Convert plotted graph to (x,y) coordinates?

Hi all,

I have a plotted graph and I wanted to know if it is possible to "convert" the plot by the graph() function to a plot in a (x,y) axis (like a scatter plot), but it is very important that is preserves the look of the plot! Is this possible in any way?

Thank you very much!

[KSSV]

If you have data (x,y) in hand....use scatter

[Felipe Schuback]

Hi - thanks for your answer. I already managed to plot de x,y coordinates corresponding to the graph plot. Do you know how to draw an arrow between points in the scatter plot? And if it is possible to draw lines and arrow-lines in the same scatter plot?

Best

[José-Luis]

You could use quiver() and superimpose it to your plot.

[Felipe Schuback]

But would it be possible to format the line of the arrow using quiver()? For example, get it colored, or make it dashed?

[José-Luis]

Yes

[Felipe Schuback]

thank you very much for the help!

[Felipe Schuback]

Hi José-Luis! I plotted a quiver arrow to join two points in my scatter plot and the formatting of this arrow is really important to get my task done. When I tried to, for example, format the LineStyle to '--' (dashed), the arrow head also became dashed. Is it possible to format the arrow stem only? I would like to format the arrow stem (dashed, etc) but maintaining the arrow head line style as solid line. Is this possible in any way?

Besides that, how do I choose the direction of the arrow in quiver plot?

[José-Luis]

Not gonna happen automagically, please see answer below.

You choose the direction by defining the starting point and the vector direction. I don't think it's just an option you can change. You'd need to reverse that.

Please accept the answer that best solves your problem.

[Walter Roberson]

You asked about the solid head in a new Question. I answered there:

h = quiver(...., 'LineStyle', '--')   %use the linestyle appropriate for the body
h.Head.LineStyle = 'solid';           %magic property, magic property value, notice this is not '-'

[José-Luis]

I stand corrected. It apparently can happen automagically.

Only downside to it being undocumented is that it's, well, undocumented and can change without warning in a new release.

Prettier than my answer though.

[Felipe Schuback]

Hi José! thank you VERY much for your help!! but just so I get it correctly... what exactly is undocumented and can change without warning?

[Walter Roberson]

The "Head" property of quiver objects is not documented.

[Felipe Schuback]

Got it. Thank you very much. One other thing I am struggling with... how can I color individual markers in scatter? I would test to see if condition is met for that marker, in case it is, color it red for example. is this possible?

[Walter Roberson]

Sorry, only one color is possible for any one call to scatter()

[Felipe Schuback]

I managed to do the individual coloring by inputting a color matrix when I call the scatter function. Is it possible to change the line colors in the scatter plot? Set all of them to black, for example?

[Walter Roberson]

Ah yes, I forgot for a moment about specifying the individual colors for scatter().

scatter() plots do not have line colors.

If you are referring to quiver(), then you can use the 'Color' option to set the same color for all of the lines; however, it is not possible to use different colors for different lines in any one quiver() call.

Answer 1

[José-Luis]

It ain't pretty but it works. As far as I understand there are no simple options you can set to get the look you want.

 data = rand(10,4);
 qH = quiver(data(:,1),data(:,2),data(:,3),data(:,4),0);
 hold on
 qH1 = quiver(data(:,1),data(:,2),data(:,3),data(:,4),0);
 colorVector = rand(1,3);
 qH2 = quiver(data(:,1),data(:,2),data(:,3),data(:,4),0);
 colorVector = rand(1,3);

 qH.LineStyle = '-';
 qH.Color = colorVector;

 qH1.LineStyle = '-';
 qH1.Color = 'w';
 qH1.ShowArrowHead = 'off';

 qH2.LineStyle = '--';
 qH2.Color = colorVector;
 qH2.ShowArrowHead = 'off';