Porblem in exporting a txt file

Hi all,

I have a .txt file (attached) that I want to extract in a matrix format. The .txt file contains the values of Chlorine Results (just ignore the Pipe Results) for only two junctions: Junc_ID 1 and Junc_ID 5 (see row 7-column 37 and row 256-column 37 respectively). The file is reduced in size so I'd like to get the results for N Junc_ID.

So lets say I want to extract the values of Chlorine results over time for EPANET column in a matrix format (let's call matrix 1) and then the values of Chlorine results over time for WUDESIM column (matrix 2) for these jucntions, how could I do?

Find attached the figure showing the format of results I'd like to get.

Anyway I tried the readtable function:

T = readtable('extract.txt','ReadVariableNames', true) and

T= readtable('extract.txt','VariableNamingRule','preserve') in MatlabR2018b but it does not working.

I'd appreciate if anyone could help me.

Thanks,

Stefania

[Rik]

Since your file is a not uniform you have two options:

1. hardcode the line numbers and use the skip header option
2. read your file as text and do the data-extraction yourself with tools like textscan and str2double

I personally would go for option 2.

[Rik]

You could use that, but I would suggest reading your file all at once.

If you are using a new release you can use data=cellstr(readlines('extract.txt'));

If you're using R2020a or older you can use my readfile function, which you can get from the FEX (or the AddOn-manager if you are using R2017a or later).

Then you have a cell array of character vectors, allowing you to use normal for-loops.

Answer 1

[Voss]

Here's one way. This will collect the first three columns of each section into a cell array called data, each element of which corresponds to one junction, so that data{i}(:,j) is the jth column of the ith junction in the file, e.g., in this case, data{2}(:,3) is WUDESIM at junction 5 and data{1}(:,1) is Time at junction 1.

fid = fopen('extract.txt','r');
str = char(fread(fid).');
fclose(fid);

idx_s = strfind(str,'ResT_WUDESIM');
idx_e = strfind(str,'*********************************************************************************************');

idx_s = idx_s+16;
idx_e = idx_e(3:end)-5;

data = {};
for i = 1:numel(idx_s)
    temp = str2num(str(idx_s(i):idx_e(i)));
    data{i} = temp(:,1:3);
end

[Stefania Avvedimento]

Thanks Benjamin, it is exactly what I wanted in a short and fast code. Could you just explain me what the following lines refer to?

idx_s = idx_s+16;

idx_e = idx_e(3:end)-5

Thanks a lot,

Stefania

Answer 2

[Cris LaPierre]

Here's how I would load the data using option 1. I'll let you worry about shaping the data to make the table you want.

% branch1
optsH = detectImportOptions("extract.txt",'ReadVariableNames',true);
optsH.DataLines = [8, 8];
optsH.VariableNamesLine = 7;
optsH = setvartype(optsH,1,"string");

B1_info = readtable('extract.txt',optsH)

B1_info = 1×7 table
    Branch_ID    Pipe_ID    Junc_ID    N_segments    Flow_Corr    Disp_Corr    Rw_Corr
    _________    _______    _______    __________    _________    _________    _______

      "B1"          1          1           1             1            1         {'1'} 

optsB = detectImportOptions("extract.txt",'ReadVariableNames',true);
optsB.VariableNamesLine = 11;
optsB.DataLines = [12, 252];
B1_data = readtable('extract.txt',optsB)

B1_data = 241×6 table
    Time      EPANET      WUDESIM    Reyn_WUDESIM    Pecl_WUDESIM    ResT_WUDESIM
    ____    __________    _______    ____________    ____________    ____________

      0              0       0          266.73           4.228          72834    
      1     7.4449e-18       0          264.46          4.2642          73457    
      2     3.4526e-13       0          263.06           4.287          73850    
      3     6.6482e-11       0          262.69           4.293          73954    
      4      2.086e-09       0          261.98          4.3047          74155    
      5     2.0398e-08       0          262.01          4.3041          74145    
      6     9.8362e-08       0          264.35           4.266          73489    
      7     3.2544e-07       0           270.9          4.1628          71711    
      8     9.3243e-07       0          273.69          4.1204          70980    
      9      2.364e-06       0          273.35          4.1256          71070    
     10     4.9397e-06       0          272.98          4.1311          71165    
     11     8.6201e-06       0          272.63          4.1364          71257    
     12     1.3135e-05       0          272.58          4.1372          71269    
     13     1.8303e-05       0           272.8          4.1338          71212    
     14     2.4263e-05       0          273.02          4.1305          71154    
     15     3.1836e-05       0          272.17          4.1435          71378    

% branch2
optsH.VariableNamesLine = 256;
optsH.DataLines = [257,257];

B2_info = readtable('extract.txt',optsH)

B2_info = 1×7 table
    Branch_ID    Pipe_ID    Junc_ID    N_segments    Flow_Corr    Disp_Corr    Rw_Corr
    _________    _______    _______    __________    _________    _________    _______

      "B2"          4          5           1             1            1         {'1'} 

optsB.VariableNamesLine = 260;
optsB.DataLines = [261, 501];
B2_data = readtable('extract.txt',optsB)

B2_data = 241×6 table
    Time      EPANET       WUDESIM      Reyn_WUDESIM    Pecl_WUDESIM    ResT_WUDESIM
    ____    __________    __________    ____________    ____________    ____________

      0              0             0       670.46          1.5641          26944    
      1     5.6972e-16             0       596.61          1.7577          30279    
      2     1.3406e-11             0       554.02          1.8928          32607    
      3     1.6262e-09             0       543.24          1.9304          33253    
      4     3.6212e-08             0       522.72          2.0061          34559    
      5     2.4877e-07             0       523.75          2.0022          34491    
      6     9.1806e-07             0       593.04          1.7683          30461    
      7     2.6721e-06             0       832.07          1.2603          21710    
      8     8.2654e-06             0       974.14          1.0765          18544    
      9     2.0306e-05             0       954.02          1.0992          18935    
     10     3.6134e-05             0        933.7          1.1231          19347    
     11     5.2998e-05             0       914.85          1.1462          19746    
     12     6.8857e-05             0       912.35          1.1494          19800    
     13     8.6268e-05             0          924          1.1349          19550    
     14     0.00010516             0       935.92          1.1204          19302    
     15     0.00014593    0.00011649       891.38          1.1764          20266