matplotlib动画在更新期间删除线条

Posted 2021-03-31

我创建了一张地图，我正在以纬度和经度坐标的CSV格式读取到Pandas DataFrame中。在DataFrame中读取后，我成功地使用'for'循环绘制了多个大弧。

将一组新坐标添加到CSV时，将绘制一个新的大弧。

但是，一旦删除坐标，我无法弄清楚如何移除大弧。这条线只停留在地图上。

每次更新CSV时，如何删除所有旧行并重新绘制行？我只想查看CS中当前包含的行。

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

最小代码如下：

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()

答案

Using blitting:

使用blitting时，会自动删除线条。

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()

Without blitting:

如果不需要blitting，可以手动删除线。

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()