'Set the data/image to draw isocurves for.
**Arguments:**
data            A 2-dimensional ndarray.
level           The cutoff value at which to draw the curve. If level is not specified,
the previously set level is used.'

def setData(self, data, level=None):

    if (level is None):
        level = self.level
    self.level = level
    self.data = data
    self.path = None
    self.prepareGeometryChange()
    self.update()
