Scaling Subplots with PyQt ScrollArea

Question

Is there any way to set a fixed height of an inch for a dynamic number of subplots? What I've done is created a function that defines a scaling factor which display the subplot approximately an inch base on the number of subplots, but the problem comes when I'm outside the range of model function or adding one subplot at a time. Is there a more elegant solution that will always give me an exact inch? Thank you for any help. The code is taken from this example

from PyQt4 import QtGui, QtCore
import sys
import matplotlib

from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg
from matplotlib.figure                  import Figure


class Canvas(FigureCanvasQTAgg):

    def __init__(self, parent=None):
        self.figure = Figure()
        super(Canvas, self).__init__(self.figure)

        self.ax1 = self.figure.add_subplot(1,1,1)
        self.figure.subplots_adjust(left = 0.05, bottom = 0.02, right = 0.98, top = 0.99)
        self.setMinimumWidth(1000)
        self.ax1.plot([1,2,3])
        self.draw()

    def add_subplot(self, data=[]):
        rows = len(self.figure.axes) + 1
        for index, axes in enumerate(self.figure.axes, start=1):
            axes.change_geometry(rows, 1, index)

        ax = self.figure.add_subplot(rows, 1, index+1)
        ax.plot(data)
        ax.patch.set_facecolor('None')
        self.figure.set_figheight(self.figure.get_figheight()*self.figScalingfactor)

    def figScaling(self, numSubplot):
        self.figScalingfactor = round(1.1729*pow(numSubplot, -0.028),3)


class Window(QtGui.QMainWindow):

    def __init__(self):
        super(Window, self).__init__()

        self.showMaximized()
        self.widget = QtGui.QWidget()
        self.setCentralWidget(self.widget)
        self.widget.setLayout(QtGui.QVBoxLayout())
        self.widget.layout().setContentsMargins(0,0,0,0)
        self.widget.layout().setSpacing(5)

        self.canvas = Canvas(self)
        self.scroll = QtGui.QScrollArea(self.widget)
        self.scroll.setWidget(self.canvas)
        self.scroll.setWidgetResizable(False)
        self.numSubplots = 50
        self.canvas.figScaling(self.numSubplots)

        for x in range(self.numSubplots):
            self.canvas.add_subplot()
            self.canvas.adjustSize()
        self.canvas.draw()
        self.widget.layout().addWidget(self.scroll)

def main():
    app = QtGui.QApplication(sys.argv)
    app.aboutToQuit.connect(app.deleteLater)
    GUI = Window()
    GUI.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()