Hi Tim,
Im a netcdf programmer -It may be possible to write a custom
operator for nco tool "ncap2" that calculates quartiles
Regards Henry
Roy Mendelssohn wrote:
R has functions for trimmed means also,
-Roy M.
On May 11, 2008, at 8:09 PM, Roy Mendelssohn wrote:
R. And it has netcdf functions also.
-Roy M.
On May 11, 2008, at 8:07 PM, Timothy Hume wrote:
I think the reason why functions for calculating quartiles (or more
generally, percentiles) are not in many software packages is
because they can be computationally expensive to compute.
The only way I know how to generate percentiles is to first sort
the data into numeric order, and then select the appropriate value
from the list. Sorting is expensive, especially when there are a
lot of data. Is there a better/faster way of computing percentiles?
Tim Hume
Centre for Australian Weather and Climate Research
Melbourne
Australia
-----Original Message-----
From: Gerry Creager [mailto:gerry.creager@xxxxxxxx]
Sent: Monday, 12 May 2008 12:41
To: Timothy Hume
Cc: Dennis Shea
Subject: Re: [netcdfgroup] Calculating medians, quartiles etc of a
variable in a NetCDF file.
I'd consider looking at the NCAR command language and seeing if
quartile
calculation is native therein. I'd be surprised if it's not, or
easily
computable, but I did not find it initially.
Check http://www.ncl.ucar.edu/ and consider joining the mailing list
long enough to find out.
Timothy Hume wrote:
Hi,
I have an application where I would like to calculate quartiles of
a variable in a NetCDF file (I am computing the trimean: TM = 0.25*
(Q1 + 2Q2 + Q3) )
The NetCDF operators are excellent for computing arithmetic means,
but don't include the capability to compute quartiles. Before I
start writing my own code to compute quartiles, does anyone know
of some software which already does this? Basically, I am looking
for the equivalent of ncwa with a quartile operation.
Thanks,
Tim Hume
Centre for Australian Weather and Climate Research
Melbourne
Australia
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--
Gerry Creager -- gerry.creager@xxxxxxxx
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983
Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX
77843
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**********************
"The contents of this message do not reflect any position of the U.S.
Government or NOAA."
**********************
Roy Mendelssohn
Supervisory Operations Research Analyst
NOAA/NMFS
Environmental Research Division
Southwest Fisheries Science Center
1352 Lighthouse Avenue
Pacific Grove, CA 93950-2097
e-mail: Roy.Mendelssohn@xxxxxxxx (Note new e-mail address)
voice: (831)-648-9029
fax: (831)-648-8440
www: http://www.pfeg.noaa.gov/
"Old age and treachery will overcome youth and skill."
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For list information or to unsubscribe, visit: http://
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**********************
"The contents of this message do not reflect any position of the U.S.
Government or NOAA."
**********************
Roy Mendelssohn
Supervisory Operations Research Analyst
NOAA/NMFS
Environmental Research Division
Southwest Fisheries Science Center
1352 Lighthouse Avenue
Pacific Grove, CA 93950-2097
e-mail: Roy.Mendelssohn@xxxxxxxx (Note new e-mail address)
voice: (831)-648-9029
fax: (831)-648-8440
www: http://www.pfeg.noaa.gov/
"Old age and treachery will overcome youth and skill."
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