write data into a file line by line inside foef(fid) loop

Hi,

I need to read data from .txt file line by line and then for each line I have to call a function (function takes single value each for all inputs at a time and gives the output with dimension 1x3) and save it. Then, it "ll read 2nd line, call function and save it as nextline in file. Same for 3rd lines and so on. The function works fine for 1st line, from 2nd lines it shows error (it is because function takes only a single value each for all inputs). Can anyone help. Thank you so much. My code is below.

clear all;clc;
fid=fopen('testfile.txt','r');
fid1 = fopen('test.txt', 'wt');
i = 0;
while ~feof(fid);
      i;
      %%%get data
      line = fgetl(fid); 
      ms=line(1:10);t=line(12:23);
     alt(i+1)=str2num(line(29:38))*1e-3;%m to km
     lon(i+1)=str2num(line(41:47));
     lat(i+1)=str2num(line(49:55));
     lst(i+1)=str2num(line(57:62));
     dens(i+1)=str2num(line(72:88))*1e-3;%kgm-3 to gcm-3
%%convert to ut 
       ut(i+1)= rem(datenum(t),1)*24; 
      sec(i+1)=ut(i+1)*3600;
%convert to doy 
dt(i+1)=datetime(ms, 'ConvertFrom','datenum');                  
doy(i+1)=day(dt(i+1),'dayofyear');   
%%assume some year, f107a,f107 and ap for testing
year(i+1,:)=2000;
f107a(i+1,:)=150;f107(i+1,:)=150;ap(i+1,:)=4;
%%call function
%%function takes single value of each input paramaters at a time
%%outputn has dimension of 1x3
[outputn]=nrlmsise00_code(doy,year,sec,alt,lat,lon,lst,f107a,f107,ap);
%%normalize data
densn1(i+1)=dens(i+1)*outputn(2)/outputn(1);
densn2(i+1)=dens(i+1)*outputn(3)/outputn(1);
new_data=[densn1 densn2 outputn];
%%save file
fprintf(fid1,'%d %d %d %d %d\n',new_data);  
i = i+1;
end; 
fclose(fid);fclose(fid1);

Answer 1

[KSSV]

I would first read the complete file and then run loop for each line.

T = readtable('https://in.mathworks.com/matlabcentral/answers/uploaded_files/1080015/testfile.txt') 

T = 5×12 table
       Var1         Var2       Var3         Var4        Var5      Var6       Var7      Var8        Var9         Var10       Var11    Var12
    __________    ________    _______    __________    ______    _______    ______    ______    __________    __________    _____    _____

    2002-04-04    00:50:00    {'GPS'}    5.1873e+05    146.08    -56.598    10.516    303.54    1.3136e-12     1.241e-12      0        0  
    2002-04-04    00:50:10    {'GPS'}    5.1864e+05    146.07    -55.967    10.518    304.18    1.3165e-12    1.2409e-12      0        0  
    2002-04-04    00:50:20    {'GPS'}    5.1855e+05    146.06    -55.336     10.52    304.81    1.3144e-12    1.2408e-12      0        0  
    2002-04-04    00:50:30    {'GPS'}    5.1845e+05    146.06    -54.705    10.522    305.44    1.3145e-12    1.2407e-12      0        0  
    2002-04-04    00:50:40    {'GPS'}    5.1835e+05    146.04    -54.074    10.524    306.07    1.3198e-12    1.2406e-12      0        0  

You can access the column you want by using T.(1), T.(2), T.(3) etc.

[Madan Kumar]

Thank you so much. I am using matlab2015a and when I use your method output T is 4x1 table. Then col1=T.(1) gives (4x1 cell). T.(2) gives "index exceeds matrix dimensions",i.e., dimensional error. It seems columns cannot be accessed by T.(1),T.(2) and so on.

[KSSV]

Try xlsread

[Madan Kumar]

isn't it used to read Excel files? Here, I have .txt. I am just using a simple example. Real file is large one.

[KSSV]

Yes... you are right....explore the readtable option...

[Madan Kumar]

Thank you so much. I am exploring readtable option but yet to succeed.