在 matplotlib 交互式图中拖动点
我使用matplotlib并遵循此答案创建了一个交互式绘图。该图使用滑块以允许用户控制点的垂直（y 轴）位置，并在它们发生变化时为它们拟合样条曲线。完成此操作的代码在这里：
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最有助于做到这一点？我查看了各种小部件示例，但没有发现任何对我来说很容易看到的直接有用的东西。最接近的似乎是矩形选择器，但我不确定如何调整它以获得我需要的。
编辑：
这个答案可能适合做我需要的。这与我所需要的完全不同的是，该示例沿现有线选择一个点（基于鼠标单击和拖动）并突出显示它。我需要点击并选择哪个现有点在一个小范围内（如果没有，那么拖动应该什么都不做）。然后代码应该在拖动时更改该点，并在拖动操作期间重新调整样条线。我也许可以用上面的例子来做到这一点，因为它让我更好地理解如何使用mpl_connect不同的动作（并给出了一些示例动作。
最终的代码应该只允许垂直拖动点，但我认为这个约束很容易建立（即只使用鼠标单击/释放的 y 坐标）。
编辑2：
Poly Editor示例似乎非常接近我的需要，我可以从中开发。
Ok, relying heavily on the Poly Editor example, I have constructed an example that can either use the sliders to change the point values or click and drag the points.
The code is as follows, with diagnostic prints commented:
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()
I did not encapsulate the code into an object as the Poly Editor example did, but that should be an upgrade that is easy to do.
