pyqt5 formatting using multiple layouts

Question

I have 4 labels and need first 1st 2 table on the first row and next 2 on the second row.

The below code works fine but the row spans the whole screen.

import sys

from PyQt5.QtWidgets import QWidget, QApplication, QDialog, QGridLayout, QLabel, QLineEdit
from PyQt5.Qt import QHBoxLayout, QWindow, QMainWindow, QVBoxLayout


class Example(QMainWindow):
    def __init__(self, *args, **kwargs):
        super(Example, self).__init__(*args, **kwargs)            
        self.initUI()

    def initUI(self):
        vlayout = QVBoxLayout()
        hlayout1 = QHBoxLayout()
        hlayout2 = QHBoxLayout()
        widget = QWidget()
        widget.setLayout(vlayout)

        a1 = QLabel('label1')
        a2 = QLabel('label2')
        hlayout1.addWidget(a1)
        hlayout1.addWidget(a2)
        hlayout1.addStretch(2)
        vlayout.addLayout(hlayout1)
        vlayout.addStretch(1)
        a3 = QLabel('label3')
        a4 = QLabel('label3')
        hlayout2.addWidget(a3)
        hlayout2.addWidget(a4)
        hlayout2.addStretch(1)
        vlayout.addLayout(hlayout2)
        vlayout.addStretch(1)

        self.setCentralWidget(widget)

        self.setGeometry(500, 500, 500, 500)
        self.setWindowTitle('Lines')
        self.show()


if __name__ == '__main__':

    app = QApplication(sys.argv)
    ex = Example()
#     ex.show()
    sys.exit(app.exec_())

Answer 1

Delete the line vlayout.addStretch(1)

import sys

from PyQt5.QtWidgets import QWidget, QApplication, QDialog, QGridLayout, QLabel, QLineEdit
from PyQt5.Qt        import QHBoxLayout, QWindow, QMainWindow, QVBoxLayout


class Example(QMainWindow):
    def __init__(self, *args, **kwargs):
        super(Example, self).__init__(*args, **kwargs)            
        self.initUI()

    def initUI(self):
        vlayout = QVBoxLayout()
        hlayout1 = QHBoxLayout()
        hlayout2 = QHBoxLayout()
        widget = QWidget()
        widget.setLayout(vlayout)

        a1 = QLabel('label1')
        a2 = QLabel('label2')
        hlayout1.addWidget(a1)
        hlayout1.addWidget(a2)
        hlayout1.addStretch(2)
        vlayout.addLayout(hlayout1)
        #vlayout.addStretch(1)        # < ---- 
        a3 = QLabel('label3')
        a4 = QLabel('label3')
        hlayout2.addWidget(a3)
        hlayout2.addWidget(a4)
        hlayout2.addStretch(1)
        vlayout.addLayout(hlayout2)
        vlayout.addStretch(1)

        self.setCentralWidget(widget)

        self.setGeometry(500, 500, 500, 500)
        self.setWindowTitle('Lines')
        self.show()


if __name__ == '__main__':

    app = QApplication(sys.argv)
    ex = Example()
#     ex.show()
    sys.exit(app.exec_())