pyqtgraph中的UI绘图位置

import pyqtgraph as pg
from pyqtgraph.Qt import QtGui

app = QtGui.QApplication([])
win = pg.GraphicsLayoutWidget()
plot1 = win.addPlot(row=0, col=0)
plot2 = win.addPlot(row=1, col=0)
plot1.setGeometry(0, 0, 400, 300)
plot2.setGeometry(0, 300, 400, 300)
win.show()
app.exec_()

import pyqtgraph as pg
from pyqtgraph.Qt import QtGui

app = QtGui.QApplication([])
win = pg.PlotWidget()
win.setGeometry(0, 0, 400, 300)
win.show()
app.exec_()

import pyqtgraph as pg
from pyqtgraph.Qt import QtGui

app = QtGui.QApplication([])
view = pg.GraphicsView()
view.setGeometry(0, 0, 400, 300)
view.show()
app.exec_()