[ncl-talk] problem in creating coordinate variable

[Mary Haley]

Ipsita,

If you have 3 columns of data, where each column has 360*720 values, then
you will need to read them in as an n x 3 array as you are already doing,
but then use the "reshape" function to reshape the arrays into 2D arrays of
360 x 720.

http://www.ncl.ucar.edu/Document/Functions/Built-in/reshape.shtml

Your information about the ASCII data file is too vague.

I don't know what latitude index 108 or longitude index 523 represents in
terms of actual degrees. Do you have a description of this file that tells
you?  This responsibility falls on you to know this, and write the script
accordingly, because NCL can't make any assumptions on what the actual
values are.

Also, is this a rectilinear grid or a curvilinear grid? If you indeed have
a 360 x 720 array of unique latitude values, and a 360 x 720 array of
longitude values, then this is a curvilinear grid, and hence you cannot use
coordinate arrays in the way you were trying to do so in your original
script.

Please, in the future, you must include more information about your data,
because otherwise it creates a lot of back and forth emails with us trying
to figure it out.

--Mary

On Wed, Nov 26, 2014 at 8:28 PM, Ipsita Putatunda <
ipsita.putatunda at gmail.com> wrote:

> The lat lon value 108 and 500 etc is giving the index of lat lon not the
> exact lat lon in degrees; there are actually 360 *720 lat lon points and
> for testing purpose I have selected a part of the file.
>
> I want to create a 2D variable say Var(lat,lon) where for each grid point
> there must be  a single value of the variable. But the ascii file contains
> lat, lon,var in three different column.
>
> Say for example the third row I want Var(lat,lon)=0.06 which should
> corresponds to the grid where lat=108 and lon=523.
> Hope I am able to make it clear what I want.
>
> Thanks,
> Ipsita
>
>
>
>
> On Wed, Nov 26, 2014 at 9:46 PM, Mary Haley <haley at ucar.edu> wrote:
>
>> Ipsita,
>>
>> You are creating an 18 x 18 2D array to hold your data, but you only have
>> a 1D array of 18 values.
>>
>> Also, I don't know what you mean by "2-dimensional coordinate variable".
>>
>> What you have is a collection of 18 random points, each with a lat/lon
>> point associated with it.  This cannot be represented by a 2D array with
>> lat/lon coordinate arrays.
>>
>> Also, the latitude values all have a value of "108", and the longitude
>> values are all greater than 500. Are you sure these values are actually
>> lat/lon?
>>
>> --Mary
>>
>>
>> On Wed, Nov 26, 2014 at 3:54 AM, Ipsita Putatunda <
>> ipsita.putatunda at gmail.com> wrote:
>>
>>> Dear NCL users,
>>>   I have an ASCII file (tt.txt) with data in 3 columns for latitude
>>> longitude and variable respectively. Am reading this data using asciiread
>>> and trying to create a 2 dimensional coordinate variable with  the same lat
>>> lon and variable values.But the output is giving all undefined values. Any
>>> help in this issues will be appreciated. My script is attached herewith.
>>>
>>> Thanks,
>>> Ipsita
>>>
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>>
>
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