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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 avariable 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 _______________________________________________ netcdfgroup mailing list netcdfgroup@xxxxxxxxxxxxxxxx For list information or to unsubscribe, visit: http:// www.unidata.ucar.edu/mailing_lists/-- Gerry Creager -- gerry.creager@xxxxxxxxTexas Mesonet -- AATLT, Texas A&M University Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843_______________________________________________ netcdfgroup mailing list netcdfgroup@xxxxxxxxxxxxxxxx For list information or to unsubscribe, visit: http:// www.unidata.ucar.edu/mailing_lists/********************** "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." _______________________________________________ netcdfgroup mailing list netcdfgroup@xxxxxxxxxxxxxxxxFor list information or to unsubscribe, visit: http:// www.unidata.ucar.edu/mailing_lists/
**********************"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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