在matplotlib互动情节

Question

我使用matplotlib和this回答后创建了一个交互式图。该图使用滑块以允许用户控制点的垂直（y轴）位置，并在更改时将样条拟合到它们。完成此任务的代码如下：

import matplotlib.animation as animation
from matplotlib.widgets import Slider
import matplotlib as mpl
from matplotlib import pyplot as plt
import scipy.interpolate as inter
import numpy as np



func = lambda x: 0.1*x**2

#get a list of points to fit a spline to as well
N = 10
xmin = 0
xmax = 10
x = np.linspace(xmin,xmax,N)

#spline fit
yvals = func(x)
spline = inter.InterpolatedUnivariateSpline (x, yvals)

#figure.subplot.right
mpl.rcParams['figure.subplot.right'] = 0.8

#set up a plot
fig,axes = plt.subplots(1,1,figsize=(9.0,8.0),sharex=True)
ax1 = axes


interval = 100 # ms, time between animation frames
loop_len = 5.0 # seconds per loop
scale = interval / 1000 / loop_len

def update(val):
  # update curve
  for i in np.arange(N):
    yvals[i] = sliders[i].val
  l.set_ydata(yvals)
  spline = inter.InterpolatedUnivariateSpline (x, yvals)
  m.set_ydata(spline(X))
  # redraw canvas while idle
  fig.canvas.draw_idle()

X = np.arange(0,xmax+1,0.1)
ax1.plot (X, func(X), 'k--', label='original')
l, = ax1.plot (x,yvals,color='k',linestyle='none',marker='o',markersize=8)
m, = ax1.plot (X, spline(X), 'r-', label='spline')



ax1.set_yscale('linear')
ax1.set_xlim(0, xmax)
ax1.set_ylim(0,xmax)
ax1.set_xlabel('x')
ax1.set_ylabel('y')
ax1.grid(True)
ax1.yaxis.grid(True,which='minor',linestyle='--')
ax1.legend(loc=2,prop={'size':22})

sliders = []

for i in np.arange(N):

    axamp = plt.axes([0.84, 0.8-(i*0.05), 0.12, 0.02])
    # Slider
    s = Slider(axamp, 'p{0}'.format(i), 0, 10, valinit=yvals[i])
    sliders.append(s)


for i in np.arange(N):
    #samp.on_changed(update_slider)
    sliders[i].on_changed(update)


plt.show()

我认为如果可以直接点击这些点并垂直向上或向下拖动它们，用户界面会更好。 matplotlib交互式代码的哪些功能对此最有帮助？我查看了各种widgets examples，但没有找到任何容易让我看到对此直接有用的内容。最近似乎是rectangle selector，但我不确定如何调整它以获得我需要的东西。

编辑：

This答案可能会适应我所需要的。这与我需要的区别在于，该示例沿现有线选取一个点（基于鼠标单击并拖动）并突出显示它。我需要单击并选择哪个现有点在一个小范围内（如果没有，那么拖动应该什么也不做）。然后代码应该在拖动时更改该点，并在该拖动操作期间重新设置样条线。我可以通过上面的示例来做到这一点，因为它让我更好地理解如何使用mpl_connect进行不同的操作（并给出了一些示例操作。

最终代码应该只允许垂直拖动点，但我认为该约束很容易构建（即只使用鼠标点击/释放的y坐标）。

编辑2：

The Poly Editor示例似乎非常接近我需要的东西，我可以从中发展出来。

Answer 1

好的，严重依赖于Poly Editor示例，我构建了一个示例，可以使用滑块更改点值，也可以单击并拖动点。

代码如下，诊断打印已注释：

import matplotlib.animation as animation
from matplotlib.widgets import Slider, Button
import matplotlib as mpl
from matplotlib import pyplot as plt
import scipy.interpolate as inter
import numpy as np



func = lambda x: 0.1*x**2

#get a list of points to fit a spline to as well
N = 10
xmin = 0 
xmax = 10 
x = np.linspace(xmin,xmax,N)

#spline fit
yvals = func(x)
spline = inter.InterpolatedUnivariateSpline (x, yvals)

#figure.subplot.right
mpl.rcParams['figure.subplot.right'] = 0.8

#set up a plot
fig,axes = plt.subplots(1,1,figsize=(9.0,8.0),sharex=True)
ax1 = axes


pind = None #active point
epsilon = 5 #max pixel distance

def update(val):
    global yvals
    global spline
    # update curve
    for i in np.arange(N):
      yvals[i] = sliders[i].val 
    l.set_ydata(yvals)
    spline = inter.InterpolatedUnivariateSpline (x, yvals)
    m.set_ydata(spline(X))
    # redraw canvas while idle
    fig.canvas.draw_idle()

def reset(event):
    global yvals
    global spline
    #reset the values
    yvals = func(x)
    for i in np.arange(N):
      sliders[i].reset()
    spline = inter.InterpolatedUnivariateSpline (x, yvals)
    l.set_ydata(yvals)
    m.set_ydata(spline(X))
    # redraw canvas while idle
    fig.canvas.draw_idle()

def button_press_callback(event):
    'whenever a mouse button is pressed'
    global pind
    if event.inaxes is None:
        return
    if event.button != 1:
        return
    #print(pind)
    pind = get_ind_under_point(event)    

def button_release_callback(event):
    'whenever a mouse button is released'
    global pind
    if event.button != 1:
        return
    pind = None

def get_ind_under_point(event):
    'get the index of the vertex under point if within epsilon tolerance'

    # display coords
    #print('display x is: {0}; display y is: {1}'.format(event.x,event.y))
    t = ax1.transData.inverted()
    tinv = ax1.transData 
    xy = t.transform([event.x,event.y])
    #print('data x is: {0}; data y is: {1}'.format(xy[0],xy[1]))
    xr = np.reshape(x,(np.shape(x)[0],1))
    yr = np.reshape(yvals,(np.shape(yvals)[0],1))
    xy_vals = np.append(xr,yr,1)
    xyt = tinv.transform(xy_vals)
    xt, yt = xyt[:, 0], xyt[:, 1]
    d = np.hypot(xt - event.x, yt - event.y)
    indseq, = np.nonzero(d == d.min())
    ind = indseq[0]

    #print(d[ind])
    if d[ind] >= epsilon:
        ind = None

    #print(ind)
    return ind

def motion_notify_callback(event):
    'on mouse movement'
    global yvals
    if pind is None:
        return
    if event.inaxes is None:
        return
    if event.button != 1:
        return

    #update yvals
    #print('motion x: {0}; y: {1}'.format(event.xdata,event.ydata))
    yvals[pind] = event.ydata 

    # update curve via sliders and draw
    sliders[pind].set_val(yvals[pind])
    fig.canvas.draw_idle()

X = np.arange(0,xmax+1,0.1)
ax1.plot (X, func(X), 'k--', label='original')
l, = ax1.plot (x,yvals,color='k',linestyle='none',marker='o',markersize=8)
m, = ax1.plot (X, spline(X), 'r-', label='spline')



ax1.set_yscale('linear')
ax1.set_xlim(0, xmax)
ax1.set_ylim(0,xmax)
ax1.set_xlabel('x')
ax1.set_ylabel('y')
ax1.grid(True)
ax1.yaxis.grid(True,which='minor',linestyle='--')
ax1.legend(loc=2,prop={'size':22})

sliders = []

for i in np.arange(N):

    axamp = plt.axes([0.84, 0.8-(i*0.05), 0.12, 0.02])
    # Slider
    s = Slider(axamp, 'p{0}'.format(i), 0, 10, valinit=yvals[i])
    sliders.append(s)


for i in np.arange(N):
    #samp.on_changed(update_slider)
    sliders[i].on_changed(update)

axres = plt.axes([0.84, 0.8-((N)*0.05), 0.12, 0.02])
bres = Button(axres, 'Reset')
bres.on_clicked(reset)

fig.canvas.mpl_connect('button_press_event', button_press_callback)
fig.canvas.mpl_connect('button_release_event', button_release_callback)
fig.canvas.mpl_connect('motion_notify_event', motion_notify_callback)

plt.show()

我没有像Poly Editor示例那样将代码封装到对象中，但这应该是一个易于升级的升级。