Hey Vivek,
We just recently exposed the Color Encoding functionality for the TreeMap. It is currently available in our Unstable branch:
git checkout --track -b unstable origin/unstable
If you have the Unstable code, all you need to do is to set the preferredMinColor and preferredMaxColor treemap parameters.
-Sal
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Sal Uryasev
Juice Analytics
+1 (352) 213 9734