python - PyQtGraph:通过绘制数据切片发出循环

Question

我有一个 python 类，它生成一个大小为 10000 的 numpy 数组并对其执行一些计算。该类有两个绘图方法，都使用 pyqtgraph

• 绘制整个数据
• 一次绘制数据段(200 个样本)

我想知道如何循环遍历数据段(一次 200 个样本)并将处理后的数据显示给用户，然后等到用户按下任意键后再绘制下一个 200 个样本？

我希望能够在不关闭 Qt 窗口的情况下更新绘图，以通过仅更新已绘制对象的内容来实现更高效的性能。

import numpy as np
from pyqtgraph.Qt import QtCore, QtGui
import pyqtgraph as pg

class testqt:

    def __init__(self):
        self.data = np.random.randn(10000) # for the sake of providing a MWE
        self.do_some_processing()

    def do_some_processing(self):
        self.data_processed = 2*self.data

    def plot_entire_processed_data(self):
        # Plot the entire processed data
        win = pg.GraphicsLayoutWidget(show=True)
        p = win.addPlot()
        curve_data = p.plot(self.data_processed)
        QtGui.QApplication.instance().exec_()

    def plot_processed_data_every_200(self):
        # animate the processed data in segments of 200 samples
        win = pg.GraphicsLayoutWidget(show=True)
        p = win.addPlot()
        curve_data = p.plot(self.data_processed[:200])

        for i in range(200, len(self.data_processed), 200):
            curve_data.setData(self.data_processed[i:i+200])
            # How can I pause here and use keyboard to move to the next 200 samples?
            # I would like to be able to visually evaluate each segment first and then 
            # press any key to see the next segment


        QtGui.QApplication.instance().exec_() # unfortunately, this only plot the last 200 samples


a = testqt()
a.plot_entire_processed_data()
a.plot_processed_data_every_200()

如有任何帮助或提示，我将不胜感激。

Answer 1

要检测键盘事件，有几个选项取决于具体目标:

• 如果您想在焦点位于小部件中时检测任意键的按下，则只需重写窗口的 keyPressEvent 方法即可。

• 如果你想在窗口没有键的情况下检测任何键的按下，那么你必须使用操作系统库，幸运的是在 python 中有包装器，如 pyinput、键盘等。

另一方面，逻辑是获取数据片段，所以要做到这一点，只需使用生成器函数即可。

考虑第一种情况，解决方案是:

import numpy as np
from pyqtgraph.Qt import QtCore, QtGui
import pyqtgraph as pg


def iter_by_step(data, step):
    for i in range(0, len(data), step):
        yield data[i : i + step]


class GraphicsLayoutWidget(pg.GraphicsLayoutWidget):
    def __init__(self, parent=None):
        super().__init__(parent)

        self.data = np.random.randn(10000)
        self.iter = None

        curve = self.addPlot()
        self.p = curve.plot()

    def do_some_processing(self):
        self.data_processed = 2 * self.data
        self.iter = iter_by_step(self.data_processed, 200)
        self.plot_processed_data_every_200()

    def keyPressEvent(self, event):
        super().keyPressEvent(event)
        if self.iter is not None:
            self.plot_processed_data_every_200()

    def plot_processed_data_every_200(self):
        try:
            data = next(self.iter)
        except StopIteration:
            pass
        else:
            self.p.setData(data)


if __name__ == "__main__":

    w = GraphicsLayoutWidget()
    w.show()
    w.do_some_processing()

    QtGui.QApplication.instance().exec_()