Matplotlib可拖动数据m

Question

我需要一个可拖动的数据标记来手动调整数据集中的一组点。 Thisanswer和其他人使用补丁。圆圈. 不过，我需要标记保持相同的大小时，缩放的情节。有了圆，圆也会放大。我还没有试图找到一种方法，以动态调整大小的圆与每一个新的缩放，因为它看起来应该有一个更简单的方法，只是移动一个标记。有人知道怎么做吗？在

Answer 1

下面，我将展示一个MWE，它展示了一种使用matplotlib和PyQt4的面向对象API来实现这一点的方法。使用鼠标中键可以拖动数据标记。策略是使用line2D艺术家绘制数据，然后通过操纵艺术家的数据并更新绘图来拖动标记。这可以大致概括为三个步骤：

第1步-单击鼠标中键时，鼠标光标的坐标（以像素为单位）将与line2D Artister的xy数据（以像素为单位）进行比较。如果光标和最近的标记之间的线性距离小于给定值（此处定义为标记的大小），则该数据标记的索引将保存在类属性draggable中。否则，draggable被设置为None。在

第2步-移动鼠标时，如果draggable is not None，则将索引存储在类属性draggable中的数据标记的坐标设置为鼠标光标的坐标。在

第3步-松开鼠标中键时，draggable被设置回无。在

注意：如果需要，也可以使用pyplot接口来生成图形，而不是面向对象的API。在

import sys
from PyQt4 import QtGui
from matplotlib.figure import Figure
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg
from matplotlib.backends.backend_qt4agg import FigureManagerQT
import numpy as np


class MyFigureCanvas(FigureCanvasQTAgg):
    def __init__(self):
        super(MyFigureCanvas, self).__init__(Figure())
        # init class attributes:
        self.background = None
        self.draggable = None
        self.msize = 6
        # plot some data:
        x = np.random.rand(25)
        self.ax = self.figure.add_subplot(111)
        self.markers, = self.ax.plot(x, marker='o', ms=self.msize)
        # define event connections:
        self.mpl_connect('motion_notify_event', self.on_motion)
        self.mpl_connect('button_press_event', self.on_click)
        self.mpl_connect('button_release_event', self.on_release)

    def on_click(self, event):
        if event.button == 2:  # 2 is for middle mouse button
            # get mouse cursor coordinates in pixels:
            x = event.x
            y = event.y
            # get markers xy coordinate in pixels:
            xydata = self.ax.transData.transform(self.markers.get_xydata())
            xdata, ydata = xydata.T
            # compute the linear distance between the markers and the cursor:
            r = ((xdata - x)**2 + (ydata - y)**2)**0.5
            if np.min(r) < self.msize:
                # save figure background:
                self.markers.set_visible(False)
                self.draw()
                self.background = self.copy_from_bbox(self.ax.bbox)
                self.markers.set_visible(True)
                self.ax.draw_artist(self.markers)
                self.update()
                # store index of draggable marker:
                self.draggable = np.argmin(r)
            else:
                self.draggable = None

    def on_motion(self, event):
        if self.draggable is not None:
            if event.xdata and event.ydata:
                # get markers coordinate in data units:
                xdata, ydata = self.markers.get_data()
                # change the coordinate of the marker that is
                # being dragged to the ones of the mouse cursor:
                xdata[self.draggable] = event.xdata
                ydata[self.draggable] = event.ydata
                # update the data of the artist:
                self.markers.set_xdata(xdata)
                self.markers.set_ydata(ydata)
                # update the plot:
                self.restore_region(self.background)
                self.ax.draw_artist(self.markers)
                self.update()

    def on_release(self, event):
        self.draggable = None

if __name__ == '__main__':

    app = QtGui.QApplication(sys.argv)

    canvas = MyFigureCanvas()
    manager = FigureManagerQT(canvas, 1)
    manager.show()

    sys.exit(app.exec_())