How can i generate a graph dynamic

Hello community, I'm trying to generate a graph of the ECG trace on GUI, but it shall retain the data for 24h.how can I make a dynamic chart. Wherein the x-axis, can allot time from the start of acquisition to the end. And on the y axis can generate the voltage?

[Joseph Cheng]

One of the initial things that would help is how are you getting the ECG data? is it going to come in real time with other parallel processes that needs to be done?

Answer 1

[Biza Ferreira]

First of all, thanks for replying Joseph Cheng, ECG data are obtained through a txt file. These data come in the form of ASCII, and are stored on a memory card in a txt file through this program after the file is opened and the data is read ...

Answer 2

[Joseph Cheng]

So i'm assuming from the screen shot you already have something that pulls in and reads in the data. So here is a quick example:

%%generate sample file.
fid = fopen('sampleECG.txt','w');
dateN = datenum('03-Sep-2014 15:26:10','yyyymmddTHHMMSS');

for ind = 1:2:24*60 %sample every 2 min.  
    data= 2000+5*sin(2*pi*.009*ind);    
    dateN = addtodate(dateN,2,'minute');
    Dvect = datevec(dateN);
    fprintf(fid,'%02.0f %02d %02d %02d %02d %02d %02.0f\r\n',[data Dvect])
end
fclose(fid)

%%read in data
Data = dlmread('sampleECG.txt',' ');
Data = [Data(:,1) datenum(Data(:,2:end))];

%%find section of data you want to plot
%generate this by using edit fields 
PlotRange = [2014 09 03 23 59 20;2014 09 04 15 01 20]; 
%convert the user entries into date numbers.
PlotRange = datenum(PlotRange); 

%find the time in the files between the two ranges
Range = find(Data(:,2)>=PlotRange(1) & Data(:,2)<=PlotRange(2)); 
figure,plot(Data(Range,2),Data(Range,1))
datetick('x',16),axis tight

So the first section I generate some sample data and then i read it in using dlmread() and store it in as data. to actually plot it dynamically would be that you would need to create a few edit boxes such that the user can enter the time window. here i just put it in as an already made array called PlotRange but this can simple be constructed from entries into the GUI. Then with the knowledge of the window of time we can then search the the dates for data we have. then plot.

[Joseph Cheng]

I forgot to mention that the last few sections can be made into a pushbutton callback labeled something like "update graph" or "plot now". which then would use the get() function to obtain the start and stop time for the window and then update the variable Range.

With this you are keeping all data and using Range to figure out what to plot. This is also a good way to update the plot as when you first read in the file Range can be all ones "ones(length(Data),1)" and then updated based on the specified window.

[Joseph Cheng]

so what portion of my answer could you not have grabbed the necessary portions to get what you need?

the portions of the code you could have extracted from my example to do this are:

• Data = dlmread('loaded file path+name chosen by the push button')
• start acquisition is obviously row 1.
• end acquisition is obviously row(end).
• using date/time is shown in my use of datetick()
• plot data using plot() like i did before. if you wanted the full data file i wouldn't call that dynamic it would be more like automatically. dynamic would mean that it would be able to changed based on something else (ie my edit boxes that chose the start and stop time).

or are you struggling with even the concept of how to pull in the file, and create the plot? From the figures i assumed you were able to pull in the file as you had a button, had the file path+name shown, and the start and stop times.

What are you missing that i have not already given you?

[Joseph Cheng]

you should stop entering comments to new "answers" as your replies are not answers. I am not going to code up a full gui but here are some snippits of code that should help you.

%%read in data
Data = dlmread('sampleECG.txt',' ');
Data = [Data(:,1) datenum(Data(:,2:end))];

startAqc = datestr(Data(1,2:end),31);
stopAqc = datestr(Data(end,2:end),31);

%%get and plot all data 
figure,plot(Data(:,2),Data(:,1))
datetick('x',16),axis tight
newLim = get(gca,'XLim'); 
newx = Data(:,2);

ax = axis %current axis limits
axis(axis)
set(gca,'XTick', newx); 
dateticks = datestr(newx,13);
yl = ax(3:4);
t = text(newx,yl(1)*ones(1,length(newx)),dateticks);
set(t,'HorizontalAlignment','right','VerticalAlignment','top', ...
      'Rotation',45);
set(gca,'XtickLabel','')

for i = 1:length(t)
  ext(i,:) = get(t(i),'Extent');
end

LowYPoint = min(ext(:,2));

% Place the axis label at this point
XMidPoint = Xl(1)+abs(diff(Xl))/2;
tl = text(XMidPoint,LowYPoint,'X-Axis Label', ...
          'VerticalAlignment','top', ...
          'HorizontalAlignment','center');

Answer 3

[Biza Ferreira]

Joseph Cheng, thanks for your reply, I think I do not explained myself well, soo when in my interface I release my "Open File" button all data come to interface,graph is automatically generated through the samples contained in txt file. I want to create something like this:

Answer 4

[Biza Ferreira]

Joseph excuse my ignorance, is that you can send me an example, I have walked around it and can not do