Is it possible to connect points on a scatter plot with arrows instead of a line?

Hello,

I am looking to show how oxygen and carbon covary over time in a simple x-y scatterplot. However, instead of the points being connected by lines, I'd like them to be connected by arrows. Is it possible to do this on MatLab or would I need to export the figure and insert the arrows using Adobe?

Here is an example of a plot code:

% Inflata

figure('Color','w');

plot(c13xi87,o18xi87);

ylabel('G. Inflata \delta^1^8O');

set(gca,'YDir','reverse');

xlabel('G. Inflata \delta^1^3C');

[Walter Roberson]

I am confused. You are not using a scatter plot: scatter plots have no ordering between the points.

[Vince Clementi]

Not entirely true. I am looking at the covarying of oxygen and carbon isotopes through time. Think of three columns: column one is Age (in thousands of years before present). For each age, there is an oxygen and carbon isotope (columns two and three, respectively). I am plotting column 2 v. column 1, but the position of the points in the scatter plot is also a function of age. Therefore, connecting the points in order will show how they shift with time.

[José-Luis]

I think you are confused about nomenclature. In Matlab terms, a scatter plot has no ordering. Please read the documentation.

[Vince Clementi]

We refer to X-Y plots as scatter plots, which this is. I am connecting the points in a way that shows a third dimension.

[Walter Roberson]

http://stattrek.com/statistics/dictionary.aspx?definition=Scatterplot

"A scatterplot consists of an X axis (the horizontal axis), a Y axis (the vertical axis), and a series of dots. Each dot on the scatterplot represents one observation from a data set. The position of the dot on the scatterplot represents its X and Y values."

Notice the reference to "dots". If you are connecting anything, you do not have a scatter plot. You might have a time series plot, or a series of time series plots.

Answer 1

[aborghes]

Hi Vince, I would recommend using the quiver() function. The doc for it is located here: https://mathworks.com/help/releases/R2017a/matlab/ref/quiver.html

You can do something like the following code, assuming both data-sets are 1-D matrices

for i=1:length(c13xi87) - 1
    p1 = [c13xi87(i) o18xi87(i)];
    p2 = [c13xi87(i+1) o18xi87(i+1)];
    dp = p2 - p1;
    quiver(p1(1),p1(2),dp(1),dp(2),0);
    hold on
end
hold off

[José-Luis]

Looping is unnecessary.

Answer 2

[Walter Roberson]

https://www.mathworks.com/matlabcentral/answers/92988-how-do-i-plot-a-line-that-has-an-arrow-on-the-end-of-it-in-2-d-and-3-d

[Walter Roberson]

Or possibly it would make sense to use stream2() or stream3() in connection with streamlines()

Answer 3

[José-Luis]

x = rand(10,1);                        
y = rand(10,1);                        
dx = diff(x);
dy = diff(y)
plot(x,y,'ro');
hold on
quiver(x(1:end-1),y(1:end-1),dx,dy,0)

[Farshid Tazesh]

Hi Jose. I used your code. Very helpfull. Thank you so much for sharing.

• Farshid