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Re: [ferret_users] Irregular Grid data Plot on ferret?



Hi,
Ferret's 3-argument shade and fill commands will work if the variables can be placed on a 2-D grid in index space, so that lon(i,j), lat(i,j) and var(i,j) are all defined for i=1:m and j=1:n.  If such an underlying grid makes sense for your data, then you will need to define axes (just DEFINE AXIS/X=1:100:1 and so forth with no units) and then define a grid and use that to read in the data.

If the grid cannot be represented that way, you might be able to visualize the data using a polygon command.  See the polymark.jnl script for more about how to do this

yes? go/help polymark.jnl

It would go something like this

file/var=lon,lat,tmp test.dat
go basemap x=120:250 Y=25s:65n 20   ! some region including the longitude,latitude locations

go polymark polygon/over/palette= /title=  lon, lat, tmp, square, 0.5

You can specify different shapes and experiment to get a good size polygon to show the data. 


Yu, Hao-Cheng wrote:
Hi Steve

Thanks for your reply.
But my problem is not Lack of basemap.
My question is:
Is Ferret can do plot(shade, or vector) with an irregular gridded data(from finite element model) without Object Analysis.
Such dataset won't have 2-D definition for variables, usually only 1-D definition.
Like

           I        J       K     L
Lat     1:10     :        :      :
Lon    1:10     :        :      :
Var    1:10     :        :      :

Variables location are defined as an irregular grid (Lat, Lon).
However, Ferret only do "shade" or "vector" plot for 2-D variables.

Any comments or suggestions?

Sincerely, dan


2007/4/26, Steve Guimond <guimond@xxxxxxxxxxxxxxxxx>:
Hi,
  Try laying down a basemap first, then using the shade command.

go basemap x=...

=======================================================
Stephen R. Guimond
Graduate Research Assistant
Center for Ocean-Atmospheric Prediction Studies (COAPS)
=======================================================

On Thu, 26 Apr 2007, Yu, Hao-Cheng wrote:

> Dear ferreters,
>
> I know Ferret can deal with grided data (for finite difference method) and
> it always works perfectly.
> However, after searching on the mail archives and UserGuide.
> Irregular dataset(like finite element method) seems only can be plotted by
> Regriding process(like objective analysis).
> I try with "3-arguments shade (even vector)", and Ferret tells if the
> dataset is not define as 2D, this won't work.
>
> file/var=lon,lat,tmp test.dat
> shade tmp,lon,lat
>
> test.dat contains 3 columns data which define each element node location and
> the property to plot (shade).
> Is it possible to "shade" or "vector" on irregular grid?
>
> Sincerely, Dan
>
>
>




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Ansley Manke, NOAA/PMEL   ansley.b.manke@xxxxxxxx
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