MATLAB: Is there a way to plot multiple files using a loop in matlab

excelforfor loopindexindexingMATLABplotplottingstringstrings

I want to use a for loop to plot data from a range of files whos names are string values. This is the code I am using:

 %Convert variable year from integer to string
yr=num2str(17);
dy=num2str(15);
mn=num2str(3);
 yr2 = num2str(17);
dy2 = num2str(4);
mn2 = num2str(4);
 %Create a MMDDYY string 
date_str=[mn '-' dy '-' yr];
date_str2=[mn2 '-' dy2 '-' yr2];
 for i = date_str:date_str2

is there a way I can plot the data from 3-15-17 to 4-4-17, which are in excel files? I already have programs in which I can plot an individual day, I just want to be able to plot a range of days.

Best Answer

Instead of manually creating date strings, try using the datetime object. It can be iterated like you want, and then you can create a string representing the filename using the datestr function.

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MATLAB: How to convert string to date

Date = '10:12:25 Tue 11-Dec-18'
res = datetime(Date ,'InputFormat','HH:mm:ss eee dd-MMM-yy','Format','dd/MM/yyyy HH:mm a')
Date =
    '10:12:25 Tue 11-Dec-18'
res = 
  datetime
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MATLAB: I am creating a date file using the following script, i want it to print DATES[] in the file the_dates.txt but it’s only printing one date which is 2.0171e+09, that is when i type A(1,1)…i pleading for help

The problem with your file is that you overwrite your Date_num value whenever you calculate a new one. Your DATA variable has no function inside the loop, After the loops, DATA will only replicate Date_num, and is thus superfluous.

Your approach is fine as a Matlab exercise, but for serious work I recommend that you type 'doc datetime' and learn about this and other built-in time and date functions.

Here is version of your code that will work and hopefully do what you want:

Date_num = [];
for iy = 2005:2017
        yr = num2str(iy);
  for im = 1:12
    if im < 10
       mn = sprintf('0%s',num2str(im));
    else
       mn = num2str(im);
    end
    switch im
      case {1 3 5 7 8 10 12}
         M_END = 31;
      case {4 6 9 11}
         M_END = 30;
      otherwise
         %----------------------------------------------------------

         % Check whether this is a leap year or not and then assign
         % the appropriate month end.
         %----------------------------------------------------------
         ny = str2num(yr);
         ly = isequal(floor(ny/4)*4,ny);
         if ly == 1
            M_END = 29;
         else
            M_END = 28;
        end
    end
    for id = 1:M_END
      if id < 10
         dy = sprintf('0%s',num2str(id));
      else
         dy = num2str(id);
      end
      dt = strcat(yr,mn,dy); ndt = str2num(dt);
        for ih = 0:6:18
          if ih < 10
             hr = sprintf('0%s',num2str(ih));
          else
             hr = num2str(ih);
          end
  %         DATES=[];
          Date_STR= strcat(dt,hr);
          Date_num= [Date_num;str2num(Date_STR(end,:))];
        end
      end
    end
  end
  % DATES=vertcat(DATES,[Date_num]);
  fn=sprintf('my_dates.txt');
  fid=fopen(fn,'w');
  fprintf(fid,'%10.2f\n',Date_num);
  fclose(fid);

Best Answer

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MATLAB: How to convert string to date

MATLAB: I am creating a date file using the following script, i want it to print DATES[] in the file the_dates.txt but it’s only printing one date which is 2.0171e+09, that is when i type A(1,1)…i pleading for help

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