Question

我试图通过允许用户鼠标点击位置来使用'ginput'来测量matplotlib图中的距离。我可以在matplotlib图中独立完成此操作，但是当我尝试将图形设置到matplotlib画布上然后将其嵌入到PyQt4小部件中时，我遇到了问题。下面是我的代码，其中大部分来自matplotlib示例。我的解决方案是单击一组位置，并将（x，y）坐标传递给'dist_calc'函数以获得距离。

import sys
from PyQt4 import QtGui
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar
import matplotlib.pyplot as plt
from matplotlib.figure import Figure
import random
import numpy as np

class Window(QtGui.QWidget):
def __init__(self, parent=None):
    super(Window, self).__init__(parent)
    self.fig = Figure((6.5, 5.0), tight_layout=True)
    self.ax = self.fig.add_subplot(111)
    self.canvas = FigureCanvas(self.fig)
    self.toolbar = NavigationToolbar(self.canvas, self)

    self.button = QtGui.QPushButton('Plot')
    self.button.clicked.connect(self.plot)

    self.ndist = QtGui.QPushButton('Measure')
    self.ndist.clicked.connect(self.draw_line)

    self.toolbar.addWidget(self.button)
    self.toolbar.addWidget(self.ndist)
    self.fig.tight_layout()
    layout = QtGui.QVBoxLayout()
    layout.addWidget(self.toolbar)
    layout.addWidget(self.canvas)
    self.setLayout(layout)

def plot(self):
    data = [random.random() for i in range(20)]
    self.ax.hold(False)                          
    self.ax.plot(data, '*-')                     
    self.canvas.draw()                      

def draw_line(self):
    self.xy = plt.ginput(0)
    x = [p[0] for p in self.xy]
    y = [p[1] for p in self.xy]
    self.ax.plot(x,y)
    self.ax.figure.canvas.draw()
    self.get_dist(x, y)

def get_dist(self, xpts, ypts):
    npts = len(xpts)
    distArr = []
    for i in range(npts-1):
        apt = [xpts[i], ypts[i]]
        bpt = [xpts[i+1], ypts[i+1]]
        dist =self.calc_dist(apt,bpt)
        distArr.append(dist)

    tdist = np.sum(distArr)
    print(tdist)

def calc_dist(self,apt, bpt):
    apt = np.asarray(apt)
    dist = np.sum((apt - bpt)**2)
    dist = np.sqrt(dist)
    return dist

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    main = Window()
    main.show()
    sys.exit(app.exec_())

Answer 1

一位领先的Matplotlib开发人员根据this comment，当你在Mattlotlib中嵌入Matplotlib时，你必须不导入pyplot。 Pyplot设置了自己的gui，mainloop和canvas，它们干扰了Qt事件循环。

将行self.xy = plt.ginput(0)更改为self.xy = self.fig.ginput(0)并没有帮助，但却提出了一个有洞察力的错误：

AttributeError: 'FigureCanvasQTAgg' object has no attribute 'manager'
Figure.show works only for figures managed by pyplot, normally created by pyplot.figure().

简而言之，我不认为这是可能的。 ginput是一个阻塞函数，似乎只是为Matplotlib事件循环实现的。我担心您必须使用Matplotlib mouse events构建所需的功能，在嵌入PyQt时执行工作。请务必不要使用pyplot！

修改：我记得，或许LassoSelector就是你所需要的。

在PyQt4中使用嵌入式matplotlib图中的ginput

1 个答案: