def okClicked(self): if self.data_in_table == False: Control.errorMessage( "Please upload satellite imagery from your data folder.") return self.OK.setCursor(QtGui.QCursor(QtCore.Qt.BusyCursor)) attrs = ["ndvi", "rsr", "rvsi", "reip"] attrs_values = [] for image in S2.images: for attr in attrs: attrs_values.append(getattr(image, attr)) if True not in attrs_values: Control.errorMessage( "Please select at least one vegetation index to calculate.") else: self.getResults() Control.closeWindow(self, SecondPage())