matplotlib 动画在更新期间删除线条

Question

我已经创建了一张地图，并且正在将经纬度坐标的 CSV 文件读入 Pandas DataFrame。在读取 DataFrame 后，我已经成功地使用“for”循环绘制了多个大弧线。

当将一组新坐标添加到 CSV 时，将绘制一条新的大弧。

但是，一旦坐标被删除，我无法弄清楚如何删除一个大弧。这条线只是停留在地图上。

如何在每次更新 CSV 时删除所有旧线条并重新绘制线条？我只想查看当前包含在 CS 中的行。

CSV 包含以下内容：

sourcelon   sourcelat   destlon    destlat
50.44        30.51      -80.84      35.22
52.52        13.4       -80.84      35.22
43.18       -22.97      -80.84      35.22
44.1        -15.97      -80.84      35.22
55.44        30.51      -80.84      35.22

最少的代码如下：

from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import pandas as pd
import numpy as np
import matplotlib.animation


# setup mercator map projection.
fig = plt.figure(figsize=(27, 20))
m = Basemap(projection='mill', lon_0=0)
m.drawcoastlines(color='r', linewidth=1.0)


def animate(i):

    df = pd.read_csv('c:/python/scripts/test2.csv', sep='\s*,\s*',header=0, encoding='ascii', engine='python'); df 


    for x,y,z,w in zip(df['sourcelon'], df['sourcelat'], df['destlon'], df['destlat']):
        line, = m.drawgreatcircle(x,y,z,w,color='r')



ani = matplotlib.animation.FuncAnimation(fig, animate, interval=1000)

plt.tight_layout()
plt.show()

Answer 1

使用 blitting：

使用 blitting 时，线条会自动删除。

from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import pandas as pd
import numpy as np
import matplotlib.animation


# setup mercator map projection.
fig = plt.figure(figsize=(13, 8))
m = Basemap(projection='mill', lon_0=0)
m.drawcoastlines(color='grey', linewidth=1.0)

def get_data():
    a = (np.random.rand(4,2)-0.5)*300
    b = (np.random.rand(4,2)-0.5)*150
    df= pd.DataFrame(np.concatenate((a,b),axis=1),
                     columns=['sourcelon','destlon','sourcelat','destlat'])
    return df

def animate(i):
    df = get_data()
    lines = []
    for x,y,z,w in zip(df['sourcelon'], df['sourcelat'], df['destlon'], df['destlat']):
        line, = m.drawgreatcircle(x,y,z,w,color='r')
        lines.append(line)
    return lines

ani = matplotlib.animation.FuncAnimation(fig, animate, interval=1000, blit=True)

plt.tight_layout()
plt.show()

没有blitting：

如果不需要 blitting，可以手动删除这些行。

from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import pandas as pd
import numpy as np
import matplotlib.animation


# setup mercator map projection.
fig = plt.figure(figsize=(13, 8))
m = Basemap(projection='mill', lon_0=0)
m.drawcoastlines(color='grey', linewidth=1.0)

def get_data():
    a = (np.random.rand(4,2)-0.5)*300
    b = (np.random.rand(4,2)-0.5)*150
    df= pd.DataFrame(np.concatenate((a,b),axis=1),
                     columns=['sourcelon','destlon','sourcelat','destlat'])
    return df

lines = []

def animate(i):
    df = get_data()
    for line in lines:
        line.remove()
        del line
    lines[:] = []
    for x,y,z,w in zip(df['sourcelon'], df['sourcelat'], df['destlon'], df['destlat']):
        line, = m.drawgreatcircle(x,y,z,w,color='r')
        lines.append(line)

ani = matplotlib.animation.FuncAnimation(fig, animate, interval=1000)

plt.tight_layout()
plt.show()