interactive_pyplot.py

%pip install ipympl
%matplotlib ipympl

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.widgets import Slider

# draw initial triangle
triangle = np.array([
    [1, 4, 1, 1],
    [3, 5, 4, 3]
])
fig, ax = plt.subplots()
ax.set_xlim(-10, 10)
ax.set_ylim(-10, 10)
ax.grid(True)
ax.scatter(0, 0, color='red')
plot, = ax.plot(triangle[0], triangle[1])

# define rotation updates
def rotation_2D(theta):
    return np.array([
        [np.cos(theta), -np.sin(theta)],
        [np.sin(theta), np.cos(theta)],
    ])
    
def update(theta):
    T = rotation_2D(theta)
    T_triangle = T @ triangle
    plot.set_data(T_triangle[0], T_triangle[1])
    fig.canvas.draw_idle()

# add a slider UI
fig.subplots_adjust(bottom=0.25)
ax = fig.add_axes([0.25, 0.1, 0.65, 0.03])
slider = Slider(
    ax=ax,
    label='rotation',
    valmin=0,
    valmax=6,
    valinit=0,
)
slider.on_changed(update)

# show canvas
plt.show()