text_button=[['7','8','9','/','sqrt'],['4','5','6','*','%'],['1','2','3','-','1/x'],['0','+/-',',','+','=']]
index_row_cell=0
index_column_cell=0
b=0
c=0

for i in range(4):
    for j in range(5):
        bt=QtGui.QPushButton(text_button[b][c])
        kompanovka.addWidget(bt,index_row_cell,index_column_cell) 
        index_column_cell+=1
        c+=1
    b+=1
    c=0
    index_column_cell=0
    index_row_cell+=1

       def buttonConnect ( button, code ) :
            button.clicked.connect ( lambda : self.buttonClicked ( code ) )

        buttonConnect ( self.digitButton_0, '0' ); buttonConnect ( self.digitButton_1, '1' )
        buttonConnect ( self.digitButton_2, '2' ); buttonConnect ( self.digitButton_3, '3' )
        buttonConnect ( self.digitButton_4, '4' ); buttonConnect ( self.digitButton_5, '5' )
        buttonConnect ( self.digitButton_6, '6' ); buttonConnect ( self.digitButton_7, '7' )
        buttonConnect ( self.digitButton_8, '8' ); buttonConnect ( self.digitButton_9, '9' )
        buttonConnect ( self.pointButton, '.' ); buttonConnect ( self.changeSignButton, '+/-' )
        buttonConnect ( self.backspaceButton, 'b' ); buttonConnect ( self.clearButton, 'c' )
        buttonConnect ( self.divideButton, '/' ); buttonConnect ( self.multiplyButton, '*' )
        buttonConnect ( self.minusButton, '-' ); buttonConnect ( self.plusButton, '+' )
        buttonConnect ( self.equalButton, '=' ); buttonConnect ( self.squareRootButton, 'sqrt' )
        buttonConnect ( self.powerButton, 'x**2' ); buttonConnect ( self.reciprocalButton, '1/x' )
        buttonConnect ( self.percentButton, '%' )
        self.okButton.clicked.connect ( self.okButtonClicked )
 
    def buttonClicked ( self, code ) :
        expr = str ( self.display.text () )
        if code == 'b' : # backspace
            self.display.setText ( expr [ : -1 ]