最小化QGridLayout中填充的小部件的空间

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QGridLayout, QLabel, QLineEdit

class Example(QWidget):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        grid = QGridLayout()
        grid.setSpacing(10)  # 设置小部件之间的间距

        label1 = QLabel('Label 1')
        label2 = QLabel('Label 2')
        label3 = QLabel('Label 3')
        label4 = QLabel('Label 4')

        lineEdit1 = QLineEdit()
        lineEdit2 = QLineEdit()
        lineEdit3 = QLineEdit()
        lineEdit4 = QLineEdit()

        # 设置小部件的大小策略
        label1.setSizePolicy(QSizePolicy.Minimum, QSizePolicy.Minimum)
        label2.setSizePolicy(QSizePolicy.Minimum, QSizePolicy.Minimum)
        label3.setSizePolicy(QSizePolicy.Minimum, QSizePolicy.Minimum)
        label4.setSizePolicy(QSizePolicy.Minimum, QSizePolicy.Minimum)

        lineEdit1.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Minimum)
        lineEdit2.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Minimum)
        lineEdit3.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Minimum)
        lineEdit4.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Minimum)

        grid.addWidget(label1, 0, 0)
        grid.addWidget(lineEdit1, 0, 1)
        grid.addWidget(label2, 1, 0)
        grid.addWidget(lineEdit2, 1, 1)
        grid.addWidget(label3, 2, 0)
        grid.addWidget(lineEdit3, 2, 1)
        grid.addWidget(label4, 3, 0)
        grid.addWidget(lineEdit4, 3, 1)

        self.setLayout(grid)

        self.setGeometry(300, 300, 300, 200)
        self.setWindowTitle('QGridLayout Example')
        self.show()

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