Python 移动物体后如何更新箭图？

我正在写一个小的可视化项目，这个项目假设显示几个带电体周围的向量场

我的问题是： 我不知道如何在从主位置移动圆（带电粒子）后更新箭袋场

链接到图片，因为我的声誉太低。我对stackoverflow几乎是新手

from pylab import *
from scipy import *
import matplotlib.pyplot as plt
import matplotlib.patches as patches
import scipy.constants as const
skr = const.pi*const.epsilon_0*4

class DraggablePoint:
    def __init__(self, p, q0):
        self.q = q0
        self.point = p
        self.c_kruznice = p.center
        self.press = None

    def connect(self):
        self.cidpress = self.point.figure.canvas.mpl_connect('button_press_event', self.button_press_event) 
        self.cidrelease = self.point.figure.canvas.mpl_connect('button_release_event',self.button_release_event)   
        self.cidmotion = self.point.figure.canvas.mpl_connect('motion_notify_event', self.motion_notify_event)  

    def disconnect(self):
        self.point.figure.canvas.mpl_disconnect(self.cidpress)
        self.point.figure.canvas.mpl_disconnect(self.cidrelease)
        self.point.figure.canvas.mpl_disconnect(self.cidmotion)


    def button_press_event(self,event):
        if event.inaxes != self.point.axes:
            return
        contains = self.point.contains(event)[0]
        if not contains: return
        self.press = self.point.center, event.xdata, event.ydata


    def button_release_event(self,event):
        self.press = None
        self.point.figure.canvas.draw()

    def motion_notify_event(self, event):
        if self.press is None: return
        if event.inaxes != self.point.axes: return
        self.point.center, xpress, ypress = self.press
        dx = event.xdata - xpress
        dy = event.ydata - ypress
        self.point.center = (self.point.center[0]+dx, self.point.center[1]+dy)
        print(self.point.center)
        self.point.figure.canvas.draw()

if __name__ == '__main__':
    f_s=0.3
    def R(x,y):
        r=np.sqrt(x**2+y**2)+f_s
        return r

    def polje(tela, X, Y):
        Ex = 0
        Ey = 0
        for i in range(len(tela)):
            r=R(tela[i].c_kruznice[0] - X, tela[i].c_kruznice[1] - Y )
            ex = X - tela[i].c_kruznice[0]
            ey = Y - tela[i].c_kruznice[1]
            Ex += (tela[i].q/skr)*(1/(r+f_s)**3)*ex
            Ey += (tela[i].q/skr)*(1/(r+f_s)**3)*ey
        return Ex, Ey

    fig = plt.figure(figsize=(8,8))
    ax = fig.add_axes([0.05,0.05,0.92,0.92])
    ax.set_xlim(-6,6)
    ax.set_ylim(-6,6)
    scale = 0.2
    X,Y=np.mgrid[-5:5:scale, -5:5:scale]

    circles = []
    q=3*const.e
    s=abs(q)
    sx=sqrt(s/np.pi)*1e8*5
    circle2 = patches.Circle((3,0.3), 0.3, fc='r', alpha=0.5, picker=True)
    circle1 = patches.Circle((0.7,0.3), 0.3, fc='r', alpha=0.5, picker=True)
    circle = patches.Circle((-4,0.3), 0.3, fc='b', alpha=0.5, picker=True)
    circles.append(ax.add_patch(circle1))
    circles.append(ax.add_patch(circle))
    circles.append(ax.add_patch(circle2))
    drs = []

    for c in circles:
        print(c.center[0])
        dr = DraggablePoint(c,-1)
        dr.connect()
        drs.append(dr)

    racun=polje(drs, X, Y)
    ax.quiver(X,Y,racun[0],racun[1], color='r',  alpha=0.5)
    ax.quiver(X,Y,racun[0],racun[1], edgecolor='k', facecolor='None', linewidth =.5) 
    plt.show    ()  

---

我也是新来的，所以我会尽我所能帮助你

对我来说合乎逻辑的解决方案是为你们的圈子建立索引。每当你移动一个圆圈，你的类就会调用函数

按钮\u释放\u事件

尽可能多的圆圈。所以，当涉及到最后一个圆（你给它指定了具体的索引）时，你只需要删除你的绘图，然后重新做一遍（你需要画圆和字段）

有趣的是，当它检查圆时，它总是在第一个圆上完成，索引为0。我不知道为什么会发生这种情况，但这很好，因为它与图形上有多少圈无关

此外，还需要使用line

self.c_kruznice=self.point.center[0]，self.point.center[1]

，因为它将更新您拖动的点的中心，以便计算字段。关键的一点是：对绘图字段使用

plt.draw（）

，因为只有这样，拖动圆后才会更新字段。因为

plt.show（）

等待您完成绘制它的所有操作（这就是为什么在您开始下一次拖动时它会绘制），但是

plt.draw（）

在发布时进行绘制

编辑：在重新打印（我编辑了代码）之前，您需要清除列表

圆圈

下面是这个想法的代码

from pylab import *
from scipy import *
import matplotlib.pyplot as plt
import matplotlib.patches as patches
import scipy.constants as const

skr = const.pi*const.epsilon_0*4

class DraggablePoint:
    global Polje
    def __init__(self, p, q0, ind):
        self.q = q0
        self.point = p
        self.c_kruznice = p.center
        self.press = None
        self.indeks = ind

    def connect(self):
        self.cidpress = self.point.figure.canvas.mpl_connect('button_press_event', self.button_press_event)
        self.cidrelease = self.point.figure.canvas.mpl_connect('button_release_event',self.button_release_event)  
        self.cidmotion = self.point.figure.canvas.mpl_connect('motion_notify_event', self.motion_notify_event)  

    def disconnect(self):
        self.point.figure.canvas.mpl_disconnect(self.cidpress)
        self.point.figure.canvas.mpl_disconnect(self.cidrelease)
        self.point.figure.canvas.mpl_disconnect(self.cidmotion)

    def button_press_event(self,event):
        if event.inaxes != self.point.axes:
            return
        contains = self.point.contains(event)[0]
        if not contains: return
        self.press = self.point.center, event.xdata, event.ydata

    def button_release_event(self,event):
        self.press = None
        self.point.figure.canvas.draw()
        # This is the part which will erase field
        # and draw for us new one
        self.c_kruznice = self.point.center[0], self.point.center[1]
        if self.indeks == 0:
            racun = polje(drs, X, Y)
            ax.cla()
            circles = []
            circles.append(ax.add_patch(circle1))
            circles.append(ax.add_patch(circle))
            circles.append(ax.add_patch(circle2))
            circles.append(ax.add_patch(circle3))
            ax.quiver(X,Y,racun[0],racun[1], color='r',  alpha=0.5)
            ax.quiver(X,Y,racun[0],racun[1], edgecolor='k', facecolor='None', linewidth =.5)
            plt.draw()

    def motion_notify_event(self, event):
        if self.press is None: return
        if event.inaxes != self.point.axes: returnO
        self.point.center, xpress, ypress = self.press
        dx = event.xdata - xpress
        dy = event.ydata - ypress
        self.point.center = (self.point.center[0]+dx, self.point.center[1]+dy)
        self.point.figure.canvas.draw()


if __name__ == '__main__':
    f_s=0.3
    def R(x,y):
        r=np.sqrt(x**2+y**2)+f_s
        return r

    def polje(tela, X, Y):
        Ex = 0
        Ey = 0
        for i in range(len(tela)):
            r = R(tela[i].c_kruznice[0] - X, tela[i].c_kruznice[1] - Y )
            ex = X - tela[i].c_kruznice[0]
            ey = Y - tela[i].c_kruznice[1]
            Ex += (tela[i].q/skr)*(1/(r+f_s)**3)*ex
            Ey += (tela[i].q/skr)*(1/(r+f_s)**3)*ey
        return Ex, Ey


    fig = plt.figure(figsize=(8,8))
    ax = fig.add_axes([0.05,0.05,0.92,0.92])
    ax.set_xlim(-6,6)
    ax.set_ylim(-6,6)
    scale = 0.2
    X,Y=np.mgrid[-5:5:scale, -5:5:scale]

    circles = []
    q=3*const.e
    s=abs(q)
    sx=sqrt(s/np.pi)*1e8*5
    circle2 = patches.Circle((2,3), 0.3, fc='r', alpha=0.5, picker=True)
    circle1 = patches.Circle((2,-3), 0.3, fc='r', alpha=0.5, picker=True)
    circle = patches.Circle((-2,3), 0.3, fc='b', alpha=0.5, picker=True)
    circle3 = patches.Circle((-2,-3), 0.3, fc = 'b', alpha = 0.5, picker = True )
    circles.append(ax.add_patch(circle1))
    circles.append(ax.add_patch(circle))
    circles.append(ax.add_patch(circle2))
    circles.append(ax.add_patch(circle3))
    drs = []

    i = 0
    q = [-1, 1, -1, 1]
    for c in circles:
        dr = DraggablePoint(c, q[i], i)
        dr.connect()
        drs.append(dr)
        i += 1

    racun = polje(drs, X, Y)
    ax.quiver(X,Y,racun[0],racun[1], color='r',  alpha=0.5)
    ax.quiver(X,Y,racun[0],racun[1], edgecolor='k', facecolor='None', linewidth =.5)
    plt.show()

如果要为图像设置动画，请查看matplotlib.animation库。看看这个。这是个好主意，但不确定它是否简单。单击每个点时，它会触发自己的重绘。箭袋图取决于所有点的位置，因此可能不应在点移动事件中重新绘制。你可以破解一些东西，但是为了正确地完成它，你可能需要一个field类，包含所有与鼠标事件绑定的点。field类可以在更新字段时调用您已经拥有的点更新…我，某种程度上，修复了我的问题。”这段代码是有效的，但每次我移动一些圆圈时，我都需要再次单击以刷新箭袋字段。此外，只有一个补丁是完全可移动的，其他补丁在我尝试移动它们时只是取消了粘贴，然后在我“单击刷新”字段时再次重新绘制。我可以说它是有用的，买的很轻便。谢谢！！！这就是我想要的。在这之后，我在几秒钟内更新到N body visualization。