Custom format column / tooltip via IronPython or TERR

I have a visualization that plots from a data table that is being replaced by a TERR function every time a marking is changed.  The problem is that my custom formatting for the table columns is lost every time the table is replaced.   Basically I want a few of my tooltips based on my columns to have a custom number format that I've defined. Every time I remark, the table is replaced, and the formatting is lost.   I've thought about a few different solutions:

  • Format the table in TERR using some kind of attr($map) function, and the formatting should be inherited by the tooltip
  • Format the table columns in Python -  but the formatting is not being inherited by the tooltip
  • Format the tooltip directly - no idea how to do this.

Anyone have any ideas?

Here's the column formatting code:

formatter.GroupSeparatorEnabled = 1 # not sure what this does
# I actually want to apply a Custom Short number format that I've defined

for cc in table.Columns:
	if cc.Name == "myCol":    


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