如何组合两个 PyQt5 代码

试试这样：

主文件

import sys
import os
import csv
from PyQt5.QtWidgets import QTableWidget, QApplication, \
    QMainWindow, QTableWidgetItem, QFileDialog, \
    QWidget, QGridLayout, QPushButton
from PyQt5.QtWidgets import qApp, QAction
from PyQt5.QtCore import Qt

from q1268638_2 import PlotCanvas                                    # +++


class MyTable(QTableWidget):
    def __init__(self, r, c):
        super().__init__(r, c)
        self.check_change = True
        self.init_ui()

    def init_ui(self):
        self.cellChanged.connect(self.c_current)
#        self.show()

    def c_current(self):
        if self.check_change:
            row = self.currentRow()
            col = self.currentColumn()
            value = self.item(row, col)
            value = value.text()
            print("The current cell is ", row, ", ", col)
            print("In this cell we have: ", value)

    def open_sheet(self):
        self.check_change = False
        path = QFileDialog.getOpenFileName(self, 'Open CSV', os.getenv('HOME'), 'CSV(*.csv)')
        if path[0] != '':
            with open(path[0]) as csv_file:
                self.setRowCount(0)
                self.setColumnCount(2)
                my_file = csv.reader(csv_file, dialect='excel')
                for row_data in my_file:
                    row = self.rowCount()
                    self.insertRow(row)
                    if len(row_data) > 2:
                        self.setColumnCount(len(row_data))
                    for column, stuff in enumerate(row_data):
                        item = QTableWidgetItem(stuff)
                        self.setItem(row, column, item)
        self.check_change = True

    def save_sheet(self):
        path = QFileDialog.getSaveFileName(self, 'Save CSV', os.getenv('HOME'), 'CSV(*.csv)')
        if path[0] != '':
            with open(path[0], 'w', newline='') as csv_file:
                writer = csv.writer(csv_file, dialect='excel')
                for row in range(self.rowCount()):
                    row_data = []
                    for column in range(self.columnCount()):
                        item = self.item(row, column)
                        if item is not None:
                            row_data.append(item.text())
                        else:
                            row_data.append('')
                    writer.writerow(row_data)


class Sheet(QMainWindow):
    def __init__(self):
        super().__init__()
        
        cent_widget = QWidget()                                             # +++
        self.setCentralWidget(cent_widget)                                  # +++

        self.form_widget = MyTable(10, 2)
#        self.setCentralWidget(self.form_widget)
        col_headers = ['x', 'y']
        self.form_widget.setHorizontalHeaderLabels(col_headers)

        # Set up menu
        bar = self.menuBar()
        file = bar.addMenu('Файл')

        save_action = QAction('&Сохранить', self)
        save_action.setShortcut('Ctrl+S')
        open_action = QAction('&Открыть', self)
        quit_action = QAction('&Выйти', self)

        file.addAction(save_action)
        file.addAction(open_action)
        file.addAction(quit_action)

        quit_action.triggered.connect(self.quit_app)
        save_action.triggered.connect(self.form_widget.save_sheet)
        open_action.triggered.connect(self.form_widget.open_sheet)
#        self.setGeometry(700, 300, 300, 500)
#        self.show()

# +++ vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
        self.plotCanvas = PlotCanvas(self, width=5, height=4)
        
        button = QPushButton('Кнопка')
        button.setToolTip('Подсказка')
        button.clicked.connect(self.onClicked)

        layout = QGridLayout(cent_widget)
        layout.addWidget(self.form_widget, 0, 0) 
        layout.addWidget(self.plotCanvas, 0, 1)
        layout.addWidget(button, 1, 0, 1, 2)
        
    def onClicked(self):
        columns = self.form_widget.columnCount()
        rows = self.form_widget.rowCount()
        x, y = [], []
        for col in range(2):             # columns
           for row in range(rows): 
               item = self.form_widget.item(row, col)
               if col == 0:
                   x.append(int(item.text()) if item else 0 )
               elif col == 1:
                   y.append(int(item.text()) if item else 0 )
        #print(x, y)
        
        self.plotCanvas.plot(x, y)
# +++ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    def quit_app(self):
        qApp.quit()


if __name__ == "__main__":
    app = QApplication(sys.argv)
    sheet = Sheet()
    sheet.show()
    sys.exit(app.exec_())

q1268638_2.py

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QMenu, QVBoxLayout, QSizePolicy, QMessageBox, QWidget, QPushButton
from PyQt5.QtGui import QIcon
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.figure import Figure
import matplotlib.pyplot as plt

class App(QMainWindow):

    def __init__(self):
        super().__init__()
        self.left = 600
        self.top = 300
        self.title = 'График'
        self.width = 640
        self.height = 400
        self.initUI()

    def initUI(self):
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)

        m = PlotCanvas(self, width=5, height=4)
        m.move(0,0)

        button = QPushButton('Кнопка', self)
        button.setToolTip('Подсказка')
        button.move(500,0)
        button.resize(100,20)

        self.show()

class PlotCanvas(FigureCanvas):

    def __init__(self, parent=None, width=5, height=4, dpi=100):
        fig = Figure(figsize=(width, height), dpi=dpi)
        FigureCanvas.__init__(self, fig)
        self.setParent(parent)

        FigureCanvas.setSizePolicy(self,
                QSizePolicy.Expanding,
                QSizePolicy.Expanding)
        FigureCanvas.updateGeometry(self)
        
        x = [0,1,2,3,4,5,6,7,8,9,10]                          # +
        y = [0,1,2,7,4,5,6,7,3,9,10]                          # +
        self.plot(x, y)                                       # + (x, y)

    def plot(self, x, y):                                     # + (x, y)
#        x = [0,1,2,3,4,5,6,7,8,9,10]
#        y = [0,1,2,7,4,5,6,7,3,9,10]
        ax = self.figure.add_subplot(111)
        ax.clear()                                            # +
        ax.plot(x, y, 'r-')
        ax.set_title('График')
        self.draw()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    sys.exit(app.exec_())