Python: Rotation value for text placed around the circle

Question

Here is the code snippet:

fig, ax = plt.subplots(figsize=(30, 20))
ax.axis('equal')

ax.set(xlim=(-10, 10), ylim=(-10, 10))

circle = plt.Circle((0, 0), 3.1, fc='cyan')
ax.add_patch(circle)

def kex(N):
    alpha=2*np.pi/N
    alphas = alpha*np.arange(N)
    coordX = np.cos(alphas)
    coordY = np.sin(alphas)

    return np.c_[coordX, coordY, alphas]

data = 'P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14'.split(' ')
radius = 3.3
points = kex(len(data))

for i in range(0, len(data)):
    a = points[i,2] 
    x,y = (radius*np.sin(a), radius*np.cos(a))
    
    a = a - 0.5*np.pi
    
    if points[i, 1] < 0:
        a = a - np.pi
    
    ax.text(x, y, data[i], rotation=np.rad2deg(a), ha="center", va="center", fontsize=15)
    
ax.axis("off")

plt.show()

I want to place the text around a circle but does not seem to find correct rotation values. Some code is taken from here I have tweaked some bits in the code but does not seem to find the correct rotation values. Can someone help?

Output is:

Edit 01:

I want something like this screenshot taken from here.

Your radius is 3.3 instead of 3.2. – Arundeep Chohan Aug 05 '20 at 18:26 — Arundeep Chohan, Aug 05 '20 at 18:26

tmdavison · Accepted Answer · 2020-08-06T08:29:48.587

You don't say exactly what your intended output should be. If its that the bottom of each text label lines up with the tangent of the circle, you are almost there; you can do this:

for i in range(0, len(data)):
    a = points[i,2] 
    x,y = (radius*np.sin(a), radius*np.cos(a))
       
    ax.text(x, y, data[i], rotation=-np.rad2deg(a), ha="center", va="center", fontsize=15)

i.e. remove the lines of code which modify a after you calculate x and y, and then use minus the angle a to set the rotation of the text.

To answer the edited question, you can simply use:

    if y < 0:
        a += np.pi

Python: Rotation value for text placed around the circle

1 Answers1