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Re: change Origin of Axes



Because the data set is just a 512*512 matrix(and we have the lat-lon position description for each point value also), a simple way to change the origin of Axes is using YLIMITS=hi:lo instead of YLIMITS=lo:hi in SHADE command for this data set.
As for differentiating the Missing values and Fill Values(secondary invalid values) in one file, we just sacrifice this, and contour the lat and lon lines to mark the user interested  region(it is north or south hemisphere in this scenario).

It seems we could specify TWO invalid values( one by Missing, another by _Fill) in Ferret User Guide, can we?
If the answer is YES, can we draw it in different colors?


Thanks,
Frank

Ansley Manke wrote:

> Hi Frank,
> Did you get a satisfactory solution to your questions?  If so could
> you post the answer back to the Ferret Users's list, so there is
> a resolution there which others might find?
>
> Ansley
>
> Yunyao Qu wrote:
>
> > Hi, Mick,
> >
> > Sorry for not clear declaring. The coordinate is NOT REAL lat-lon representation. It is a virtual 512x512 matrix
> > dimension.
> > I attached  2 sample files you can see its dimensiont.
> > I tested  (SHADE var x_page y_page, mp_....,etc) ,  they work fine in lat-lon gridded data. But this kind of  virtual
> > COL and ROW data ....
> >
> > Thanks
> > Frank QU
> >
> > Mick Spillane wrote:
> >
> > > Hi Frank,
> > >         Judging from your figure, which I take it is basically an
> > > mp_stereographic_north projection of your data, it is just the
> > > longitude that is flipped - I can see that Africa is backward but
> > > the north pole is where it ought to be.
> > >         The Ferret commands you give are not the ones that made this
> > > plot, at least not in my limited understanding of the mp_* demos.
> > > In the commands for making a polar stereographic plot in my demo
> > > below you will see the variable x_page that holds the "x" part of
> > > the transformation. The simplest way for you to fix your problem
> > > may be to replace x_page by (-1)*x_page in your shade command(s).
> > > There is also a variable "MP_CENTRAL_MERIDIAN" that you may choose
> > > to use to put a different meridian at 12 o'clock.
> > >
> > > My demo:
> > >
> > > ! flipping longitudes in a polar stereographic plot
> > >
> > > use etopo60
> > > set grid rose
> > >
> > > set win/aspect=1:ax
> > > ppl axset,0,0,0,0 ; ppl axlabp,0,0
> > >
> > > go mp_stereographic_north
> > > region/x=0:360/y=0:90
> > >
> > > ! first shade in the normal way (longitude is correct here)
> > >
> > > shade/nolab/nokey rose, x_page, y_page
> > >
> > > ! then flip/"correct" longitudes and use new MP_CENTRAL_MERIDIAN
> > >
> > > message
> > >
> > > let MP_CENTRAL_MERIDIAN=45
> > > shade/nolab/nokey rose, (-1)*x_page, y_page
> > >
> > > |--****--****-*---*---***--***--|____spillane@pmel.noaa.gov____|
> > > |-*__---*-----*--*-*--*--*-*--*-|_SCIENCE APPLICATIONS SUPPORT_|
> > > |--***--*-----*-*---*-***--***--|____EPIC/Ferret/PlotPlus______|
> > > |-----*-*-----*-*****-*----*----|__Room 2070 Bldg#3 NOAA/PMEL__|
> > > |-****---****-*-*---*-*----*----|____Phone_:_(206)526-6780_____|
> > >
> > > On Thu, 17 Jan 2002, Yunyao Qu wrote:
> > >
> > > > Hi, Mick,
> > > > My problem is EXACTLY as what you said:"....that when you plot it the "map"
> > > > is upsidedown....".
> > > > So, We would like to change it back when plot it.
> > > > The data set is simply  a (row, col) matrix NetCDF file.
> > > >
> > > > The following is script
> > > > ================
> > > > USE SAA_Descriptor
> > > > SET REGION/Y=90:0/X=180:-180/T=280683
> > > > SHADE/LEVELS=1/nokey/noaxis water_vapor //  get label
> > > > shade/LEVELS=1/nolab/nokey/noaxis/over/pal=black missing(water_vapor,0) //
> > > > plot missing data
> > > > SHADE/NOAXES/LEVELS=23/over/key/nolab water_vapor // plot image
> > > > shade/over/nolab/pal=grey/noaxis/lev=(0) water_vapor // plot special bad data
> > > >
> > > > ==================
> > > > The generated  image also attached. We would like its upside down.
> > > > http://wwwdev.saa.noaa.gov/VisData/EDRMAPNH14/GIF/2001_12_31-20:00:00-EDRMAPNH14-water_vapor-1_512_1_512-0.5.GIF
> > > >
> > > > Thanks,
> > > > Frank
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Mick Spillane wrote:
> > > >
> > > > > Hi Frank,
> > > > >         Its not quite clear to me what problem you are dealing with.
> > > > > Sometimes an xy dataset is ordered opposite to the Ferret norm of
> > > > > south to north/west to east so that when you plot it the "map" is
> > > > > upsidedown.
> > > > >         In some cases it is possible to orient the plot in the way
> > > > > desired using the ppl xaxis and ppl yaxis commands; in other cases
> > > > > one has to be more tricky.
> > > > >         I suggest you first take a look at the user group mail
> > > > > archives
> > > > >
> > > > > http://ferret.wrc.noaa.gov/Ferret/Mail_Archives/ferret_mail_archives.html
> > > > >
> > > > > where for example in 2001 you will find at least two notes that may
> > > > > deal with a situation like yours:
> > > > > http://ferret.wrc.noaa.gov/Ferret/Mail_Archives/fu_2001/msg00649.html
> > > > > http://ferret.wrc.noaa.gov/Ferret/Mail_Archives/fu_2001/msg00650.html
> > > > >
> > > > >         In general it may be useful to be more specific in your query -
> > > > > for example describe the format of your dataset, cut and paste lines
> > > > > from your ferret session that show how you accessed the data and plotted
> > > > > it, etc.
> > > > >
> > > > > Mick
> > > > >
> > > > > |--****--****-*---*---***--***--|____spillane@pmel.noaa.gov____|
> > > > > |-*__---*-----*--*-*--*--*-*--*-|_SCIENCE APPLICATIONS SUPPORT_|
> > > > > |--***--*-----*-*---*-***--***--|____EPIC/Ferret/PlotPlus______|
> > > > > |-----*-*-----*-*****-*----*----|__Room 2070 Bldg#3 NOAA/PMEL__|
> > > > > |-****---****-*-*---*-*----*----|____Phone_:_(206)526-6780_____|
> > > >
> > > > --
> > > > Yunyao "Frank" Qu
> > > > Satellite Active Archive (SAA)
> > > > NESDIS, NOAA
> > > >
> > > >
> >
> > --
> > Yunyao "Frank" Qu
> > Satellite Active Archive (SAA)
> > NESDIS, NOAA
> >
> >   ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> >                                  Name: 20011231_200000.cdf
> >    20011231_200000.cdf           Type: Channel File (application/x-cdf)
> >                              Encoding: base64
> >                       Download Status: Not downloaded with message
>
> --
> Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246

--
Yunyao "Frank" Qu
Satellite Active Archive (SAA)
NESDIS, NOAA





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