使用 PyQtGraph 进行数据切片

在本文中，我们将看到如何使用Python中的 PyQtGraph 模块执行数据切片。 PyQtGraph 是一个用于Python的图形和用户界面库，它提供了设计和科学应用程序中通常需要的功能。它的主要目标是提供用于显示数据（绘图、视频等）的快速交互式图形，其次是提供有助于快速应用程序开发的工具（例如，Qt Designer 中使用的属性树）。

为了安装 PyQtGraph，我们使用下面给出的命令

pip install pyqtgraph

多维数组中的切片是一列数据，对应于维度的一个或多个成员的单个值。切片是分割立方体以提取给定切片的信息的行为。这很重要，因为它可以帮助用户可视化和收集特定于维度的信息。当您考虑切片时，可以将其视为维度中特定值的专用过滤器。一个简单的数据切片任务是针对给定的 3D 数据选择 2D 平面并沿该平面插入数据以生成切片图像。

为此，我们必须执行以下操作

导入所需的库，如 pyqtgraph、pyqt5 和 numpy
使用pyqt5创建一个主窗口类
创建一个图形窗口以添加显示切片所需的小部件
在布局中创建两个图像视图对象，第一个显示整个 3d 数据，第二个显示切片
创建一个 roi 对象并将其添加到第一个图像视图以选择切片
创建一个 3d 数据并将其添加到图像视图
当区域改变时，将一个update方法连接到roi对象，在update方法中获取区域并将其设置为第二个图像视图
将此图形窗口添加到带有任何其他小部件的主窗口布局。

下面是实现。

Python3

# importing Qt widgets
from PyQt5.QtWidgets import *
  
# importing system
import sys
  
# importing numpy as np
import numpy as np
  
# importing pyqtgraph as pg
import pyqtgraph as pg
from PyQt5.QtGui import *
from PyQt5.QtCore import *
  
  
class Window(QMainWindow):
  
    def __init__(self):
        super().__init__()
  
        # setting title
        self.setWindowTitle("PyQtGraph")
  
        # setting geometry
        self.setGeometry(100, 100, 700, 550)
  
        # icon
        icon = QIcon("skin.png")
  
        # setting icon to the window
        self.setWindowIcon(icon)
  
        # calling method
        self.UiComponents()
  
        # showing all the widgets
        self.show()
  
    # method for components
    def UiComponents(self):
  
        # creating a widget object
        widget = QWidget()
  
        # text
        text = "Data Slicing"
  
        # creating a label
        label = QLabel(text)
  
        # setting minimum width
        label.setMinimumWidth(130)
  
        # making label do word wrap
        label.setWordWrap(True)
  
        # creating a window for graphs
        win = QMainWindow()
  
        # creating a widget object
        cwid = QWidget()
  
        # setting central widget to the graph window
        win.setCentralWidget(cwid)
  
        # creating a grid layout
        lay = QGridLayout()
  
        # setitng grid layout to central widget of graphs
        cwid.setLayout(lay)
  
        # creating a image view objects
        imv1 = pg.ImageView()
        imv2 = pg.ImageView()
  
        # adding image view objects to the layout
        lay.addWidget(imv1, 0, 0)
        lay.addWidget(imv2, 1, 0)
  
        # creating a ROI object for selecting slice
        roi = pg.LineSegmentROI([[30, 64], [100, 64]], pen='r')
  
        # add roi to image view 1
        imv1.addItem(roi)
  
        # creating 3d data
        # x value using numpy
        x1 = np.linspace(-30, 10, 128)[:, np.newaxis, np.newaxis]
        x2 = np.linspace(-20, 20, 128)[:, np.newaxis, np.newaxis]
  
        # y value using numpy
        y = np.linspace(-30, 10, 128)[np.newaxis, :, np.newaxis]
        z = np.linspace(-20, 20, 128)[np.newaxis, np.newaxis, :]
  
        # dimension 1 values
        d1 = np.sqrt(x1 ** 2 + y ** 2 + z ** 2)
  
        # dimension 2 values
        d2 = 2 * np.sqrt(x1[::-1] ** 2 + y ** 2 + z ** 2)
  
        # dimension 3 value
        d3 = 4 * np.sqrt(x2 ** 2 + y[:, ::-1] ** 2 + z ** 2)
  
        # whole data ie all 3 dimensions
        data = (np.sin(d1) / d1 ** 2) + \
            (np.sin(d2) / d2 ** 2) + (np.sin(d3) / d3 ** 2)
  
        # method to update the image view 2
        def update():
  
            # get the roi selected data from image view 1
            d2 = roi.getArrayRegion(data, imv1.imageItem, axes=(1, 2))
  
            # update the image view 2 data
            imv2.setImage(d2)
  
        # adding update method to the roi
        # when region is changed this method get called
        roi.sigRegionChanged.connect(update)
  
        # Display the data in both image view
        imv1.setImage(data)
  
        # setting the range of image view
        imv1.setHistogramRange(-0.01, 0.01)
  
        # setting levels of the image view
        imv1.setLevels(-0.003, 0.003)
  
        # call the update method
        update()
  
        # Creating a grid layout
        layout = QGridLayout()
  
        # minimum width value of the label
        label.setMinimumWidth(130)
  
        # setting this layout to the widget
        widget.setLayout(layout)
  
        # adding label in the layout
        layout.addWidget(label, 1, 0)
  
        # plot window goes on right side, spanning 3 rows
        layout.addWidget(win, 0, 1, 3, 1)
  
        # setting this widget as central widget of the main widow
        self.setCentralWidget(widget)
  
  
# create pyqt5 app
App = QApplication(sys.argv)
  
# create the instance of our Window
window = Window()
  
# start the app
sys.exit(App.exec())

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