Matplotlib change color of a specific point

I can't change the color of the single that is clicked. The idea is to change the color of a point in red after a click on, and turn back the other in blue if he was selected before and in red, to keep only a point "active", so in red. But what happens now in the program is that only when I click on the 9th point placed (at the top right), all points change their color to become red. And when I click on the others, nothing happend

import matplotlib.pyplot as plt
from matplotlib.patches import Circle

fig, ax = plt.subplots()

liste_points = [(1, 1, "a"), (2, 1, "b"), (3, 1, "c"), (1, 2, "d"), (2, 2, "e"), (3, 2, "f"), (1, 3, "g"), (2, 3, "h"), (3, 3, "i")]
x, y, labels = zip(*liste_points)
sc = ax.scatter(x, y, s=10, c="blue", picker=5)

def onpick(event):
    point_choisi = event.artist
    index = event.ind[0]
    for i, point in enumerate(sc.get_offsets()):
        if i == index:
            point_choisi.set_color('red')
        else:
            point_choisi.set_color('blue')
    fig.canvas.draw_idle()

fig.canvas.mpl_connect('pick_event', onpick)

plt.show()

The other idea would be to print the tag associated to the point clicked, which turns in red (so the letter)

One simple option is to make an array of the scatter's color (c can be array-like), then set_facecolor of the clicked point to red (based on the PickEvent.ind) right after you reset all the colors to blue (if any red) :

on, off = "r", "b"

fig, ax = plt.subplots()

sc = ax.scatter(x, y, s=50, c=off, picker=5)

def on_pick(event):
    _new_colors = np.full(len(liste_points), off) # make sure all blue
    _new_colors[event.ind] = on                   # then set a red one
    sc.set_facecolor(_new_colors)
    fig.canvas.draw()

fig.canvas.mpl_connect("pick_event", on_pick)

plt.show()