X, Y plot with errorbars on the same figure ?

I would like to plot errorbars on a X,Y plot. Errorbars should be computed based on mean and standard deviation for X data (X data first must be grouped in bins in order mean and standard deviation be computed). I have tried many command but it is no use.

Could you please help me?

Answer 1

[ag]

Hi Ivan,

I understand that you want to plot error bars along with the original plot.

The below code plots X, Y data along with errorbars, where Standard deviation of Y is used as the error lenght.

function [meanv, stdv, xv, nv] = xbinavg(x, y, xedge)
% Averaging y-data with x-data bin
%   # Input
%    x: xdata
%    y: ydata corresponding to x
%    xedge: bin-edges
%  
%   # Output
%    meanv: mean y-value in each x-bin
%    stdv : standard deviation of y  
%    xv   : center values of bin-edges for plot
%    nv   : the number of data in each x-bin
    x = x(:);
    y = y(:);

    for i = 1:length(xedge)-1
	    doil = (x>=xedge(i));
	    doiu = (x<xedge(i+1));
	    
	    % output
	    xv(i)     = mean([xedge(i) xedge(i+1)]);
	    stdv(i) = std(y(find(doil.*doiu)));
	    nv(i) = length(y(find(doil.*doiu)));
	    
		meanv(i) = mean(y(find(doil.*doiu)));

    end
end

%creating random X and Y data
x = rand(1,200)*100;
y = x.^2 + 5000*randn(size(x));


[yMean, yStdDeviation, xBinCenter, binSize] = xbinavg(x, y, 0:10:100);
plot(x,y);
hold on;
errorbar(xBinCenter, yMean,yStdDeviation,'k','LineWidth', 1.5);
hold off;

For more details, please refer to the following pages:

• File exchange page: https://www.mathworks.com/matlabcentral/fileexchange/55222-xbinavg-x-y-xedge-medopt?s_tid=answers_rc2-1_p4_Topic
• errorbar: https://www.mathworks.com/help/matlab/ref/errorbar.html

Hope this helps!