Python：如何在不更新x和y的情况下更新分散区域

有人知道如何更新函数scatter的s参数而不必再次将x和y作为参数吗？我正在尝试制作一个散射圆尺寸增大的动画，但唯一能让它工作的方法是每次更新区域时都要将x和y作为参数

这是我正在研究的代码：

#population plot
#plots a graph of the input from a file

import matplotlib.pyplot as plt;
import classplace as p;
import matplotlib.animation as amt

def animate(i, population, latitude, longitude, colour):
        scalefactor = 0.00005;
        area = [];
        for n in population:
            area.append(n*scalefactor*i);

        plt.scatter(longitude, latitude, s = area, c = colour); 
        del area;     
try:
    readFile = open("GBplaces.csv", "r");

except:
    print("Something went wrong! Can't open the file GBplaces.csv!\n");

else:
    header = False;
    places = [];

    #stores the data in a list, where each element of the list is of class place, converting when necessary.
    #Stores the header in a string
    for line in readFile:
        if(line[0] != '%'):
            words = line.rstrip();
            words = words.split(',');
            places.append(p.Place(words[0], words[1], int(words[2]), float(words[3]), float(words[4])));

    #closes readFile
    readFile.close();

    #creates an array of colours where cities are green and towns are yellow
    #creates an array of longitude
    #creates an array of latitude
    #creates an array of population

    colour = [];
    longitude = [];
    latitude = [];
    population = [];

    for n in range(p.Place.numcities + p.Place.numtowns):
        if(places[n].tipe == "City"): colour.append("g");
        else: colour.append("y");

        longitude.append(places[n].longitude);
        latitude.append(places[n].latitude);
        population.append(places[n].population);

    fig = plt.figure();

    ani = amt.FuncAnimation(fig, animate, frames=50, fargs = (population, latitude, longitude, colour), interval=0.1, repeat = False, blit = False)
    plt.show()

其中classplace是具有类定义的文件

#classplace.py
#place class definition

class Place:
    numcities = 0;
    numtowns = 0;

    def __init__(self, name, tipe, population, latitude, longitude):
        self.name = name;
        self.tipe = tipe;
        self.population = population;
        self.latitude = latitude;
        self.longitude = longitude;

        if(self.tipe == "City"): Place.numcities += 1;
        elif(self.tipe == "Town"): Place.numtowns += 1;
        else:
            print("Instance is not allowed. You need to specify if %s is a City or Town.\n" %(self.name));
            del self;

如果我能只更新这个区域，效率就会大大提高。

---

谢谢你的帮助

scatter

返回

matplotlib.collections.PathCollection

对象。您可以使用其方法

get_size（）

和

set_size（）

检索或设置点的大小。下面是对您的示例的修改

import matplotlib.pyplot as plt;
import matplotlib.animation as amt

# to embed animation as html5 video in Jupyter notebook
from matplotlib import rc
rc('animation', html='html5')

def animate(i, population, latitude, longitude, colour):
    scalefactor = 0.001
    area = [n*scalefactor*i for n in population]
    # it is better to use list comprehensions here

    sc.set_sizes(area)
    # here is the answer to the question

    return (sc,)

#creates an array of colours where cities are green and towns are yellow
#creates an array of longitude
#creates an array of latitude
#creates an array of population

# pick some random values

colour = ['g', 'g', 'y', 'y', 'y'];
longitude = [1, 2, 3, 4, 5];
latitude = [1, 3, 2, 5, 4];
population = [1000, 2000, 5000, 4000, 3000];

fig = plt.figure()
sc = plt.scatter(longitude, latitude, s=population)

# I didn't managed this to work without `init` function

def init():
    return (sc,)

ani = amt.FuncAnimation(fig, animate, frames=200, init_func=init,
                        fargs=(population, latitude, longitude, colour), 
                        interval=10, repeat = False, blit = True)

---

scatter

返回

matplotlib.collections.PathCollection

对象。您可以使用其方法

get_size（）

和

set_size（）

检索或设置点的大小。下面是对您的示例的修改

import matplotlib.pyplot as plt;
import matplotlib.animation as amt

# to embed animation as html5 video in Jupyter notebook
from matplotlib import rc
rc('animation', html='html5')

def animate(i, population, latitude, longitude, colour):
    scalefactor = 0.001
    area = [n*scalefactor*i for n in population]
    # it is better to use list comprehensions here

    sc.set_sizes(area)
    # here is the answer to the question

    return (sc,)

#creates an array of colours where cities are green and towns are yellow
#creates an array of longitude
#creates an array of latitude
#creates an array of population

# pick some random values

colour = ['g', 'g', 'y', 'y', 'y'];
longitude = [1, 2, 3, 4, 5];
latitude = [1, 3, 2, 5, 4];
population = [1000, 2000, 5000, 4000, 3000];

fig = plt.figure()
sc = plt.scatter(longitude, latitude, s=population)

# I didn't managed this to work without `init` function

def init():
    return (sc,)

ani = amt.FuncAnimation(fig, animate, frames=200, init_func=init,
                        fargs=(population, latitude, longitude, colour), 
                        interval=10, repeat = False, blit = True)