[ncl-talk] extract_Data_from_polygon

[Kunal Bali]

Dear Guido


The ASCII output from this script is not showing the whole data of the
selected box and the values are also repeating in the ASCII file.

Anyways, Thank You so much for your time. I appreciate that.

Thank You


Kunal Bali
Research Scholar
Radio & Atmospheric Science Division
CSIR - National Physical Laboratory
New Delhi - 110012
India





On Fri, May 27, 2016 at 10:19 PM, Guido Cioni <guidocioni at gmail.com> wrote:

> Dear Kunal,
> attached you find the resulting script. First I subsetted the var over the
> domain that you specified (the one that is used to plot the polygon) and
> obtain var2. Then I did some trick to get the lat/lon coordinates printed
> in the CSV file.
>
>
>
>
> Guido Cioni
> http://guidocioni.altervista.org
>
>
>
>
> Il giorno 27 mag 2016, alle ore 17:51, Kunal Bali <kunal.bali9 at gmail.com>
> ha scritto:
>
> I am not getting it exactly how to do this one.
> Could any one please help me out to do this.
>
> Kunal Bali
> Research Scholar
> Radio & Atmospheric Science Division
> CSIR - National Physical Laboratory
> New Delhi - 110012
> India
>
>
>
>
>
> On Fri, May 27, 2016 at 6:12 PM, Guido Cioni <guidocioni at gmail.com> wrote:
>
>> Once you have the correct variable you can write it to an CSV file by
>> using the write table function.
>>
>>  alist=[/clon,clat,var2/]
>>  write_table(“file.csv”,"w",alist,”%f,%f,%f,%f")
>>
>> Guido Cioni
>> http://guidocioni.altervista.org
>>
>> On 27 May 2016, at 14:24, Kunal Bali <kunal.bali9 at gmail.com> wrote:
>>
>> Dear Guido
>>
>> Thanks for the information.
>> Actually, I need to extract the data as ASCII or CSV file of the selected
>> polygon box
>>
>>
>>
>> Kunal Bali
>> Research Scholar
>> Radio & Atmospheric Science Division
>> CSIR - National Physical Laboratory
>> New Delhi - 110012
>> India
>>
>>
>>
>>
>>
>> On Fri, May 27, 2016 at 5:35 PM, Guido Cioni <guidocioni at gmail.com>
>> wrote:
>>
>>> Dear Kunal,
>>> I didn’t answer to the first email because I am not really familiar with
>>> shapefile and masking over nations boundaries, but I guess there is a
>>> lot of documentation on the website. Is your a polygon just an
>>> approximation because you don’t know how to mask using the shape file or is
>>> it really what you wanted to do?
>>>
>>> In order to extract the data you can either create a new variable where
>>> you mask the region outside of the polygon or where you put all the data
>>> inside of the polygon. I would use the first approach, since what you get
>>> is a variable with the same dimensions, but maybe the second one is easier.
>>> Since you have two arrays with lon,lat coordinates can’t you just
>>> create a new variable, called var2, which is a subset of var?
>>>
>>> Assuming that var has dimension (time, lat, lon) you can simply do that
>>>
>>> var2=var(:,{lat},{lon})
>>>
>>> The {} means that you are using coordinate indexing, it should work
>>> also with array although I’m not 100% sure. With this method you will get a
>>> variable with different dimensions. Otherwise you can try to mask using
>>> logical staments. Assuming you have (clon,clat) coordinates in your
>>> file (I used different names because of your definition in the script) you
>>> can try something similar
>>>
>>> var2=mask(var, lon.ge.min(clon) .AND. lon.le.max(clon) .AND.
>>> lat.ge.min(clat) .AND. lat.le.max(clat), False)
>>>
>>> Cheers
>>>
>>>
>>> Guido Cioni
>>> http://guidocioni.altervista.org
>>>
>>> On 27 May 2016, at 12:31, Kunal Bali <kunal.bali9 at gmail.com> wrote:
>>>
>>> Dear NCL
>>>
>>> I tried to make the  polygon of the selected region. I don't know i did
>>> it correctly or not, please let me know is it correct way to do or not.
>>>
>>> Second thig is that I need to extract the data from selected polygon.
>>> Could anyone please let me know how to do it ?
>>>
>>>
>>> Regards
>>> Kunal Bali
>>>
>>>
>>>
>>>
>>>
>>> <polygon.ncl><polygon.png>
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>>>
>>
>>
> <FRP.nc>
>
>
>
>
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