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MampsRex
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How do I plot with error bars in both directions

Asked by MampsRex
on 11 Jan 2016
Latest activity Answered by Christopher Thissen on 1 Feb 2016
Okay, I have two variables, time and temperature. both are 1x10 vector. I also have the error in time and the error in temperature. my time will go on the x axis and the temperature on the y axis. I need to put error bars for the time and temperature points once i have ploted them. I need to do this for various files. So I have recorded them on a text file and done a loop. The errors in the time and temp are also recorded in the txt files. for example in each text file i have the following variables:- row1=time =.......... row2=temp=................. row3=error in time=........... row4=error in temp=.............
I have started like this:-
%Define the file structure
nFiles=500;
filenamePrefix='v';
filenameExtension = '.txt';
for i=1:nFiles
filename= [filenamePrefix, int2str(i), filenameExtension];
tmptimeData=load(filename,'-ascii');
time{i}=tmptimeData(1,:);
temp{i}=tmptimeData(2,:);
figure(i)
plot(time{i}, temp{i}, 'ro')
grid on
hold on
xlabel('temp')
ylabel('time')
end
clear tmptimeData;
So How would I add the error bars on each of the points which are in the same txt files?

  1 Comment

Hi MampsRex,
Let me make sure I understand you correctly, you have the time(x) and temperature(y) data along with error in a file.
For error bars, you may use the "errorbar" function. For instance, if you assume time data as "x" and temperature data as "y", you can do this:
x = 1:10;
y = x.*2;
e = std(y)/10*ones(size(x)); % assuming e as error
plot(x,y,'ro')
hold on
errorbar(x,y,e)
Thank you,
Adithya

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1 Answer

Answer by Christopher Thissen on 1 Feb 2016

Hi Mamps,
You can use my errorbarxy function to plot error bars in x and y (time and temperature in your case). For your specific example, your code might look like this:
nFiles=500;
filenamePrefix='v';
filenameExtension = '.txt';
for i=1:nFiles
filename= [filenamePrefix, int2str(i), filenameExtension];
tmptimeData=load(filename,'-ascii');
time{i}=tmptimeData(1,:);
temp{i}=tmptimeData(2,:);
dtime{i}=tmptimeData(3,:);
dtemp{i}=tmptimeData(4,:);
figure(i)
plot(time{i}, temp{i}, 'ro')
errorbarxy(time{i},temp{i},dtime{i},dtemp{i})
grid on
hold on
xlabel('temp')
ylabel('time')
end
clear tmptimeData;
Let me know if you need more explanation. - Chris

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