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我正在尝试使用 matplotlib LassoSelector 从散点图中选择一些点，并只为选定的点生成一个单独的图形。当我尝试在第二个绘图上使用另一个 matplotlib 小部件时，它不起作用，但没有错误或警告消息。下面是一个使用 LassoSelector 和 SpanSelector 的最小示例。

我也尝试了其他小部件；Button 小部件显示按钮，但未执行按钮按下操作。

import numpy as np
from matplotlib.pyplot import *
from matplotlib.widgets import SpanSelector, LassoSelector
from matplotlib.path import Path

def onselect(verts):
    global xys,data

    #get indexes of selected points
    path = Path(verts)
    xysn = xys.get_offsets()
    ind = np.nonzero([path.contains_point(xy) for xy in xysn])[0]

    #plot the second figure
    fig=figure(2)
    ax=fig.add_subplot(111)
    ax.hist(data[:,0][ind],10)

    #this should be executed when SpanSelector is used
    def action(min,max):
        print min,max

    #try to do SpanSelector (this fails)
    span=SpanSelector(ax,action,'horizontal')

    show()

#initialize a figure
fig=figure(1)
ax=fig.add_subplot(111)

#create data
data=np.array([[1,6], [4,8],[0,4],[4,2],[9,6],[10,8],[2,2],[5,5],[0,4],[4,5]])

#plot data
xys=ax.scatter(data[:,0],data[:,1])

#select point by drawing a path around them
lasso = LassoSelector(ax, onselect=onselect)

show()
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1 回答 1

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matplotlib小部件是事件驱动的，所以等待用户输入。您的代码的问题是您正在尝试使用新的事件处理程序创建一个新图形SpanSelector。我不确定您是否可以根据以前的事件添加新事件并SpanSelector注释掉，我收到以下错误，

QCoreApplication::exec: The event loop is already running

因此，新事件LassoSelector未注册，用户输入未获取（并且新图形未出现）。最好在代码开头创建所有图形并注册所有可能的事件。以下应该更接近您想要做的事情，

import numpy as np
from matplotlib.pyplot import *
from matplotlib.widgets import SpanSelector, LassoSelector
from matplotlib.path import Path

#this should be executed when LassoSelector is used
def onselect(verts):
    global xys,data

    #get indexes of selected points
    path = Path(verts)
    xysn = xys.get_offsets()
    ind = np.nonzero([path.contains_point(xy) for xy in xysn])[0]

    #Clear and update bar chart
    h, b = np.histogram(data[:,0][ind],10)
    for rect, bars in zip(rects, h):
        rect.set_height(bars)
    ax2.bar(mb, h, align='center')
    draw()

#this should be executed when SpanSelector is used
def action(min,max):
    print min,max

#initialize figures
fig1=figure(1)
ax1=fig1.add_subplot(111)

fig2=figure(2)
ax2=fig2.add_subplot(111)

#create data
data=np.array([[1,6],[4,8],[0,4],[4,2],[9,6],[10,8],[2,2],[5,5],[0,4],[4,5]])

#plot data
xys=ax1.scatter(data[:,0],data[:,1])

#Plot initial histogram of all data
h, b = np.histogram(data[:,0],10)
mb = [0.5*(b[i]+b[i+1]) for i in range(b.shape[0]-1)]
rects = ax2.bar(mb, h, align='center')

#Register lasso selector
lasso = LassoSelector(ax1, onselect=onselect)

#Register SpanSelector 
span=SpanSelector(ax2,action,'horizontal')

show()

注意，为了更新条形图，它比绘图更棘手，所以我在这里使用了这个答案Dynamically updates a bar plot in matplotlib

出于某种原因，直方图图 2 仅在您单击它时才会更新。我会考虑为此使用带有两个轴的单个图形，这可能更容易使用，

fig, ax = subplots(2,1)
ax1 = ax[0]; ax2 = ax[1]
于 2016-07-05T08:24:53.597 回答