How to plot a broken horizontal line (ie, a horizontal line with whitespace)

As above, I am trying to plot segments of a horizontal line, y = 5. I have a vector called v of ones and zeros, the ones representing the line I want to plot, and zeros indicating whitespace. I've had trouble finding a formal way to put this, so I've included a picture illustrating what I mean.

[Geoff Hayes]

Daniel - how do you map the dashes to the x-axis? For example, if you have

 0 0 0 1 1 1 0 0 0 1 1 1

what is the equivalent x-value for each of the above? Is it

 1 2 3 4 5 6 7 8 9 10 11 12

or

 0.5 1 1.5 2 2.5 ...

[Daniel Pollak]

Hi Geoff, it's the first:

1 2 3 4 5 6 7 8 9 10 11 12

Answer 1

[Geoff Hayes]

Daniel - so if your array of zeros and ones is

 onOffData = logical([0 0 0 1 1 1 0 0 0 1 1 1]);

and it maps to 1, 2, 3, ... then you could do something like

 xData = 1:1:length(onOffData);
 yData = zeros(size(xData));
 yData(onOffData) = 5;

You can then plot the data as

 plot(xData,yData,'.')

and you should see the '.' wherever there is a one in your logical array. (Note the conversion to the logical array above so that we can easily set the on (1) elements to 5 in the yData(onOffData) = 5; assignment).

Answer 2

[Stephen23]

NaN values are not plotted, so all you need is to plot a vector with NaNs in the location that you do not want plotted:

V = [0,0,0,1,1,1,0,0,0,1,1,1];
V(V==0) = NaN
plot(V)

[Daniel Pollak]

This seems to work for small arrays. With my large dataset of doubles and NaNs, just

plot(V)

works instantaneously ,but freezes my computer if I do

plot(V, 5)

My data are 10,078,080 data points long, and MATLAB has no problem with vectors sans NaNs, or plotting them as above, but because this vector has NaNs and it is long, it takes an enormous amount of time. What can be done?

[Stephen23]

10,078,080 is not a trivially small number of points to plot, so perhaps one workaround would be to reduce the number of points plotted. This can be done quite simply by only plotting the start and end points of each line segment. Here is one way to do this:

V = [0,0,0,1,1,1,0,0,0,1,1,1];
X = reshape(find(diff([0,V,0])),2,[]);
X(2,:) = X(2,:)-1;
Y = [5;5];
plot(X,Y)

I have no idea how fast/slow this is in comparison to using NaN, so please try it and let me know!

[Daniel Pollak]

You know, this took a long time too. However, diff([0,V,0]) really helped me out with another problem! So thanks for that. Also, I'm going to add some sample data to my question.