I am customizing the script tool behaviour of a custom script and would like to get the min-max values from a raster self.params[0] and populate the next two parameters, self.params[1] and self.params[2], with these values. Here is what I have so far but of course, it doesn't work.

  def updateParameters(self):
    """Modify the values and properties of parameters before internal
    validation is performed.  This method is called whenever a parmater
    has been changed."""

    if self.params[0].altered and self.params[0].value:
        paramInRaster = arcpy.Raster(self.params[0])
        minVal = paramInRaster.minimum
        maxVal = paramInRaster.maximum
        self.params[1].value = minVal
        self.params[2].value = maxVal

1 Answer 1


In the following line, you are grabbing the parameter object instead of the value:

     paramInRaster = arcpy.Raster(self.params[0])

Try changing it to:

     paramInRaster = arcpy.Raster(self.params[0].value)

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