Cannot overlay line of best fit over boxplot

In the script below;

% Fit line of best fit to median data

logData=log(Data+1); y=median(logData); x=j; [P,S]=polyfit(x,y,1); [Y,DELTA]=polyval(P,x,S);

% Plot everything

ii=ii+1; figure(ii) orient Landscape; set(gcf,'units', 'normalized', 'outerposition', [0 0 1 1]);

%boxplot(logData, num2cell(int16(j))) boxplot(logData, int16(j)), hold on

plot(x,Y, 'c','LineWidth', 3) plot(x,Y+DELTA,'r-') plot(x,Y-DELTA,'r-') title('log(BEFORE Data + 1)') hold off boxplot plots correctly and the line of best fit, if plotted on a separate figure also plots correctly. However the line of best fit is NOT overlaid on the boxplot as intended. I think that I am using hold on and hold off correctly? Why is this not working?

Answer 1

[Star Strider]

I can’t run your code (and I don’t have the energy just now to try to re-create your data), so it may be that all the ‘hold on’ commands could be the problem. Just one call to each should suffice.

Try this instead:

figure(ii)
orient Landscape;
set(gcf,'units', 'normalized', 'outerposition', [0 0 1 1]);

boxplot(logData, int16(j))
hold on
plot(x,Y, 'c','LineWidth', 3)
plot(x,Y+DELTA,'r-')
plot(x,Y-DELTA,'r-')
title('log(BEFORE Data + 1)')
hold off

[BGC]

Hi Star Strider, thanks for the suggestion, however removing a couple of superfluous hold on has had no effect. Note that I can easily plot the boxplot and the lines of best fit on separate graphs! They just wont overlay and I have no idea why!! It is such a trivial problem, but I would appreciate another solution! BGC

[Star Strider]

I don’t have your data, so I can’t test your code. The only other thing I can think of is to be sure that ‘Y’ and the others actually appear on the same x- and y-scales of your boxplot. The easiest way to do this is to plot them separately (as you have done), then look at the axis scales and limits on each plot. They could be plotting fine, and you can’t see them because they’re off the axes. (This is most likely the problem when you’ve restricted the axis limits with the axis function.)

[BGC]

Hi Star Strider, I have found the solution! I modified the boxplot command to "link" the positions of the boxes with the x axis of the line of best fit. The modified boxplot command is now; boxplot(logData, int16(j),'positions',x) ..and that works! Thanks for your help. BGC

[Star Strider]

My pleasure.

Answer 2

[Helen Kourous]

"Hold on" does not seem to work well with boxplots, even when you presize the axes. (Even tried "hold all")