On Sun, Oct 25, 2009 at 10:02 AM, Andrew Wittenberg
<Andrew.Wittenberg@xxxxxxxx> wrote:
Building on this suggestion, it'd be even better to have a "quantile transformation," e.g.
variable[t=@QNT:.5]
would return the temporal median and
variable[t=@QNT:.9]
would return the temporal 90th percentile.
Here's a sample script showing one way to do the quantile interpolation for a 1-dimensional time-oriented variable:
! Usage: go quantile variable_1d [quantile var_out]
! $1 [ $2 $3 ]
! Return a quantile of a one-dimensional variable.
! The quantile value is interpolated if necessary.
! Default is the median (0.5 quantile).
let q_idx = 1 + $2".5" * (`$1,r=lend`-1)
let q_sort = samplel($1,sortl(($1)))
let q_val = q_sort[t=`q_idx`]
let $3"quantile" = `q_val`
Andrew
David Wang wrote:
Dear Ferret developers,
I appreciate the recent, useful addition of median transformation smoother @MED into Ferret. Sometimes, however, I find myself (probably others as well) in need of a median averager, much like @AVE as an arithmetic averager. For instance, I'd like to get the median of a time series and use the resultant scalar in other expressions. I wonder if such a transformation could be implemented into future Ferret release.
Thanks,
David
--
turn and live.