Import data as a structure array from a text file with different titles in the middle.

Hi,

I have this kind of a data file (I have attached the file here), for different time values particle cordinates and other variables. I want to import this data to matlab as structure array, Ex: for differenent time values x, y, z columns. Attached file has x, y, z,...data for 2 time values. My original file has this for 2796 time values (huge file).

So far I have tried this but it didn't work. And I can't understand how to use "struct" here, 1*2796 struct with 4 fields (number of particles (50), x, y, z) . My ultimate goal is to make a movie with these particle trajectoties.

pardist = load('datafile.txt');

for t=-3.555e-11:2e-11:5.590e-8  %this is the time frame.
    for k=0:2796                 % how many times 
     k1=3+3*k+50*k;              % to get the correct row number; as I have time and column name in the middle.
   data(t)=pardist(:,k1:k1+49)
    end
end

Could you please help me with importing this data to a structure array. Thank you very much.

[Stephen23]

You should read these:

https://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

Answer 1

[Stephen23]

opt = {'MultipleDelimsAsOne',true};
out = {};
[fid,msg] = fopen('datafile.txt','rt');
assert(fid>=3,msg)
while ~feof(fid)
    str = fgets(fid);
    val = sscanf(str,'time%f');
    if numel(val)
        hdr = regexp(fgets(fid),'\w+','match');
        fmt = repmat('%f',1,numel(hdr));
        tmp = textscan(fid,fmt,opt{:});
        tmp = cell2struct(tmp,hdr,2);
        tmp.time = val;
        out{end+1} = tmp;
    end
end
fclose(fid);
out = [out{:}]; % All structures must have the same fields!

Checking the output structure:

>> out
out =
  1x2 struct array containing the fields:
    x
    y
    z
    rxy
    G
    Bx
    By
    Bz
    m
    q
    nmacro
    rmacro
    ID
    fEx
    fEy
    fEz
    fBx
    fBy
    fBz
    time
>> out(1).time
ans = -0.000000000035550
>> out(1).x
ans =
  -0.000671100000
   0.000557200000
  -0.000973600000
   0.000186800000
   0.000594100000
   0.000012390000
   0.001282000000
  -0.000289500000
  -0.001298000000
   0.000587800000
  -0.002283000000
   0.000353100000
   0.001420000000
  -0.000765300000
   0.000874900000
  -0.000914000000
   0.000142200000
  -0.000250900000
   0.000243000000
   0.001025000000
  -0.000179200000
   0.002040000000
  -0.000258000000
  -0.001343000000
   0.000287200000
  -0.001529000000
   0.000887600000
   0.002393000000
  -0.000354500000
   0.000134900000
  -0.000845700000
  -0.000897900000
   0.000972200000
  -0.000000027500
   0.000247200000
  -0.000262000000
   0.001278000000
  -0.000545300000
  -0.002156000000
   0.000313400000
  -0.001397000000
   0.000723800000
   0.001591000000
  -0.000895500000
   0.000795900000
  -0.000517700000
  -0.000153600000
   0.000869200000
  -0.000573800000
   0.000658400000
>> out(2).G
ans =
   1.1620
   1.1350
   1.1280
   1.1170
   1.1120
   1.1050
   1.1010
   1.0950
   1.0930
   1.0880
   1.0860
   1.0820
   1.0790
   1.0760
   1.0740
   1.0710
   1.0660
   1.0650
   1.0620
   1.0600
   1.0580
   1.0570
   1.0540
   1.0530
   1.0510
   1.0490
   1.0470
   1.0460
   1.0440
   1.0420
   1.0400
   1.0390
   1.0370
   1.0340
   1.0330
   1.0300
   1.0290
   1.0270
   1.0260
   1.0240
   1.0230
   1.0210
   1.0190
   1.0170
   1.0160
   1.0130
   1.0120
   1.0090
   1.0080
   1.0040

[S]

Thank you so much.