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

[Kreienkamp Frank]

Hello Dennis,

if i read the webpage correctly the suggested functions are not what i am looking for.

Yes, I am looking for an areal average.

No, it is not for an rectangular grid.

I have an rectangular grid as the ‘base’. Using this grid and a polar stereographic projection I am drawing a map. This map is showing  only a part of the hole ‘base’ grid. I am looking for an average of this shown/drawn part.

Writing the same from a different view. I am looking for a function what calculates the average values of the presented map. See the example in my previous e-mail.

As far a I understand the description correctly this in not what the function wgt_areaave_wrap provides.

Thanks in advance
Frank

Von: Dennis Shea [mailto:shea at ucar.edu]
Gesendet: Montag, 1. September 2014 16:13
An: Kreienkamp Frank
Cc: ncl-talk
Betreff: Re: [ncl-talk] mean value of all displayed grid points / pixel in a map

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<mailto: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> [mailto: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<mailto: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> [mailto: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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