MATLAB: How to import a spesific variable from a matrix in a file

fileimportmatrixreadspecifyvariable

I have a file "SANJOSE" that has two values in it "20 30"

I would like to use "loc1lat = importdata('SANJOSE')" command to import the first value of the 1×2 matrix, not the whole thing.

I am not sure what syntax to use after ('SANJOSE', ???) to specify which variable in the matrix I want.

Thanks

Best Answer

filename = 'SANJOSE';

(SANJOSE is a text file containing one line: 20 30)

Two options, either pass the file name SANJOSE as a string:

fid = fopen('SANJOSE','r'); %'r' means you only want to read the data. 
your_value = fscanf(fid,'%d',1); %Will only read the first value
fclose(fid);

Or, pass the variable name (filename) that contains a string:

fid = fopen(filename,'r');
your_alternative_value = fscanf(fid,'%d',1);
fclose(fid);

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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 read n first lines of a txt file and keep the format when writing the read data to the new (another) text file

To read into a cell array, line by line:

 fid = fopen(your_filename,'r');
 numLines = 4;
 your_text = cell(numLines,1);
 for ii = 1:numLines
     your_text(ii) = {fgetl(fid)}; 
 end
 fclose(fid);

And now to save:

 fid = fopen('your_file.txt','w');
 for ii = 1:numLines
     fprintf(fid,'%s\n',your_text{ii})
 end
 fclose(fis)
 your_first_value = fscanf(fid,'%d',1);
 fclose(fid);

Note that the return of carriage will be '\r\n' in Windows instead of just '\n'.

Best Answer

Related Solutions

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

MATLAB: How to read n first lines of a txt file and keep the format when writing the read data to the new (another) text file

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