窗口小部件未在pyqt5中显示标签

Question

我想在pyqt5应用程序中显示一个带有简单消息的窗口。为此，我创建了一个简单的小部件，布局和标签。我将标签添加到布局中，然后将布局分配给小部件，如下所示：

app = QApplication(sys.argv)
# Create a widget to store information
load_widget = QWidget()
# Create a label with the message to display
load_label = QLabel()
# Set label text
load_label.setText('Data being imported, please wait...')
# Create a layout for the widget
load_layout = QVBoxLayout()
# Add label to the layout
load_layout.addWidget(load_label)
# Set layout for the widget
load_widget.setLayout(load_layout)
# Set window title
load_widget.setWindowTitle('Read SD')
# Show the widget
load_widget.show()
sys.exit(app.exec_())

但是，窗口与标题一起显示，但是没有标签显示，如下图所示。

Answer 1

@eyllanesc指出这不是MRE，因为如果复制/粘贴并运行它，则会得到：

DF <-
structure(list(Value = c(2L, 0L, 5L, 4L, 4L, 7L, 9L), Length = c(0L, 
1L, 1L, 5L, 5L, 6L, 8L)), class = "data.frame", row.names = c("Subject1", 
"Subject2", "Subject3", "Subject4", "Subject5", "Subject6", "Subject7"
))

我已经扩展了您的代码并对其进行了正确格式化，并且效果很好

QWidget: Must construct a QApplication before a QWidget