PyQt集成Matplotlib时使用patchworklib无法显示多图求助

开发PyQt项目时，计划用patchworklib合并多个Matplotlib图形，但GUI中始终只显示一个图形。相关代码如下：

import sys

from matplotlib.figure import Figure
from PyQt5.QtWidgets import QApplication, QMainWindow, QVBoxLayout, QWidget
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
import matplotlib.pyplot as plt
import patchworklib as pw

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.initUI()

    def initUI(self):
        self.setWindowTitle('Matplotlib in PyQt5 Example')
        self.setGeometry(100, 100, 800, 600)

        central_widget = QWidget()
        self.setCentralWidget(central_widget)

        # 创建 Matplotlib 的画布
        self.canvas = PlotCanvas(self, width=5, height=4)
        layout = QVBoxLayout(central_widget)
        layout.addWidget(self.canvas)


class PlotCanvas(FigureCanvas):
    def __init__(self, parent=None, width=5, height=4, dpi=100):
        # fig, self.ax = plt.subplots(figsize=(width, height), dpi=dpi)
        # fig = Figure()
        self.ax1 = pw.Brick()
        self.ax2 = pw.Brick()

        ax1 = self.plot(self.ax1)
        ax2 = self.bar(self.ax2)
        # Concatenate axes
        ax12 = ax1 | ax2
        fig = ax12.savefig()
        super().__init__(fig)
        self.setParent(parent)
        self.draw()

    def plot(self, ax_):
        x = [1, 2, 3, 4, 5]
        y = [10, 20, 25, 30, 35]
        ax_.plot(x, y)
        ax_.set_title('Matplotlib Plot in PyQt5')
        ax_.set_xlabel('X Label')
        ax_.set_ylabel('Y Label')
        return ax_

    def bar(self, ax_):
        categories = ['A', 'B', 'C', 'D', 'E']
        values = [7, 10, 15, 5, 9]
        ax_.bar(categories, values, color='skyblue')
        ax_.set_title('Matplotlib Bar Chart in PyQt5')
        ax_.set_xlabel('Categories')
        ax_.set_ylabel('Values')
        return ax_


if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())

当前效果：

问题原因 #

代码中使用ax12.savefig()获取Figure是错误的，savefig()方法的作用是将合并后的图形保存为临时图片文件，并返回图片路径，而非返回Matplotlib的Figure对象。把路径传给FigureCanvas会导致无法正确渲染合并后的图形，仅显示单个子图。

解决方案 #

替换fig = ax12.savefig()为fig = ax12.figure，直接获取合并后的Figure对象，再传给FigureCanvas初始化。

修改后的完整代码 #

import sys

from matplotlib.figure import Figure
from PyQt5.QtWidgets import QApplication, QMainWindow, QVBoxLayout, QWidget
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
import matplotlib.pyplot as plt
import patchworklib as pw

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.initUI()

    def initUI(self):
        self.setWindowTitle('Matplotlib in PyQt5 Example')
        self.setGeometry(100, 100, 800, 600)

        central_widget = QWidget()
        self.setCentralWidget(central_widget)

        # 创建 Matplotlib 的画布
        self.canvas = PlotCanvas(self, width=5, height=4)
        layout = QVBoxLayout(central_widget)
        layout.addWidget(self.canvas)


class PlotCanvas(FigureCanvas):
    def __init__(self, parent=None, width=5, height=4, dpi=100):
        self.ax1 = pw.Brick()
        self.ax2 = pw.Brick()

        ax1 = self.plot(self.ax1)
        ax2 = self.bar(self.ax2)
        # Concatenate axes
        ax12 = ax1 | ax2
        # 获取合并后的Figure对象，替代savefig()
        fig = ax12.figure
        super().__init__(fig)
        self.setParent(parent)
        self.draw()

    def plot(self, ax_):
        x = [1, 2, 3, 4, 5]
        y = [10, 20, 25, 30, 35]
        ax_.plot(x, y)
        ax_.set_title('Matplotlib Plot in PyQt5')
        ax_.set_xlabel('X Label')
        ax_.set_ylabel('Y Label')
        return ax_

    def bar(self, ax_):
        categories = ['A', 'B', 'C', 'D', 'E']
        values = [7, 10, 15, 5, 9]
        ax_.bar(categories, values, color='skyblue')
        ax_.set_title('Matplotlib Bar Chart in PyQt5')
        ax_.set_xlabel('Categories')
        ax_.set_ylabel('Values')
        return ax_


if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())

修改后，两个图形会在PyQt的GUI中并排正常显示。

内容的提问来源于stack exchange，提问作者Dong Zhang