[Matplotlib-users] Creating custom markers as the union of complex vertices

[Eric E. <eri...@es...>]

Hi

I have been looking for an elegant/simple (working!) solution to create 
new complex markers for matplotlib.

For example, I would like to design a new marker which is the union of a 
set of vertices, for example (just an example), two petals which are 
symmetric (see verts1 and verts2) and two lines above and below (see 
verts3, and verts4). I would also like to have the petal possibly filled 
(or not) and the edgecolor of each vertices with possibly various 
colours (one petal is blue, the other is orange). How should I proceed?

A naive way forward is to do something like (for a double petal, the 
left one not being filled up, the right one being filled, see the 
definition for verts1, verts2, verts3, verts4 below):

## Code
x = rand(10)
y = rand(10)
verts = [verts1, verts2, verts3, verts4]
fc = ['k', 'None', 'None', 'None']
ec = ['b', 'orange', 'k', 'k']

for lverts, lfc, lec in list(zip(verts, fc, ec)) :
      scatter(x, y, marker= (lverts, 0), facecolor=lfc, edgecolor=lec, 
s=1000, label='My symbol')

==> HOWEVER, since these are done in a for loop, it is not considered as 
a single marker when I do, for example, :

legend(loc=0)

QUESTION: how should I manage this? (couldn't find the answer on the net)

Suggestion are most welcome!

Thanks!
Eric
======================================
###### Definition for the vertices
if 1:
     # verts1:
     size, angrad = 10., 0.
     rx = 4. * size
     theta = np.linspace(-pi / 4., pi / 4., 151)
     x = rx*np.sqrt(cos(2.*theta))*cos(theta)
     y = rx*np.sqrt(cos(2.*theta))*sin(theta)
     rotx = x * cos(angrad) + y * sin(angrad)
     roty = -x * sin(angrad) + y * cos(angrad)
     verts1 = list(zip(rotx,roty))

     # verts2:
     size, angrad = 10.,  np.pi
     rx = 4. * size
     theta = np.linspace(-pi / 4., pi / 4., 151)
     x = rx*np.sqrt(cos(2.*theta))*cos(theta)
     y = rx*np.sqrt(cos(2.*theta))*sin(theta)
     rotx = x * cos(angrad) + y * sin(angrad)
     roty = -x * sin(angrad) + y * cos(angrad)
     verts2 = list(zip(rotx,roty))

     # verts3
     verts3 = list(zip([0.,0.],[0,0.1]))

     # verts4
     verts4 = list(zip([0.,0.],[-0.1,-0.03]))