Stretching a rectangle over a date axis

Hello, I have a graph with dates as X axis (datetime variables) I'm trying to stretch a rectangle over certain dates (I have the dates stored in a vector), but the problem is that the X axis is datetime and the Y axis is doubles, so MATLAB throws an error. How can I fix this?

for I = 1:1:length(main_idleDateMat(:,1))
    startX = main_idleDateMat(I,1);
    endX = main_idleDateMat(I,2);

    rectangle('Position', [startX idleVecStartHeights(I)-80 (endX - startX) 160]);
  end

Answer 1

[dpb]

Ayup, "no can do" it seems...another place TMW either hasn't yet got a round tuit or didn't think it needed to add an overloaded plotting function to take care of the new class object.

All is not lost, however, but it's a regression, indeed. :(

You'll have to revert to the venerable datenum form to plot to subsequently use rectangle or draw the lines directly with plot or line. If you do the former, then will have to also use datetick to format the x-axis as date. All in all, the direct-drawing option may turn out "more better".

ADDENDUM

Use patch. You'll have to provide X,Y vectors to outline the four corners, but it an aliased version has been created that is datetime-aware so TMW has, to their credit, done the most fundamental routine.

Mayhaps they'll eventually get to the rest...

[dpb]

[Answer moved to Comment -- dpb]

Thank you! Using plot worked!

[dpb]

Yeah, the overloaded plot functions know what to do with the datetime or timeseries axes; it's still a work in progress for some of the other specialty routines.

Not clear whether they "just haven't got there yet" or nobody's really thought about such and have simply overlooked the other functions. Probably worth enhancement request/feature shortage/quality of implementation/bug report depending on one's point of view of how to judge the failure.

[Avi Michaely]

Do you know if I can fill the rectangle somehow?

Answer 2

[Ian]

There's a nice solution to drawing a semi-transparent colored rectangle over a plot at https://stackoverflow.com/questions/45266078/how-to-draw-a-colored-rectangle-on-a-plot-when-x-axis-is-time

Alternately, you can use area(...) ,setting 'basevalue' to define the bottom of the rectangle:

area([dates(1),dates(2)],[.4,.4],'facecolor',[.8,1,.8], ...
    'facealpha',.5,'edgecolor','none', 'basevalue',-.2);

will draw a rectangle with x values between dates(1) and dates(2), and y values between -.2 (basevalue) and .4 .

[F S]

awewome, thanks!

Answer 3

[Stephen23]

"How can I fix this?"

Use RULER2NUM, which converts from the ruler values (e.g. DATETIME) to numeric, correctly accounting for the ruler starting value:

https://www.mathworks.com/help/matlab/ref/ruler2num.html

ax = axes();
t = datetime(2015,1,1:10);
y = [0.2,0.3,0.5,0.2,0.8,0.2,0.3,0.1,0.3,0.4];
plot(ax, t,y,'-o')

x = ruler2num(t,ax.XAxis);
rectangle(ax, 'Position',[x(4),y(4),diff(x(4:5)),diff(y(4:5))], 'Curvature',[0.5,0.6])

Do not use DATENUM or other deprecated functions:

Answer 4

[Laurent]

In case somebody still wants to use rectangle, it seems rectangle considers the origin as the low axis limit and the width in number of days (as datetime goes). Thus you have to work with your (rectangle) coordinates as difference from the low time axis limit. I tried plotting a month of data with the time being on x-axis and this works (at least for me):

% Defines dummy time series and plots
time = datetime( [2025 5 3] ) : 1/24 : datetime( [2025 5 28] );
data = rand( size( time ) );
plot( time, data, '.' ); XLim = xlim;
% Draws rectangle from May 15 to May 20 and 0.1 to 0.9
TimPos = datenum( diff( [ XLim(1) datetime( [2025 5 15; 2025 5 20] )' ] ) );
rectangle( 'Position', [ TimPos(1) 0.1 TimPos(2) 0.8 ] )

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Be carefull: if you resize using zoom and want to redraw a rectangle, it is the original axis size that works (do not redo an xlim after zooming to determine the new TimPos).