PyQtGraph：通过绘制数据切片发出循环

Question

我有一个 python class 生成大小为 10000 的 numpy 数组并对其执行一些计算。 class 有两种绘图方法，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，并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 的情况下更新绘图 window 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的 objective:

如果你想在焦点位于widget中时检测任意键的按下，那么只需覆盖window的keyPressEvent方法即可。
如果即使 window 没有按键，你也想检测任何按键的按下，那么你必须使用 OS 库，在 python 还好有pyinput、keyboard等wrapper

另一方面，逻辑是获取数据的碎片，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_()

PyQtGraph：通过绘制数据切片发出循环

PyQtGraph: Issue looping through plotting slices of data

python

pyqt5

pyqtgraph

qtgui

qapplication