How to use duration data in the x axis of a patch graph?

I have to realize a "timeline" patch graph. Even though the vectors X and Y that I use in the patch function have the same dimensions, it says that "vectors must be the same length". I think it's because in my case I use for X, duration type data.

Any suggestions on how to handle duration data in a patch graph?

Answer 1

[Star Strider]

Post the code and post the MATLAB version you are using. Only in the last 2 releases (that I am aware of) has patch supported datetime or duration arrays.

If I remember correctly, fill always has, so that may be a work-around.

.

[Pietro Fedrizzi]

Rather than download it and import eh .mat file, I just experimented with it here.

%matlab version R2021b
load('M.mat')
t1 = M{1,1}.Var1;
t2 = M{2,1}.Var1;
t3 = M{3,1}.Var1;
dv1 = datevec(t1);
dv2 = datevec(t2);
dv3 = datevec(t3);
GiornoMeseAnno1 = datetime(dv1(:,1:3));
GiornoMeseAnno2 = datetime(dv2(:,1:3));
GiornoMeseAnno3 = datetime(dv3(:,1:3));
OreMinutiSecondi1 = duration(dv1(:,4:end));
OreMinutiSecondi2 = duration(dv2(:,4:end));
OreMinutiSecondi3 = duration(dv3(:,4:end));
OMS1 = (OreMinutiSecondi1)';
OMS2 = (OreMinutiSecondi2)';
OMS3 = (OreMinutiSecondi3)';

x1 = [OMS1;OMS1;OMS1;OMS1;];
x2 = [OMS2;OMS2;OMS2;OMS2;];
x3 = [OMS3;OMS3;OMS3;OMS3;];


y1 = [(M{1,1}.Var2)';(M{1,1}.Var2)';(M{1,1}.Var2+1)';(M{1,1}.Var2+1)']; 
y2 = [((M{2,1}.Var2)+1)';((M{2,1}.Var2)+1)';(M{2,1}.Var2+2)';(M{2,1}.Var2+2)'];
y3 = [((M{3,1}.Var2)+2)';((M{3,1}.Var2)+2)';(M{3,1}.Var2+3)';(M{3,1}.Var2+3)'];

% x1y1_lims = [min(y1,[],2) max(y1,[],2)];
c = jet(size(x1,1));

figure()
hold on
for k = 1:size(x1,1)
    patch(x1(k,:),y1(k,:),c(k,:));
end
hold off

I have no idea what you’re doing. The code simply plots horizontal lines, and the only way to do that is with a loop in this instance.

This is the best I can do with this.

[Pietro Fedrizzi]

It's basically what I have to do... 'M' is a cell array where in the first column there are 3 tables which contain the time and the position of the various tags during a specific datetime. Basically I have to plot 3 horizontal lines, one for each tag, filled when the position of the tag is a number and empty where is NaN.

[Pietro Fedrizzi]

So my idea was to create the 4xn vectors y1,y2,y3 which should give me the y coordinates of the lines (rectangles) that I want to fill, and I think that those are ok, but I cannot understand how to handle the duration data. (I have an examble about the use of patch wher both X & Y vectors where simple numeric matrices.)

[Star Strider]

If any data are NaN in a patch argument, the entire area will not plot as a patch. Since the objective is to draw wide, filled horizontal lines of different colours, there are easier ways to do that.

I would do something like this instead —

x = 1:10;
y = [1 1 1 NaN 1 NaN 1 1 NaN 1];

figure
plot(x, y, 's-g', 'LineWidth',7, 'MarkerSize',1)
grid

In the online Run feature, the squares are plotting as ‘+’ for some reason. They plot correctly when I use this offline on my computer.

.

[Pietro Fedrizzi]

I didn't know that, thanks! I agree that is way simplier to accomplish this task in the way you showed me, however if there is any way I'd like to do it by filling a rectangle just for an aesthetic purpose, not only a line.

So, is there a way to replace those NaN elements with 0 for example so that I'm able to define the region I want to fill?

[Pietro Fedrizzi]

Never mind, I have changed the NaN values with 0 but the same error remains...

Even though the duration vector and the y vector have the same length, it keeps saying that the have different length according to patch... So I'm back dealing with the duration...

[Pietro Fedrizzi]

Never mind again! Just found out the mistake... It was in defining C in patch(X,Y,C)!

This is the result, which is pretty much what I desired..

load('M.mat');
t1 = M{1,1}.Var1;
t2 = M{2,1}.Var1;
t3 = M{3,1}.Var1;
dv1 = datevec(t1);
dv2 = datevec(t2);
dv3 = datevec(t3);
GiornoMeseAnno1 = datetime(dv1(:,1:3));
GiornoMeseAnno2 = datetime(dv2(:,1:3));
GiornoMeseAnno3 = datetime(dv3(:,1:3));
OreMinutiSecondi1 = duration(dv1(:,4:end));
OreMinutiSecondi2 = duration(dv2(:,4:end));
OreMinutiSecondi3 = duration(dv3(:,4:end)); 

OMS1 = (OreMinutiSecondi1)';
OMS2 = (OreMinutiSecondi2)';
OMS3 = (OreMinutiSecondi3)'; 

tempo1 = [[OMS1(2:end),OMS1(1)];OMS1;OMS1;[OMS1(2:end),OMS1(1)];];
tempo2 = [[OMS2(2:end),OMS2(1)];OMS2;OMS2;[OMS2(2:end),OMS2(1)];];
tempo3 = [[OMS3(2:end),OMS3(1)];OMS3;OMS3;[OMS3(2:end),OMS3(1)];];

y1 = [(M{1,1}.Var2)';(M{1,1}.Var2)';(M{1,1}.Var2+1)';(M{1,1}.Var2+1)']; 
y2 = [((M{2,1}.Var2)+1)';((M{2,1}.Var2)+1)';(M{2,1}.Var2+2)';(M{2,1}.Var2+2)'];
y3 = [((M{3,1}.Var2)+2)';((M{3,1}.Var2)+2)';(M{3,1}.Var2+3)';(M{3,1}.Var2+3)'];

y1(isnan(y1)) = 0;
y2(isnan(y2)) = 0; 
y3(isnan(y3)) = 0;

figure()
patch(tempo1,y1,'blue');
hold on
patch(tempo2,y2,'red');
hold on
patch(tempo3,y3,'green');
hold off

Now I only have to adjust it...

Sorry to disturb you!

[Star Strider]

The problem with the ‘length’ error is that the arguments to patch are matrices with more than two rows or columns. The patch function can (to the best of my knowledge), only use two rows or columns for ‘x’, ‘y’ (and ‘z’) so the loop works while the original code does not.

I am not certain what the condition that throws that error is actually looking for, so the error text itself may be misleading.

Drawing a long, thin box is straightforward —

x = 0:10;
y = ones(size(x))*0.5;
boxHeight = 0.005;                              % Half Box Height

figure
patch([x, flip(x)], [y-boxHeight flip(y)+boxHeight], 'g', 'EdgeColor','none')
grid
ylim([0 1])

It would work with a duration or datetime array (at least in R2021a and after), however I did not use those here out of simplicity.

.

[Pietro Fedrizzi]

Got it!

Thanks again Sir for you time and your help!

[Star Strider]

As always, my pleasure!

.