Sum values depending from another field value with Python

Question

I did a python script to do a query from the UF field from my attribute table. The code is very simple and works well. The output show me a map with the selected values.

Now I neeed to sum the values from another field (lets call this field "NEW") only from the selected features from UF field.

import arcpy

mxd = arcpy.mapping.MapDocument("CURRENT")  

for lyr in arcpy.mapping.ListLayers(mxd):  
    if lyr.name == "Brasil_Municipios":  
        lyr.definitionQuery = "UF = 'GO'"   
arcpy.RefreshActiveView()
arcpy.RefreshTOC()

I can get the SUM with Summary Tool, but how to print in the screen the result?

import arcpy  

mxd = arcpy.mapping.MapDocument("CURRENT")  
fc = 'G:\AgroBD.gdb\Brasil_Municipios'

for lyr in arcpy.mapping.ListLayers(mxd):  
    if lyr.name == "Brasil_Municipios":  
        lyr.definitionQuery = "UF = 'GO'"   
        arcpy.Statistics_analysis("Brasil_Municipios", 
 "G:\AgroBD.gdb\Brasil_Municipios2", [["media", "SUM"]], "")
arcpy.RefreshActiveView()
arcpy.RefreshTOC()

Answer 1

To summarize a field I would always use the Summary Statistics tool which I would expect to honour any current selection if used against a feature layer or table view.

I would use a SearchCursor to read the row that has the result you want first. Then, depending on whether your active view is the Layout View or the Data View, I would either update the text in a text element or update the value in a labeled point feature that you guarantee to be in the currently viewed extent.