scope.py 文件源码

def draw_fft(self):
        if len(self.points) < 1:
            return
        pts = map(lambda p: p[1] - self.offset, self.points)

        out = numpy.fft.rfft(pts)
        c = len(out)

        norm = 0
        for i in range(c/2):
            norm += numpy.real(out[i])**2 + numpy.imag(out[i])**2

        norm = math.sqrt(norm)
        if norm <= 0:
            return

        for i in range(1, SignalKPlot.NUM_X_DIV):
            x = float(i) / SignalKPlot.NUM_X_DIV
            glRasterPos2d(x, .95)
            period = 3/math.exp(x) # incorrect!!
            SignalKPlot.drawputs(str(period))

        glPushMatrix()
        glBegin(GL_LINE_STRIP)
        for i in range(c/2):
            glVertex2d(float(i) * 2 / (c-2), abs(out[i]) / norm)
        glEnd()
        glPopMatrix()