[idvusers] Formula to calculate a moving average at each grid point

[Wayt Gibbs <wayt@xxxxxxxxxxxxx>]

I know there must be a straightforward way to combine some of the  
existing Jython time series functions to do this, but I can't seem to  
figure it out: I have a time series of monthly temperature anomaly  
readings (over a global 2-D grid) in the parameter TREFHT and want to  
derive from this a new parameter TREFAVG that contains (at each point  
on the grid) the 12-month moving average. For example, if the temp  
anomaly over Chicago was
Jan     1
Feb     -1
Mar     2
Apr     0
May 3
Jun     -2
Jul     0
Aug     2
Sep     1
Oct     2
Nov     -4
Dec     0
then I need TREFAVG for the grid cell over Chicago in December to  
contain 0.33 (=sum(Jan-Dec)/12)). That same cell for Jan would contain  
sum(Feb-Jan)/12, etc.

I'm guessing the general strategy should be to define a new Jython  
function that calculates the average of the current value plus the  
preceding 11, then to use the applyToRange function to run it on the  
entire data series. But despite combing through the User's Guide  
section on the Jython Library and searching for relevant code  
examples, I can't seem to figure out the right syntax.

Any pointers would be most appreciated!

Wayt Gibbs
Intellectual Ventures