plot arrow in polarplot() (not cartesian axes)

I need help to draw an arrow to a polar plot (e.g. to indicate resultant vector).

I am using the new polarplot() function as opposed to the old polar() or polarhistogram() functions. Thus I cannot (to my knowledge) use functions like quiver because this would be plotted onto cartesian axes (the polarplot() function, unlike polar(), actually uses polar axes, and you can't mix up cartesian and polar child axes, as far as I know).

As far as I can see, possible solutions would be:

1. simulate an arrow by calculating and drawing an arrow shape from lots of little lines using the polarplot() function, or

2. somehow merging cartesian and polar children plots onto the same figure (if this is possible) to make use of older arrow functions (e.g. quiver or compass).

This post seeks any better suggestions, and/or solutions to the above.

Thanks!

N.B. The choice to use the polarplot() function was based on better control of axis appearance (which you don't seem to get with polar() function), and better control of histogram bar aesthetics (which you don't seem to get with polarhistogram() function...)

Answer 1

[Jack Supple]

I ended up using method 1 in the question (1. simulate an arrow by calculating and drawing an arrow shape from lots of little lines using the polarplot() function). It seems to work alright, I'm sure there must be better methods. Posting code for others

polar plot arrow

    %%%Data %%%%
    resultant_direction = rand(1)*2*pi;
    resultant_length = 0.5 + (1-0.5).*rand(1);

    %%%%arrow head %%%%
    arrowhead_length    = resultant_length/15; % arrow head length relative to resultant_length
    num_arrowlines = 100;
    arrowhead_angle = deg2rad(30); % degrees

    %%%%arrow tip coordinates %%%%
    t1 = repmat(resultant_direction,1,num_arrowlines);
    r1 = repmat(resultant_length,1,num_arrowlines);

    %%%%arrow base coordinates %%%%
    b = arrowhead_length.*tan(linspace(0,arrowhead_angle,num_arrowlines/2));
    theta = atan(b./(resultant_length-arrowhead_length));
    pre_t2 = [theta, -theta];
    r2 = (resultant_length-arrowhead_length)./cos(pre_t2);
    t2 = t1(1)+pre_t2;

    %%%%plot %%%%
    figure(1)
    polarplot([t1(1) t1(1)],[0 r1(1)-0.9*arrowhead_length],'r','linewidth',3)
    hold on
    polarplot([t1; t2],[r1; r2],'r')

[Xiaoyu Zhao]

Well done and thanks for your solution!