PyQtGraph - 设置折线图中线的Alpha值

在本文中，我们将看到如何在 PyQtGraph 模块的折线图中设置线的 alpha 值。 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。其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。折线图或折线图或折线图或曲线图是一种将信息显示为一系列称为“标记”的数据点的图表' 由直线段连接。它是许多领域中常见的一种基本类型的图表。线图是在 PyQtGraph 中的绘图类的帮助下创建的。 alpha 值是一个介于 0.0（完全透明）和 1.0（完全不透明）之间的数字。
我们可以在下面给出的命令的帮助下创建一个绘图窗口并在其上创建线条

# creating a pyqtgraph plot window
plt = pg.plot()

# ploting line in green color
# with dot symbol as x, not a mandatory field
line = plt.plot(x, y, pen='g', symbol='x', symbolPen='g', symbolBrush=0.2, name='green')

In order to do this we use setAlpha method with the line object
Syntax : line.setAlpha(n, False)
Argument : It takes float(alpha) value and bool(auto) as argument
Return : It returns None 
 

下面是实现

Python3

# importing Qt widgets
from PyQt5.QtWidgets import * import sys
 
# importing pyqtgraph as pg
import pyqtgraph as pg
from PyQt5.QtGui import *
 
# Bar Graph class
class BarGraphItem(pg.BarGraphItem):
 
    # constructor which inherit original
    # BarGraphItem
    def __init__(self, *args, **kwargs):
        pg.BarGraphItem.__init__(self, *args, **kwargs)
 
    # creating a mouse double click event
    def mouseDoubleClickEvent(self, e):
 
        # setting scale
        self.setScale(0.2)
 
 
 
class Window(QMainWindow):
 
    def __init__(self):
        super().__init__()
 
        # setting title
        self.setWindowTitle("PyQtGraph")
 
        # setting geometry
        self.setGeometry(100, 100, 600, 500)
 
 
        # 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()
 
        # creating a new label
        label = QLabel("GeeksforGeeks Line Plot")
 
        # making it multiline
        label.setWordWrap(True)
 
        # y values to plot by line 1
        y = [2, 8, 6, 8, 6, 11, 14, 13, 18, 19]
 
        # y values to plot by line 2
        y2 = [3, 1, 5, 8, 9, 11, 16, 17, 14, 16]
        x = range(0, 10)
 
        # create plot window object
        plt = pg.plot()
 
        # showing x and y grids
        plt.showGrid(x = True, y = True)
 
        # adding legend
        plt.addLegend()
 
        # set properties of the label for y axis
        plt.setLabel('left', 'Vertical Values', units ='y')
 
        # set properties of the label for x axis
        plt.setLabel('bottom', 'Horizontal Values', units ='s')
 
        # setting horizontal range
        plt.setXRange(0, 10)
 
        # setting vertical range
        plt.setYRange(0, 20)
 
        # ploting line in green color
        # with dot symbol as x, not a mandatory field
        line1 = plt.plot(x, y, pen ='g', symbol ='x', symbolPen ='g', symbolBrush = 0.2, name ='green')
 
        # ploting line2 with blue color
        # with dot symbol as o
        line2 = plt.plot(x, y2, pen ='b', symbol ='o', symbolPen ='b', symbolBrush = 0.2, name ='blue')
 
        # setting alpha value of the line 1
        line1.setAlpha(0.4, False)
 
        # setting alpha value of the line 2
        line2.setAlpha(0.5, False)
 
        
 
        # label minimum width
        label.setMinimumWidth(150)
 
        # Creating a grid layout
        layout = QGridLayout()
 
        # setting this layout to the widget
        widget.setLayout(layout)
 
        # adding label to the layout
        layout.addWidget(label, 1, 0)
 
        # plot window goes on right side, spanning 3 rows
        layout.addWidget(plt, 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())

输出 ：