@mutia

This is a plotly.py question. Please change its category from Plotly.js to Plotly.py.

Here is a function that draws the ellipse as a line:

```
import numpy as np
from numpy import pi, sin, cos
import plotly.graph_objects as go
def ellipse(x_center=0, y_center=0, ax1 = [1, 0], ax2 = [0,1], a=1, b =1, N=100):
# x_center, y_center the coordinates of ellipse center
# ax1 ax2 two orthonormal vectors representing the ellipse axis directions
# a, b the ellipse parameters
if np.linalg.norm(ax1) != 1 or np.linalg.norm(ax2) != 1:
raise ValueError('ax1, ax2 must be unit vectors')
if abs(np.dot(ax1, ax2)) > 1e-06:
raise ValueError('ax1, ax2 must be orthogonal vectors')
t = np.linspace(0, 2*pi, N)
#ellipse parameterization with respect to a system of axes of directions a1, a2
xs = a * cos(t)
ys = b * sin(t)
#rotation matrix
R = np.array([ax1, ax2]).T
# coordinate of the ellipse points with respect to the system of axes [1, 0], [0,1] with origin (0,0)
xp, yp = np.dot(R, [xs, ys])
x = xp + x_center
y = yp + y_center
return x, y
#EXAMPLE
fig = go.Figure()
x_center=1
y_center=0.75
x, y = ellipse_arc(x_center=x_center, y_center=y_center,
ax1 =[cos(pi/6), sin(pi/6)], ax2=[-sin(pi/6),cos(pi/6)],
a=3, b =2)
fig.add_scatter(
x=x,
y=y,
mode = 'lines')
fig.update_layout(width =600, height=525)
```