help with addfiles function

Hi. Could I have some help? I am trying to use the addfiles function
to access a variable across multiple wrfout files. When I expect to 30
timesteps of a variable, I end up getting 270, and I am not sure why.
I have thirty files, where each have 9 time-steps (8, if counting from
zero). Using the ncdump command, the first file's time-steps are:
data:

 Times =
  "2006-09-01_00:00:00",
  "2006-09-01_03:00:00",
  "2006-09-01_06:00:00",
  "2006-09-01_09:00:00",
  "2006-09-01_12:00:00",
  "2006-09-01_15:00:00",
  "2006-09-01_18:00:00",
  "2006-09-01_21:00:00",
  "2006-09-02_00:00:00" ;
}

With addfiles, variables aggregated across multiple files opened are
accessed using square brackets to reference the file list elements,
like this:
rainc_agg = f[:]->RAINC
I want to access only each eighth step of the aggregated time
dimension, instead of ALL time-steps (270), similar to "Example 4"
here on the NCL addfiles page:
http://www.ncl.ucar.edu/Document/Functions/Built-in/addfiles.shtml
So, Likewise, I do the following, hoping to get 30 timesteps:
ncl 11> f = addfiles (fils+".nc", "r")
ncl 12> ListSetType (f, "cat") ; concatenate (=default)
ncl 13> raincBIG = f[:]->RAINC(::8,:,:) ; read RAINC with a stride
of 8
ncl 14> printVarSummary(raincBIG)

Variable: raincBIG
Type: float
Total Size: 16508800 bytes
            4127200 values
Number of Dimensions: 3
Dimensions and sizes: [Time | 270] x [south_north | 110] x [west_east | 140]
Coordinates:
Number Of Attributes: 6
  FieldType : 104
  MemoryOrder : XY
  description : ACCUMULATED TOTAL CUMULUS PRECIPITATION
  units : mm
  stagger :
  coordinates : XLONG XLAT

Instead, I get 270 timesteps. How can I adjust this so that I only
get: [Time | 30] x [south_north | 110] x [west_east | 140]?
Thanks for the help
-Erik
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Received on Mon Apr 27 2009 - 16:33:43 MDT