, '%f ', A);
 fprintf(fid, '\n ');
 fprintf(fid, '%f ', B);
 fprintf(fid, '\n ');
 fprintf(fid, '%f ', C);
 fprintf(fid, '\n ');
 fclose(fid);

Can anyone help?? Thanks in advance.

Best Answer

Use fgetl() to read a line into a buffer. Use sscanf() to convert the line into numeric. Store in a cell array.

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MATLAB: How to change a specific line in a text file

Loading txt into a cell.
Then do whatever you want with the cell. In this example, line 69 will be 99.
Then write the cell into a txt.

% Read txt into cell A
fid = fopen('test.txt','r');
i = 1;
tline = fgetl(fid);
A{i} = tline;
while ischar(tline)
    i = i+1;
    tline = fgetl(fid);
    A{i} = tline;
end
fclose(fid);
% Change cell A
A{69} = sprintf('%d',99);
% Write cell A into txt
fid = fopen('test2.txt', 'w');
for i = 1:numel(A)
    if A{i+1} == -1
        fprintf(fid,'%s', A{i});
        break
    else
        fprintf(fid,'%s\n', A{i});
    end
end

MATLAB: How to use “save” matlab

for i=1:size(res_tAcc.data,1)
  fprintf(fid, '%f ', res_tAcc.time(i,1)); 
  fprintf(fid, '%f %f %f %f %f %f %f %f %f %f %f %f %f %f %f', ...
          res_tAcc.data(i,1)', res_tAcc.data(i,2)', res_tAcc.data(i,3)', ...
          res_tGyro.data(i,1)', res_tGyro.data(i,2)', ...
  ..

Index exceeds matrix dimensions.

Error in resample2 (line 44) fprintf(fid, '%f %f %f %f %f %f %f %f %f %f %f %f %f %f %f', res_tAcc.data(i,1)', ...

You're running the loop over size(res_tAcc.data,1) but there's no guarantee that the others are necessarily identically the same size -- it appears at least one isn't as large.

Use size() on all the arrays you're wanting to output and ensure they're all at least as long as the one you've use.

BTW, for simplicity, a couple of things -- use repmat to make format strings manageable--

fmt=repmat('%f',1,15);
fprintf(fid,fmt,...

You can find the repeat count programmatically as well to save manual counting.

Also, build the array and output in one pass...

fmt=repmat('%f',1,16);
fprintf(fid,fmt,[res_tAcc.time(:,1)    res_tAcc.data(:,1:3) res_tGyro.data(:,1:3)  ... 
 res_tMagn.data(:,1:3) res_tOr.data(:,1:3)  res_tRotQuatr.data(::3)].');

It would be even simpler and more regularly formatted if used dlmwrite or similar.

ERRATUM:

Also, build the array and output in one pass...

fmt=[repmat('%f',1,16) '\n'];

Forgot to add the newline...

Best Answer

Related Solutions

MATLAB: How to change a specific line in a text file

MATLAB: How to use “save” matlab

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