Re: [ferret_users] weird contour

[Patrick McGuire <mcguire@xxxxxxxxxxxxxxxxxxx>]

thank you, Ansley!!

Yes, I am trying to use these curvilinear grids. (sorry for calling them 
as irregular grids).

It looks like I need to make the xb grid be 2D instead of 1D.
I just tried to do this, with this script:

  let xb=x[x=0:290:10]
  let yb=y[y=0:290:10]
  let yb1= if (yb1 GT -1) then 1 else 0
  let xb2=xb*yb1 !this makes a 2D array with all the rows the same; is
                 !     there an easier way to do this??
  let zb=I[x=0:290:10]*J[y=0:290:10]
  contour/hlimits=-100:400:50 xb2+zb,xb2,zb

But even with both xb2 and zb being two-dimensional, I get the same 
problems with contour. I will keep studying this problem. But can you 
advise further?

PM
---------------------------------------------
http://geosci.uchicago.edu/~mcguire/
---------------------------------------------
Department of the Geophysical Sciences
University of Chicago

On Thu, 17 Sep 2009, Ansley Manke wrote:

> hi Patrick -
> What Ferret calls an irregular grid, is just an irregularly-spaced 
> rectangular grid.
>
> We have graphics commands for data on "Curvilinear grids" - 
> http://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/working-with-special-data-sets/CURVILINEAR-COORDINATE-DATA
> In that section is the definition:
>
>   A curvilinear grid has longitudes and latitudes defined by
>   coordinates (lon[i, j],lat[i, j]) in 2D, and the data fields are
>   also defined on the [i,j] index grid. ...
>
> And the details of graphical commands for these grid types is at
> http://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/customizing-plots/MAP-PROJECTIONS-AND-CURVILINEAR-COORDINATES#_VPINDEXENTRY_876
>
> Ansley
>
> Patrick McGuire wrote:
> > But can't the contour command use irregular grids?
> > zb is an example of an irregular grid.
> >
> > PM
> > ---------------------------------------------
> > http://geosci.uchicago.edu/~mcguire/
> > ---------------------------------------------
> > Department of the Geophysical Sciences
> > University of Chicago
> >
> > On Thu, 17 Sep 2009, Ansley Manke wrote:
> >
> > > Hi Patrick,
> > > I'm confused by your example. The variables  zb  and (xb+zb) are 
> > > 2-dimensional arrays, 30x30, but xb is 1-d.  The 3-argument contour 
> > > command expects all arguments to be 2-D arrays.
> > >
> > > Ansley
> > >
> > >
> > > Patrick McGuire wrote:
> > > > Hi Ferret Users
> > > >    I've been having some problems with ferret recently.
> > > >
> > > >    The example below demonstrates the problem. I can give more examples 
> > > > if you wish. But this problem affects ALL of my FERRET plots for the 
> > > > methane-hydrate model spongebob, where I plot data from a netcdf file.
> > > >
> > > > FERRET EXAMPLE:
> > > >  let xb=x[x=0:290:10]
> > > >  let zb=I[x=0:290:10]*J[y=0:290:10]
> > > >  contour/hlimits=-100:400:50 xb+zb,xb,zb
> > > >
> > > >   The problem seems to be when I use an irregular zb grid, sometimes when 
> > > > I do contour or fill, the plot has really weird and large jumps in the x 
> > > > direction of the contours. We're using ferret 6.2.
> > > >
> > > >    Do you have any insights? I have attached a screenshot if you don't 
> > > > see the problem when you run these commands yourself. If you don't see it 
> > > > on your end, you might try changing the commands slightly to see if you 
> > > > can see similar problems. But this has been reproduced by other ferret 
> > > > 6.2 users.
> > > >
> > > > PM
> > > > ---------------------------------------------
> > > > http://geosci.uchicago.edu/~mcguire/
> > > > ---------------------------------------------
> > > > Department of the Geophysical Sciences
> > > > University of Chicago
> > > >
> > > > ------------------------------------------------------------------------