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how to read a textfile that contain an array of text values into matrix

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Yoav Weizman
Yoav Weizman on 16 Mar 2017
Commented: Walter Roberson on 2 Jun 2017
I have a textfile that contain tab delimited hexadecimal values and I would like to transfer the values into an array with each element will keep a value in the table (attached)

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Answers (4)

Massimo Zanetti
Massimo Zanetti on 16 Mar 2017
Edited: Massimo Zanetti on 16 Mar 2017
Here is it, you should know how many columns your data span (I guessed by reading your file they are 25):
%open file
fname = 'PowerUpRampSpeed_1.txt';
fileID = fopen(fname);
%read formatted data as strings of 2 characters
A = textscan(fileID,'%2c','Delimiter','\t');
%reshape the vector to matrix size
cols = 25;
A = reshape( hex2dec(char(A)) , cols , [])';
%close file
fclose(fname);
Now, A is your matrix read into Matlab.

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Jan
Jan on 16 Mar 2017
Edited: Jan on 16 Mar 2017
fname = 'file.txt';
fid = fopen(fname, 'r');
if fid == -1
error('Cannot open file for reading: %s', fname);
end
A = fscanf(fid, '%2x', [25, inf]).';
fclose(fid);
The conversion of hexadecimal number is much faster in fscanf/sscanf then by hex2dec.

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Yoav Weizman
Yoav Weizman on 20 Mar 2017
Edited: per isakson on 2 Jun 2017
Thanks Jan and Massimo
I managed to find the following solution and it worked
array=reshape(textread('filename','%s'),200,32);
I was wondering if there is any reason to favor textscan or fscanf solutions?

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Jan
Jan on 21 Mar 2017
textscan is more powerful, fscanf is faster. If you have a running textscan version and import some dozens of files only, spending 15 minute to create a faster fscanf version is most likely a waste of time - a pre-mature optimization.
Walter Roberson
Walter Roberson on 2 Jun 2017
Your solution leaves the values as text. Were you wanting a text array, or were you wanting a numeric array?
Walter Roberson
Walter Roberson on 2 Jun 2017
Oddly, at least on OS-X, textread() is not able to read files with the original name PowerUpRampSpeed_1µs.txt claiming they do not exist . I will be filing a bug report on that.

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Walter Roberson
Walter Roberson on 2 Jun 2017
S = fileread('PowerUpRampSpeed_1µs.txt');
temp = regexp( regexp(S, '\r?\n', 'split'), '\W+', 'split');
output = vertcat(temp{:});
The result will be a 32 x 200 cell array of character vectors; hex values will not be converted to numeric.

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