RE: [ncl-talk] coordinate subscripting

From: Marjolaine Krug (marjolaine AT XXXXXX)
Date: Mon Dec 06 2004 - 23:57:43 MST

  • Next message: Dennis Shea: "Re: Indecipherable error message"

    Hi,

    lonFlip worked. Thanks for your help.

    Rgs, Marjolaine.

    -----Original Message-----
    From: Dennis Shea [mailto:shea AT cgd.ucar.edu]
    Sent: Tuesday, December 07, 2004 12:44 AM
    To: marjolaine AT absamail.co.za
    Subject: RE: [ncl-talk] coordinate subscripting

    As Sylvia indicates use "lonFlip"

       f = addfile (...)
       x = f->Some_Variable ; coords o->360
       x = lonFlip(x) ; coords -180->180

    You could also do the following:
       x = lonFlip( f->Some_Variable ) ; coords -180->180

    then something like

       latS = -75
       latN = 30
       lonL = -40
       lonR = 20

       X = x(:,{latS:latN},{lonL:lonR})

    good luck
    D

    >
    >Thanks, I will look into it.
    >
    >Best regards, Marjolaine.
    >
    >-----Original Message-----
    >From: Sylvia Murphy [mailto:murphys AT cgd.ucar.edu]
    >Sent: Wednesday, December 01, 2004 7:45 PM
    >To: Marjolaine Krug
    >Cc: NCL talk
    >Subject: RE: [ncl-talk] coordinate subscripting
    >
    >
    >M,
    >
    >by definition, a coordinate variable must be either monotonically
    >increasing or decreasing. this is a requirement of netCDF. Is your
    >longitude actually attached?
    >
    >if the problem is the resultant extraction not being monotonic, then you
    >may want to check out the lonFlip function in contributed.ncl which will
    >change a 0-360 coordinate to -180 to 180 and vice versa.
    >
    >sm
    >
    >
    >On Wed, 1 Dec 2004, Marjolaine Krug wrote:
    >
    >> Dear Sylvia,
    >>
    >> The domain I want in my data is from 40West to 20East, which correspond
    to
    >> points from :
    >> 320 to 360
    >> and
    >> 360 (i.e 0) to 20
    >> The problem is that my data longitude is not monotonic. So I can't just
    >> extract the domain I want. I suppose I could extract both arrays
    >> y1 = x({320:360},{minLat:maxLat}) and
    >> y2 = x({0:20},{minLat:maxLat}) and then concatenate y1 and y2 into a
    >> variable y. Only thing is that I am not sure how to concatenate y1 and
    y2.
    >>
    >> Regards, Marjolaine.
    >>
    >> -----Original Message-----
    >> From: Sylvia Murphy [mailto:murphys AT cgd.ucar.edu]
    >> Sent: Monday, November 29, 2004 6:03 PM
    >> To: Marjolaine Rouault
    >> Cc: ncl-talk AT ucar.edu
    >> Subject: Re: coordinate subscripting
    >>
    >>
    >> M,
    >>
    >> you certainly can use coordinate subscripting. This method is dependent
    >> upon what your coordinates look like. if your coordinates go from -180 to
    >> +180 then you need to use those values while coordinate subscripting. if,
    >> as in your case, they go from 0 to 360 you need to use those values.
    >>
    >> for example
    >>
    >> y = x({-20:20},{270:360})
    >>
    >> in your case you need to mentally convert the region you want into
    >> 360-mode and then subscript.
    >>
    >> sylvia
    >>
    >>
    >>
    >> On Mon, 29 Nov 2004, Marjolaine Rouault wrote:
    >>
    >> > Hi,
    >> >
    >> > I am reading some data which longitude is not "ordered" in the usual
    >way.
    >> >
    >> > Longitude points from 0 east to 180 east have a longitude which
    >increases
    >> from 0 to 180.
    >> > Longitude points from 180 west to 0 west have a longitude value which
    >> increases from 181 to 360.
    >> >
    >> > I am trying to extract a domain between 40West and 20 East.Is it
    >possible
    >> to do it with coordinate subscripting? What would you suggest is the best
    >> way to extract my domain?
    >> >
    >> > Many thanks, Marjolaine.
    >> >
    >> >
    >> >
    >> > _______________________________________________
    >> > ncl-talk mailing list
    >> > ncl-talk AT ucar.edu
    >> > http://mailman.ucar.edu/mailman/listinfo/ncl-talk
    >> >
    >>
    >>
    >>
    >> ******************************************************
    >> Sylvia Murphy EML: murphys AT ucar.edu
    >> NCAR CGD/CSEG PHN: 303-497-1720
    >> 1850 Table Mesa Drive FAX: 303-497-1333
    >> Boulder CO 80305
    >>
    >>
    >> WEB: http://www.cgd.ucar.edu/csm/support/
    >> http://www.cgd.ucar.edu/csm/support/CSM_Graphics/
    >> ******************************************************
    >>
    >>
    >>
    >> _______________________________________________
    >> ncl-talk mailing list
    >> ncl-talk AT ucar.edu
    >> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
    >>
    >
    >
    >
    >******************************************************
    >Sylvia Murphy EML: murphys AT ucar.edu
    >NCAR CGD/CSEG PHN: 303-497-1720
    >1850 Table Mesa Drive FAX: 303-497-1333
    >Boulder CO 80305
    >
    >
    >WEB: http://www.cgd.ucar.edu/csm/support/
    > http://www.cgd.ucar.edu/csm/support/CSM_Graphics/
    >******************************************************
    >
    >
    >
    >_______________________________________________
    >ncl-talk mailing list
    >ncl-talk AT ucar.edu
    >http://mailman.ucar.edu/mailman/listinfo/ncl-talk

    _______________________________________________
    ncl-talk mailing list
    ncl-talk AT ucar.edu
    http://mailman.ucar.edu/mailman/listinfo/ncl-talk

    This archive was generated by hypermail 2b29 : Tue Dec 07 2004 - 09:01:21 MST