Loop for reading and extracting data from a single line of multiple text files.

I have the following code that I would like to put into a loop to read multiple text files.

txt = fileread('Test01.txt');
  temppos = strfind(txt,'Ground Temperature:');
  endpos = strfind(txt, '°C');

    for k = 1:numel(temppos)
        section{k,:} = txt(temppos(k):endpos(k));
    end

    for k = 1:numel(section)
        temp(k,:) = sscanf(section{k}, 'Ground Temperature: %f');
    end

    Results = table(temp, 'VariableNames',{'Temp'});

[James]

Please see the files attached.

[James]

Having issues saving multiple files. Could only save one. But the only thing changing in the data is the file name and the temp.

Answer 1

[Star Strider]

I generally do something like this —

files = dir('*.txt');

for k = 1:numel(files)
    txt = fileread(files(k).name);
    temppos = strfind(txt,'Ground Temperature:');
    endpos = strfind(txt, '°C');

    for k = 1:numel(temppos)
        section{k,:} = txt(temppos(k):endpos(k));
    end

    for k = 1:numel(section)
        temp(k,:) = sscanf(section{k}, 'Ground Temperature: %f');
    end

    Results{k} = table(temp, 'VariableNames',{'Temp'});
end

Results{:}

ans = table
    Temp
    ____

    29.3

This assumes the files are already in your working directory and on your MATLAB search path.

If that is not the situation in your application, you will need something like this:

files = dir('C:\PathName\*.txt')

and then:

filename{k} = fullfile('C:\PathName\',files(k).name)

text = fileread(filename{k});

or something similar. It may be neecessary for you to experiment a bit, depending on your situation.

EDIT — Corrected typographical errors.

.

[James]

Thank you for the response but, the code is only saving the last run .txt file. It is not appending the data from the previous files. Can you create 3 more files and just change the file name and the temp in the file?

[Star Strider]

My pleasure!

I created ‘Results’ here as a cell array. It should save all of them, and:

Results{:}

should be a cell array of the table arrays your code creates.

You can examine each one individually as:

Results{1}

Results{2}

...

Results{n}

and so forth, for as many as you have created.

If you want to concatenate them instead, the variable names in each havee to be different, so tthis lilne:

Results{k} = table(temp, 'VariableNames',{'Temp'});

becomes:

Results{k} = table(temp, 'VariableNames',{sprintf('Temp_%d',k)});

and then you can conatenate tthem after the loop with:

AllResults = horzcat(Results{:})

To illustrate:

for k = 1:5
    temp = round(rand*10,1);
    Results{k} = table(temp, 'VariableNames',{sprintf('Temp_%d',k)});
end
Results{:}

ans = table
    Temp_1
    ______

     4.2  

ans = table
    Temp_2
    ______

     2.7  

ans = table
    Temp_3
    ______

     6.5  

ans = table
    Temp_4
    ______

     9.1  

ans = table
    Temp_5
    ______

     5.9  

AllResults =  horzcat(Results{:})

AllResults = 1x5 table
    Temp_1    Temp_2    Temp_3    Temp_4    Temp_5
    ______    ______    ______    ______    ______

     4.2       2.7       6.5       9.1       5.9  

Try that. I’ll keep working with you until we get the result you want.

.

[James]

Thank you. I think there is something wrong with the counter in the for loops. They are all using the variable k. Can you share your code? As the code you supplied earlier is only outputting the value of the last text file.

[James]

These are the two additional files and their data. For some reason I’m not able to upload them as separate txt files to this question. If you could use this data and create a .txt for each and run your code. For me I’m only able to see one of the three files. It gives me an error of Index exceeds the number of array elements. Index must not exceed 1.

Thank you for your guidance.

Test

Test02

Software Version 1.2.4.1

Firmware Version er788

O432

Ground Temperature: 35.3 °C

Test

Test03

Software Version 1.2.4.1

Firmware Version er788

O432

Ground Temperature: 53.6 °C

[Star Strider]

I’ve shared everything II have. If you can post (upload) another of your .txt files, we can troubleshoot this with both of them. That should be enough to test everything.

As I illustrated, ‘Results’ should have all of them.

[James]

Matlab is not allowing me to upload more files.

The data in the Test files look like this:

Test
Test02
Software Version 1.2.4.1
Firmware Version er788
O432
Ground Temperature:	35.3 °C

If you could just copy and paste these two into two seperate text files labeled Test02.txt and Test03.txt. You can then run your code on these three files and see that it does not output Results.

Test
Test03
Software Version 1.2.4.1
Firmware Version er788
O432
Ground Temperature:	53.6 °C

[Voss]

k is being used as both inner and outer loop iterator. Fix that, and it should work:

files = dir('*.txt');

for n = 1:numel(files)
    txt = fileread(files(n).name);
    temppos = strfind(txt,'Ground Temperature:');
    endpos = strfind(txt, '°C');

    for k = 1:numel(temppos)
        section{k,:} = txt(temppos(k):endpos(k));
    end

    for k = 1:numel(section)
        temp(k,:) = sscanf(section{k}, 'Ground Temperature: %f');
    end

    Results{n} = table(temp, 'VariableNames',{'Temp'});
end

Results{:}

ans = table
    Temp
    ____

    29.3

ans = table
    Temp
    ____

    35.3

ans = table
    Temp
    ____

    53.6

[James]

Oh great. Thank you for catching that. It works great!

[Star Strider]

I always use ‘k’ for a loop counter. I should have set the outer loop as ‘k1’, as I usually do in such situations.

[James]

Ok. Is there a way to get all the Results in one table instead of a cell?

[Star Strider]

Yes.

First give each table variable a different variable name:

Results{k1} = table(temp, 'VariableNames',{sprintf('Temp_%d',k1)});

(I just aded numbers here, other options are possible), then concatenate them horizontally:

AllResults = horzcat(Results{:})

That should produce a single table array with all the individual tables (actually table variables) as variables in the concatenated table. They have to have different variable names, or the concatenation step will throw an error.

[James]

Thank you!

[Star Strider]

As always, my pleasure!