MATLAB: How to read a txt file with known structure

char to matrixhowhow to read text filereadfile

Hello, How to read a file that has given structure?

boundary -5.0 -5.0 5.0 15.0
block  -3.0  1.0  3.0  1.25
block  -3.0  1.0  -2.75  10.0
block  2.75  1.0  3.0  10.0

I want array or matrix of first four digits e.g

boundary=[-5.0 -5.0 5.0 15.0],

and in the block should look like this

block=[ -3.0  1.0  3.0  1.25;-3.0  1.0  -2.75  10.0]

Number of rows is not constant but number of columns are constant so at the end, it should show me

boundary =
       0     0     5     4
blocks =
       1     1     2     2
       2     2     4     3

Thanks

Best Answer

fid = fopen('map1.txt');
boundary = fscanf(fid, 'boundary %f%f%f%f', 1);
blocks = cell2mat( textscan(fid, 'block %f%f%f%f', 'CollectOutput', true) );
fclose(fid);

Related Solutions

MATLAB: Reading big textfile with textscan

Solution One

You do not need to delete the first ten rows from the file, because textscan has an option to ignore header lines, so you can use this instead:

Out = textscan(....,'HeaderLines',10);

To read 1280 columns of data you need to define this in the format string, so the final code could be something like this:

fmt = repmat('%f',1,1280);
fid = fopen('textfile.txt','rt')
out = textscan(fid, fmt, 'Delimiter',',', 'HeaderLines',10);
fclose(fid);

Solution Two

If the data in the matrix is all numeric (note the header lines do not need to be) then you could use the much simpler dlmread instead, something a bit like this:

out = dlmread('textfile.txt',',',10,0);

Examples

% textscan
fmt = repmat('%f',1,5);
fid = fopen('temp.txt','rt');
out_txt = textscan(fid, fmt, 'Delimiter',',', 'HeaderLines',3);
fclose(fid);
out_txt = cell2mat(out_txt)
% dlmread
out_dlm = dlmread('temp.txt',',',3,0)

display this in the command window:

out_txt =
     0     1     2     3     4
     5     6     7     8     9
out_dlm =
     0     1     2     3     4
     5     6     7     8     9

The sample text file that I used is attached here:

MATLAB: Reading text number combination with comma delimiter

solved, just for reference the following works

textscan(fileID,'%s %f %f %f\n','delimiter',',')

Best Answer

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MATLAB: Reading big textfile with textscan

MATLAB: Reading text number combination with comma delimiter

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