Python：xとyを更新せずにスキャターで領域を更新する方法

Question

xとyを引数としてもう一度与えなくても、関数scatterのs引数を更新する方法を知っている人はいますか？分散円のサイズが大きくなるアニメーションを作ろうとしていますが、私がそれを働かせる唯一の方法は、私が領域を更新するたびにxとyを引数として与えることです。

これは私が働いているコードです：

classplaceは私だけの領域を更新することができれば効率が道ずっと良くなるでしょうクラス定義

#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; 

を持つファイルである

#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() 

。 ありがとうございます！

Answer 1

scattermatplotlib.collections.PathCollectionオブジェクトを返します。そのメソッドget_sizes()とset_sizes()を使用して、ポイントのサイズを取得または設定することができます。ここにあなたの例の変更があります。

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)