Parsing .txt File with Unique Format

Hi,

I am struggling to parse a .txt document. A sample format of the .txt document is attached. Essentially, I need to extract the first column, L, as well as the third to last column, MCA, into separate tables in MATLAB, one table for each sample. There are several thousands of lines of data, all in the aforementioned format. The sample text file attached has four samples (#S 1, #S 2, etc.).

I have a feeling my current approach is not efficient. I used the pound symbol as the delimiter, and got everything loaded into a cell with the following code. I even was able to ascertain the lines in which the "headers" were found. There must be a more straightforward way.

filename='sample.txt';

fid =fopen(filename);

c=textscan(fid,'%s','delimiter','#');

index=find(contains(c{1,1},'L X Scan H K L V Epoch Monitor Voltage Ion 2 Trans Ni Cu MCA Seconds Detector'));

fclose(fid);

I am a novice in MATLAB, and would really appreciate any help regarding this.

Answer 1

[Star Strider]

This will read it successfully —

fidi = fopen('sample.txt','rt');

k1 = 1;

while ~feof(fidi)

C = textscan(fidi, repmat('%f',1,15), 'HeaderLines',31, 'CollectOutput',true);

M = cell2mat(C);

if isempty(M) % Empty Matrix Indicates End-Of-File

break

end

D{k1,:} = M;

fseek(fidi, 0, 0);

k1 = k1 + 1

end

fclose(fidi);

Out = cell2mat(D);

OutTable = array2table(Out);

For the posted file, it produces a (132x15) double array that you can then use to create a table with the array2table function (as I have done here), and create one or more derivative table arrays with the information you want to work with.

The first five rows of ‘OutTable’ are:

Out1      Out2       Out3          Out4        Out5     Out6    Out7    Out8    Out9     Out10    Out11    Out12    Out13    Out14    Out15
______    ______    _________    __________    ______    ____    ____    ____    _____    _____    _____    _____    _____    _____    _____

2.7609    1.1335    -0.030778    -0.0090013    -5e-05    190     3001     0      45528      0        3       10       249     0.267    5755 
2.7641    1.1335    -0.030778    -0.0090013    -5e-05    192     3001     0      45343      0        2        9       206     0.266    5732 
2.7673    1.1335    -0.030778    -0.0090013    -5e-05    194     3001     0      46540      0        2        6       228     0.273    5549 
2.7705    1.1335    -0.030778    -0.0090013    -5e-05    196     3001     0      45609      0        3        6       223     0.268    5948 
2.7737    1.1335    -0.030778    -0.0090013    -5e-05    197     3001     0      44275      0        1       10       224      0.26    5734 

.

.

[Nigel Caprotti]

Thank you for this correspodence -- answered my question.

[Star Strider]

As always, my pleasure!

Answer 2

[Walter Roberson]

Cases like this are often most easily processed by reading the entire file as text and then using regexp() to extract information.

You might, however, be able to use textscan in a loop, making use of the CommentStyle option to skip the headers, and probably using a format repeat count of 1.

[Nigel Caprotti]

Appreciate this.