GridLayout.py

import sys
from PyQt5.QtWidgets import QWidget, QGridLayout, QPushButton, QApplication

class Grid(QWidget):
	def __init__(self):
		super().__init__();
		self.initUI();

	def initUI(self):
		grid=QGridLayout();
		self.setLayout(grid);
		names=['Cls', 'Bck', '', 'Close',
				'7', '8', '9', '/',
				'4', '5', '6', '*',
				'1', '2', '3', '-',
				'0', '.', '=', '+']

		positions=[(i, j) for i in range(5) for j in range(4)];

		for position, name in zip(positions, names):
			if name=='':
				continue;
			button=QPushButton(name);
			grid.addWidget(button, *position);

		self.move(300, 150);
		self.setWindowTitle('Calculator');
		self.show();


if __name__=='__main__':
	app=QApplication(sys.argv);
	g=Grid();
	sys.exit(app.exec_());