MATLAB: How to plot the lower or upper boundary lines for scatter data

scatter plot boundary lineyongnuan liu

I have a scatter plot. I'd like to plot the lines connecting the points either the upper or lower bound.

How to do it?

Could you please help? Thank you so much.

Best Answer

You could use boundary() to help figure out which points are on the perimeter. Figuring out which of those points are on the upper or lower branch might take some thinking for irregular point distributions.

Related Solutions

MATLAB: How to plot a box on an existing plot

xmin=0;
xmax=1;
ymin=0;
ymax=1;
plot([xmin xmax xmax xmin xmin],[ymin ymin ymax ymax ymin])

rectangle('position',[xmin ymin xmin xmax])

MATLAB: How to display trendline equation on the plot

ok, I got it now.

here are my codes,

fittedlinecrossplot=polyfit(xdata_crossplot,ydata_crossplot,trendlinepolynomialcoeff); ydata_crossplot_trendline=polyval(fittedlinecrossplot,xdata_crossplot_trendline);

            trendlineequationcoeffnum=length(fittedlinecrossplot);
            switch trendlineequationcoeffnum
                case 2  % means it has slope and intercep 2 numbers
                     trendlineequationstring=sprintf('y=%.3f x+%.3f',fittedlinecrossplot(1),fittedlinecrossplot(2));
                case 3
                     trendlineequationstring=sprintf('y=%.3f x^2+%.3f x+%.3f',fittedlinecrossplot(1),fittedlinecrossplot(2),fittedlinecrossplot(3));
                case 4
                    trendlineequationstring=sprintf('y=%.3f x^3+%.3f x^2+ %.3f x+%.3f',fittedlinecrossplot(1),fittedlinecrossplot(2),fittedlinecrossplot(3),fittedlinecrossplot(4));
                case 5
                    trendlineequationstring=sprintf('y=%.3f x^4+%.3f x^3+ %.3f x^2+%.3f x+%.3f',fittedlinecrossplot(1),fittedlinecrossplot(2),fittedlinecrossplot(3),fittedlinecrossplot(4),fittedlinecrossplot(5));
            end
            htrendlinetext=text(pos_rightsubplot(1)+0.5*pos_rightsubplot(3),pos_rightsubplot(2)+0.8*pos_rightsubplot(4),trendlineequationstring,'units','normalized');
            htrendlinetext.FontSize=12;
            htrendlinetext.FontWeight='bold';
            htrendlinetext.Color='r';

Best Answer

Related Solutions

MATLAB: How to plot a box on an existing plot

MATLAB: How to display trendline equation on the plot

Related Question