[ncl-talk] mean value of all displayed grid points / pixel in a map

Dennis Shea shea at ucar.edu
Mon Sep 1 08:13:16 MDT 2014


As previously noted:

For a rectilinear grid: wgt_areaave_Wrap calculates an area average
https://www.ncl.ucar.edu/Document/Functions/Contributed/wgt_areaave_Wrap.shtml

For a curvilinear grid:
http://www.ncl.ucar.edu/Document/Functions/Built-in/wgt_areaave2.shtml

or a simple arithmetic average: avg

http://www.ncl.ucar.edu/Document/Functions/Built-in/avg.shtml





On Mon, Sep 1, 2014 at 7:57 AM, Kreienkamp Frank <Frank.Kreienkamp at dwd.de>
wrote:

>  Hello Dennis,
>
>
>
> sorry that my question wasn’t clear enough.
>
>
>
> Let my try again.
>
> The attached map is a displayed result of RCM-dataset. The original grid
> covers Europe. The displayed area covers Germany and a bit more.
>
>
>
> What I am looking for is a routine that calculates the mean value of the
> displayed area.
>
>
>
> Thanks in advance
>
> Frank
>
>
>
> *Von:* ncl-talk-bounces at ucar.edu [mailto:ncl-talk-bounces at ucar.edu] *Im
> Auftrag von *Dennis Shea
> *Gesendet:* Montag, 1. September 2014 15:11
> *An:* Kreienkamp Frank
> *Cc:* ncl-talk
> *Betreff:* Re: [ncl-talk] mean value of all displayed grid points / pixel
> in a map
>
>
>
> The question is vague
>
> "I want to calculate the mean value of all displayed grid points in a map.
>
> This means:
> - i have gridded data for the entire world (gcm-results)
> - i plot a map (stereographic projection) for Europe
>
> NCL draws a rectangle map based on the given resource parameters. I am
> looking for a function which counts all displayed values (pixel?) and
> calculates an average value."
>
> NCL handles "gridded data for the entire world (gcm-results)" all the time.
>
>
>
> [1]  dim_avg_n_Wrap will calculate the means at each grid point over all
> times.
>
> [2] wgt_areaave_Wrap calculates an area average
>
> [3] NCL can display much more than a "rectangular map"
>
> [4] wks = gsn_open_wks("png" ,"frank")
>
>      will send graphics to a png file
>
> What do you mean by:
>
> "Is there a chance that i can get the matrix-values which are send to the
> (png-)workstation?"
>
>
> =======
>
> https://www.ncl.ucar.edu/Document/Functions/Contributed/dim_avg_n_Wrap.shtml
> https://www.ncl.ucar.edu/Applications/climo.shtml
>
> https://www.ncl.ucar.edu/Document/Functions/Contributed/wgt_areaave_Wrap.shtml
> https://www.ncl.ucar.edu/Applications/maponly.shtml
>
> https://www.ncl.ucar.edu/Document/Graphics/Interfaces/gsn_csm_contour_map.shtml
>
> Good luck
>
>
>
> On Mon, Sep 1, 2014 at 2:31 AM, Kreienkamp Frank <Frank.Kreienkamp at dwd.de>
> wrote:
>
> Hello ,
>
> since having no one answering the original question.
>
> Is there a chance that i can get the matrix-values which are send to the
> (png-)workstation?
>
> Thanks in advance
> Frank Kreienkamp
>
> -----Ursprüngliche Nachricht-----
> Von: ncl-talk-bounces at ucar.edu [mailto:ncl-talk-bounces at ucar.edu] Im
> Auftrag von Frank Kreienkamp
> Gesendet: Mittwoch, 27. August 2014 06:37
> An: ncl-talk
> Betreff: [ncl-talk] mean value of all displayed grid points / pixel in a
> map
>
>
> Hello,
>
> i have searched the function list but i have not found a solution for the
> following problem.
>
> I want to calculate the mean value of all displayed grid points in a map.
>
> This means:
> - i have gridded data for the entire world (gcm-results)
> - i plot a map (stereographic projection) for Europe
>
> NCL draws a rectangle map based on the given resource parameters. I am
> looking for a function which counts all displayed values (pixel?) and
> calculates an average value.
>
> Thanks in advance
> Frank
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