Can not put single artist in more than one figure

问题

Here is my issue.

I create a function that plot a list of circles. I need to plot my circle C1 first with a circle C2 then with C3.... until C40.

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

def plot_circle(Liste_circles):


    fig = plt.figure(figsize=(5,5))   
    ax = fig.add_subplot(111)

    # On définie un fond blanc
    ax.set_facecolor((1, 1, 1))

    ax.set_xlim(-5, 15)
    ax.set_ylim(-6, 12)    

    for c in Liste_circles:
        ax.add_patch(c)

    plt.show()

Now I create C1:

C1=Circle(xy=(3, 4), radius=2, fill=False, color='g')

An finally I try to plot it.
The first plot worked:

C2=Circle(xy=(6, 3), radius=4, fill=False, color='b')
plot_circle([C1,C2])

The second one failed:

C3=Circle(xy=(7, 2), radius=4, fill=False, color='b')
plot_circle([C1,C3])

with the error:

RuntimeError: Can not put single artist in more than one figure

I can make it worked by doing:

C1=Circle(xy=(3, 4), radius=2, fill=False, color='g')
C3=Circle(xy=(7, 2), radius=4, fill=False, color='b')
plot_circle([C1,C3])

How can I do to plot my circle C1 with 40 other circles without having to recreate C1 each time? (My program took 10min to create C1 throught a complicated algorithme, I cannot recreate it at each of the 40 plot....).

回答1:

Here is how to make it work: just do a copy of the circle and plot the copy:

First import copy:

from copy import copy

then, instead of doing:

for c in Liste_circles:
    ax.add_patch(c)

we have to do:

for c in Liste_circles:
   new_c=copy(c)
   ax.add_patch(new_c)

This way we won't plot the same circle (= the same artist) but its copy

回答2:

Moreover if you are interested you can set the x and y axes regarding the values of the circles:

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


def plot_circles (Liste_circles):

    if len(Liste_circles) == 0:
        print('No circles to display')
    else:

        fig = plt.figure(figsize=(5,5))   
        ax = fig.add_subplot(111)


        # On définie un fond blanc
        ax.set_facecolor((1, 1, 1))


        # On définie les limites des axes pour que nos cercles soient au centre de notre graphique
        # --> xmin sera le plus petit des x de tous les cercles - 2 fois le plus grand des rayons
        # --> xmax sera le plus grand des x de tous les cercles + 2 fois le plus grand des rayons
        # --> ymin sera le plus petit des y de tous les cercles - 2 fois le plus grand des rayons
        # --> ymax sera le plus grand des y de tous les cercles + 2 fois le plus grand des rayons
        L_x = [c.center[0] for c in Liste_circles]
        L_y = [c.center[1] for c in Liste_circles]
        L_r = [c.radius for c in Liste_circles]

        min_x=min(L_x); max_x=max(L_x);min_y=min(L_y); max_y=max(L_y);max_r=max(L_r)

        xmin = min_x - 2*max_r
        xmax = max_x + 2*max_r

        ymin = min_y - 2*max_r
        ymax = max_y + 2*max_r

        ax.set_xlim(xmin, xmax)
        ax.set_ylim(ymin, ymax)


        for c in Liste_circles:
            new_c=copy(c)
            ax.add_patch(new_c) 

        plt.show()

C1=Circle(xy=(3, 4), radius=2, fill=False, color='g')
C2=Circle(xy=(6, 3), radius=4, fill=False, color='b')
C3=Circle(xy=(7, 2), radius=4, fill=False, color='r')

来源：https://stackoverflow.com/questions/47554753/can-not-put-single-artist-in-more-than-one-figure