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

["Yu, Hao-Cheng" <danish.url@xxxxxxxxx>]

Thanks for your quick reply

Such method Only plot the node value, can't really do "fill" plot (interpolation between nodes).
And,  "vector" seems can't be plotted on such grid system.  
Is Objective Analysis the only way to treat such data?
Or change another plotting package? (That will be sad, I use Ferret for a very long time.)

Dan

2007/4/26, Ansley Manke < Ansley.B.Manke@xxxxxxxx>:

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
7600 Sand Point Way NE, Seattle WA
Phone 206-526-6246,  FAX 206-526-6744