[ncl-talk] convert polyline shapefile to netcdf via ncl_convert2nc

[Lyndz]

Hi Sir Dennis,

I tried your suggestion. I was able to run the script but I'm getting a
very large count. When I counted it manually, the count does not exceed 10.
But I'm getting around 88.
Attached are the output image, csv input file, and modified script.

I only wanted to count the TC with Vmax greater than 35knts. So I tried
masking first the data.

I might be missing one important step here.

Many thanks for the help.

Sincerely,

Lyndz


On Mon, Apr 9, 2018 at 3:17 AM, Dennis Shea <shea at ucar.edu> wrote:

> http://www.ncl.ucar.edu/Applications/binning.shtml
>
> See Example 2:
>
>   freq  = count
>   freq  = (count/npts)*100   ; comment this
>
>
> On Sat, Apr 7, 2018 at 9:05 PM, Lyndz <olagueralyndonmark429 at gmail.com>
> wrote:
>
>> Hi Sir Rick,
>>
>> Thank you for the fast response.
>> I wanted to create a 5degree by 5degree grid NetCDF file from the
>> shapefile, where each grid box contains the "count"(frequency) of unique TC
>> tracks per category.
>> I'm just wondering if this is possible to do in NCL.
>>
>> Sincerely,
>>
>> Lyndz
>>
>>
>> On Sun, Apr 8, 2018 at 3:34 AM, Rick Brownrigg <brownrig at ucar.edu> wrote:
>>
>>> Hi Lyndz,
>>>
>>> I'm not sure there is a "correct" way to do this. NetCDF is really good
>>> at representing regular arrays of data, whereas polylines/polygons tend to
>>> have varying numbers of coordinate pairs -- what would lat and lon
>>> variables look like in that case, and what would be the meaning of lat/lon
>>> dimensions?  NCL makes a shapefile *look* like a NetCDF file by packing the
>>> coordinate information for all features into the x/y variables, but then
>>> one has to utilize the geometry and segments variables to unpack
>>> coordinates for each feature. The shapefiles examples page show many
>>> examples of doing this:
>>>
>>>     http://ncl.ucar.edu/Applications/shapefiles.shtml
>>>
>>> If you are working with NCL, you are probably better off leaving your
>>> data as a shapefile*. *I take it however that you have other reasons
>>> for wanting a NetCDF file?
>>>
>>> Finally, I might comment that the conversion result may not be correct
>>> -- its suspect to me that the "num_points" value is exactly twice the value
>>> of "num_features" -- I wonder if maybe just the end-points of the tracks
>>> where what got captured in the conversion?
>>>
>>> Rick
>>>
>>> On Fri, Apr 6, 2018 at 11:30 PM, Lyndz <olagueralyndonmark429 at gmail.com>
>>> wrote:
>>>
>>>> Dear NCL experts,
>>>>
>>>> I would like to convert the following shapefile to a netcdf file.
>>>> I created the shapefile from a csv file containing jtwc tc tracks (see
>>>> attached csv2shp.py)
>>>> Also attached is the csv file.
>>>>
>>>> When I used the ncl_convert2nc the netcdf file has no lat-lon
>>>> dimension. Here's the output of the ncdump. Is it also possible to divide
>>>> the TC categories by dividing the Vmax values?
>>>>
>>>>
>>>> I'll appreciate any suggestion on how to do this correctly.
>>>>
>>>>
>>>> netcdf par_jtwc_above_ts_1979-1993 {
>>>> dimensions:
>>>> geometry = 2 ;
>>>> segments = 2 ;
>>>> num_features = 1050 ;
>>>> num_segments = 1050 ;
>>>> num_points = 2100 ;
>>>> variables:
>>>> int geometry(num_features, geometry) ;
>>>> int segments(num_segments, segments) ;
>>>> double x(num_points) ;
>>>> double y(num_points) ;
>>>> int SN(num_features) ;
>>>> int CY(num_features) ;
>>>> int Y1(num_features) ;
>>>> int M1(num_features) ;
>>>> int D1(num_features) ;
>>>> int H1(num_features) ;
>>>> int VMax1(num_features) ;
>>>> int Y2(num_features) ;
>>>> int M2(num_features) ;
>>>> int D2(num_features) ;
>>>> int H2(num_features) ;
>>>> int VMax2(num_features) ;
>>>>
>>>> // global attributes:
>>>> :segs_numPnts = 1 ;
>>>> :segs_xyzIndex = 0 ;
>>>> :geom_numSegs = 1 ;
>>>> :geom_segIndex = 0 ;
>>>> :geometry_type = "polyline" ;
>>>> :layer_name = "par_jtwc_above_ts_1979-1993" ;
>>>> :creation_date = "Sat Apr  7 14:11:24 JST 2018" ;
>>>> :NCL_Version = "6.4.0" ;
>>>> :system = "Linux localhost.localdomain 3.10.0-327.36.3.el7.x86_64 #1
>>>> SMP Mon Oct 24 16:09:20 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux" ;
>>>> :Conventions = "None" ;
>>>> :title = "NCL: convert-OGR-to-netCDF" ;
>>>> }
>>>>
>>>>
>>>> Sincerely,
>>>>
>>>> Lyndz
>>>>
>>>>
>>>> _______________________________________________
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>>>> ncl-talk at ucar.edu
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>>>>
>>>>
>>>
>>
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