使用 matplotlib 的動畫交互式繪圖

Question

在尋找使用 matplotlib 制作動畫交互式繪圖的方法時，我在堆棧溢出文檔中遇到了這段代碼：

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from matplotlib.widgets import Slider

TWOPI = 2*np.pi

fig, ax = plt.subplots()

t = np.arange(0.0, TWOPI, 0.001)
initial_amp = .5
s = initial_amp*np.sin(t)
l, = plt.plot(t, s, lw=2)

ax = plt.axis([0,TWOPI,-1,1])

axamp = plt.axes([0.25, .03, 0.50, 0.02])
# Slider
samp = Slider(axamp, 'Amp', 0, 1, valinit=initial_amp)

def update(val):
    # amp is the current value of the slider
    amp = samp.val
    # update curve
    l.set_ydata(amp*np.sin(t))
    # redraw canvas while idle
    fig.canvas.draw_idle()

# call update function on slider value change
samp.on_changed(update)

plt.show()

這段代碼幾乎完全符合我的要求，但我希望為情節設置動畫，即讓滑塊自動從左向右移動，例如每秒 0.01 的進展。 有沒有什么簡單的方法可以做到這一點？ 知道我也想保持對滑塊的手動控制（使用點擊事件）。

Answer 1

您可以修改此答案中的代碼以包含滑塊。

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.animation import FuncAnimation
import mpl_toolkits.axes_grid1
import matplotlib.widgets

class Player(FuncAnimation):
    def __init__(self, fig, func, frames=None, init_func=None, fargs=None,
                 save_count=None, mini=0, maxi=100, pos=(0.125, 0.92), **kwargs):
        self.i = 0
        self.min=mini
        self.max=maxi
        self.runs = True
        self.forwards = True
        self.fig = fig
        self.func = func
        self.setup(pos)
        FuncAnimation.__init__(self,self.fig, self.update, frames=self.play(), 
                                           init_func=init_func, fargs=fargs,
                                           save_count=save_count, **kwargs )    

    def play(self):
        while self.runs:
            self.i = self.i+self.forwards-(not self.forwards)
            if self.i > self.min and self.i < self.max:
                yield self.i
            else:
                self.stop()
                yield self.i

    def start(self):
        self.runs=True
        self.event_source.start()

    def stop(self, event=None):
        self.runs = False
        self.event_source.stop()

    def forward(self, event=None):
        self.forwards = True
        self.start()
    def backward(self, event=None):
        self.forwards = False
        self.start()
    def oneforward(self, event=None):
        self.forwards = True
        self.onestep()
    def onebackward(self, event=None):
        self.forwards = False
        self.onestep()

    def onestep(self):
        if self.i > self.min and self.i < self.max:
            self.i = self.i+self.forwards-(not self.forwards)
        elif self.i == self.min and self.forwards:
            self.i+=1
        elif self.i == self.max and not self.forwards:
            self.i-=1
        self.func(self.i)
        self.slider.set_val(self.i)
        self.fig.canvas.draw_idle()

    def setup(self, pos):
        playerax = self.fig.add_axes([pos[0],pos[1], 0.64, 0.04])
        divider = mpl_toolkits.axes_grid1.make_axes_locatable(playerax)
        bax = divider.append_axes("right", size="80%", pad=0.05)
        sax = divider.append_axes("right", size="80%", pad=0.05)
        fax = divider.append_axes("right", size="80%", pad=0.05)
        ofax = divider.append_axes("right", size="100%", pad=0.05)
        sliderax = divider.append_axes("right", size="500%", pad=0.07)
        self.button_oneback = matplotlib.widgets.Button(playerax, label='$\u29CF$')
        self.button_back = matplotlib.widgets.Button(bax, label='$\u25C0$')
        self.button_stop = matplotlib.widgets.Button(sax, label='$\u25A0$')
        self.button_forward = matplotlib.widgets.Button(fax, label='$\u25B6$')
        self.button_oneforward = matplotlib.widgets.Button(ofax, label='$\u29D0$')
        self.button_oneback.on_clicked(self.onebackward)
        self.button_back.on_clicked(self.backward)
        self.button_stop.on_clicked(self.stop)
        self.button_forward.on_clicked(self.forward)
        self.button_oneforward.on_clicked(self.oneforward)
        self.slider = matplotlib.widgets.Slider(sliderax, '', 
                                                self.min, self.max, valinit=self.i)
        self.slider.on_changed(self.set_pos)

    def set_pos(self,i):
        self.i = int(self.slider.val)
        self.func(self.i)

    def update(self,i):
        self.slider.set_val(i)


### using this class is as easy as using FuncAnimation:            

fig, ax = plt.subplots()
x = np.linspace(0,6*np.pi, num=100)
y = np.sin(x)

ax.plot(x,y)
point, = ax.plot([],[], marker="o", color="crimson", ms=15)

def update(i):
    point.set_data(x[i],y[i])

ani = Player(fig, update, maxi=len(y)-1)

plt.show()

Answer 2

這是您的代碼的簡單改編以添加動畫：

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from matplotlib.widgets import Slider

TWOPI = 2*np.pi

fig, ax = plt.subplots()

t = np.arange(0.0, TWOPI, 0.001)
initial_amp = .5
s = initial_amp*np.sin(t)
l, = plt.plot(t, s, lw=2)

ax = plt.axis([0,TWOPI,-1,1])

axamp = plt.axes([0.25, .03, 0.50, 0.02])
# Slider
samp = Slider(axamp, 'Amp', 0, 1, valinit=initial_amp)

# Animation controls
is_manual = False # True if user has taken control of the animation
interval = 100 # ms, time between animation frames
loop_len = 5.0 # seconds per loop
scale = interval / 1000 / loop_len

def update_slider(val):
    global is_manual
    is_manual=True
    update(val)

def update(val):
    # update curve
    l.set_ydata(val*np.sin(t))
    # redraw canvas while idle
    fig.canvas.draw_idle()

def update_plot(num):
    global is_manual
    if is_manual:
        return l, # don't change

    val = (samp.val + scale) % samp.valmax
    samp.set_val(val)
    is_manual = False # the above line called update_slider, so we need to reset this
    return l,

def on_click(event):
    # Check where the click happened
    (xm,ym),(xM,yM) = samp.label.clipbox.get_points()
    if xm < event.x < xM and ym < event.y < yM:
        # Event happened within the slider, ignore since it is handled in update_slider
        return
    else:
        # user clicked somewhere else on canvas = unpause
        global is_manual
        is_manual=False

# call update function on slider value change
samp.on_changed(update_slider)

fig.canvas.mpl_connect('button_press_event', on_click)

ani = animation.FuncAnimation(fig, update_plot, interval=interval)

plt.show()

主要的變化是增加了update_plot函數，用於在FuncAnimation第二行制作FuncAnimation 。 動畫從設置的最后一個滑塊值開始遞增。

變量is_manual跟蹤用戶何時單擊滑塊。 用戶單擊它后，變量設置為True ，動畫將不再更新繪圖。

為了恢復動畫，我添加了一個on_click函數，當用戶單擊畫布上的某個地方而不是滑塊時，該函數設置is_manual = False 。

由於這是一個快速而骯臟的腳本，我將變量保留為全局變量，但您可以輕松地將其寫在適當的類中。

注意，調用samp.set_val隱式調用了update_slider函數，當用戶直接點擊滑塊時也會調用該函數，所以我們必須在update_plot函數中重置is_manual 。