[ncl-talk] NCL plot problem with ascii data

[MM Ali]

Hello Dennis,

Thank you very much for your elaborate explanation and particularly for
correcting my manuscript. When I ran the edited code, I get the following
error:

fatal:Cannot create triangular mesh: supply additional resources or build
with Triangle package
fatal:ContourPlotDraw: draw error
fatal:ContourPlotDraw: draw error
fatal:PlotManagerDraw: error in plot draw
fatal:_NhlPlotManagerDraw: Draw error
fatal:Cannot create triangular mesh: supply additional resources or build
with Triangle package
fatal:ContourPlotDraw: draw error
fatal:ContourPlotDraw: draw error
fatal:PlotManagerDraw: error in plot draw
fatal:_NhlPlotManagerDraw: Draw error

Please suggest the changes in the code.

Best regards
Ali

On Fri, Apr 5, 2019 at 5:44 AM Dennis Shea <shea at ucar.edu> wrote:

> As ncl-talk always mentions: The 1st rule of data processing is: *Look at
> your data!*
>
> [1]
> The data look like they are sub-sampled from a gridded dataset. Given the
> distribution of the locations, I would call this a 'ragged-2d-array.'
> Specifically: each latitude  has a different number of points; each
> longitude has a different number of points. See plots.
>
> [2]
> Due to the ordering of the values on the ascii file, coordinate value
> syntax [ *&* ] should not be used. Specifically, the latitude and
> longitude values are not monotonic which is a requirement for coordinate
> arrays.
>
> [3]
> The the values are between 100E and 70W. For a limited region, I find is
> easier in this instance to use all positive longitudes [or all negative
> longitudes]. Hence, I changed a longitude range of 100 to 290.
>
> longitude = *where*
> <http://www.ncl.ucar.edu/Document/Functions/Built-in/where.shtml>(longitude.lt.0,
> longitude+360, longitude)
>
> [4]
>
> For graphics, NCL requires ragged arrays to be treated as an array of
> random locations [eg: station data].
>
>   res*@*sfXArray = longitude  ; data values are irregularly spaced
>   res*@*sfYArray  = latitude
>
> [5]
>
> The *gsn_coordinates* graphics utility which plot markers at each
> location requires that the 1d latitude/longitude be attributes to the
> variable being plotted:
>
>   variable*@lon1d*  = longitude
>   variable*@lat1d*   = latitude
> *  gsn_coordinates
> <http://www.ncl.ucar.edu/Document/Graphics/Interfaces/gsn_coordinates.shtml>*(wks,contour,variable,mkres)
>
>
> [6]
>
> The plots alternate between *cnFillMode*
> <http://www.ncl.ucar.edu/Document/Graphics/Resources/cn.shtml#cnFillMode>
> using the default  cnFillMode="AreaFill" and cnFillMode="RasterFill"
>
> In this case, I suggest cnFillMode="RasterFill"
>
> [7] For values that span 0.0, color palettes with *White-in-the-middle*
> <http://www.ncl.ucar.edu/Document/Graphics/color_table_gallery.shtml>
> work best
> ======
>
> *%> ncl*  MMali.ncl
>
> =====
>
> Good luck
>
>
> On Thu, Apr 4, 2019 at 10:06 AM Toni Klemm <toni-klemm at tamu.edu> wrote:
>
>> Hi Ali,
>>
>> I had this problem before. Since you extracted lat and lon data from
>> ASCII, it might be that your data doesn’t have metadata information
>> attached that tells NCL what it is (i.e., latitudes and longitudes).
>> Without that it is just a bunch of numbers for NCL. You can add this
>> metadata by adding this to your code after you extract your latitude and
>> longitude variables:
>>
>>   latitude!0 = "lat"
>>   latitude&lat = lat
>>   latitude at long_name = "latitude"
>>   latitude at units = "degrees_north"
>>
>>   longitude!0 = "lon"
>>   longitude&lon = lon
>>   longitude at long_name = "longitude"
>>   longitude at units = "degrees_east"
>>
>> Hope that helps,
>> Toni
>>
>>
>>
>> *Toni Klemm, Ph.D.*Postdoctoral Research Associate
>> Department of Ecosystem Science and Management
>> College of Agriculture and Life Sciences
>> Texas A&M University, College Station, TX
>> Contributor to the Early Career Climate Forum <http://www.eccforum.org>
>> www.toni-klemm.de | @toniklemm <http://twitter.com/toniklemm>
>>
>>
>>
>>
>>
>>
>>
>>
>> On Apr 4, 2019, at 2:00 AM, MM Ali <mmali110 at gmail.com> wrote:
>>
>> Hi,
>>
>> I modified the ce_3.ncl code to read the ascii data. Data and the
>> modified ncl code are attached. The variables in the data are dummy,
>> latitude, longitude, variable, dummy2. I get the following errors
>>
>> (0)     check_for_y_lat_coord: Warning: Data either does not contain
>> (0)     a valid latitude coordinate array or doesn't contain one at all.
>> (0)     A valid latitude coordinate array should have a 'units'
>> (0)     attribute equal to one of the following values:
>> (0)         'degrees_north' 'degrees-north' 'degree_north' 'degrees
>> north' 'degrees_N' 'Degrees_north' 'degree_N' 'degreeN' 'degreesN' 'deg
>> north'
>> (0)     check_for_lon_coord: Warning: Data either does not contain
>> (0)     a valid longitude coordinate array or doesn't contain one at all.
>> (0)     A valid longitude coordinate array should have a 'units'
>> (0)     attribute equal to one of the following values:
>> (0)         'degrees_east' 'degrees-east' 'degree_east' 'degrees east'
>> 'degrees_E' 'Degrees_east' 'degree_E' 'degreeE' 'degreesE' 'deg east'
>> (0)     Error: scalar_field: If the input data is 1-dimensional, you must
>> set sfXArray and sfYArray to 1-dimensional arrays of the same length.
>> warning:create: Bad HLU id passed to create, ignoring it
>>
>> Please help. It would be great if the necessary corrections are made to
>> the code (I am just a few days old for NCL, though 66+ years old!)
>> Thanks
>> Ali
>> *Dr. MM Ali*
>> Formerly:
>> Scientist G & Group Director
>> NRSC/ISRO
>> email: mmali110 at gmail.com
>>            mmali at coaps.fsu.edu
>> Mob: +91 9949045110
>> <may.txt><ce3.ncl>_______________________________________________
>> ncl-talk mailing list
>> ncl-talk at ucar.edu
>> List instructions, subscriber options, unsubscribe:
>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>
>>
>> _______________________________________________
>> ncl-talk mailing list
>> ncl-talk at ucar.edu
>> List instructions, subscriber options, unsubscribe:
>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>
>

-- 
*Dr. MM Ali*
Formerly:
Scientist G & Group Director
NRSC/ISRO
email: mmali110 at gmail.com
           mmali at coaps.fsu.edu
Mob: +91 9949045110
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20190405/1dc955d2/attachment.html>