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

[Dave Allured - NOAA Affiliate]

Oops, there is a bug in my print statement.  Change "lines" to "data":

       print (count(jl,il) + "  " + data(n))


On Mon, Apr 9, 2018 at 6:22 PM, Dave Allured - NOAA Affiliate <
dave.allured at noaa.gov> wrote:

> Lyndz,
>
> Try this to find the problem with your counting method.  Below this line:
>
>     valavg(jl,il) = valavg(jl,il) + cval(n)
>
> Add these code lines:
>
>     test_lat =  20.0
>     test_lon = 130.0
>     jtest    = toint((test_lat-latS)/dlat)
>     itest    = toint((test_lon-lonW)/dlon)
>
>     if (il .eq. itest .and. jl .eq. jtest) then
>       print (count(jl,il) + "  " + lines(n))
>     end if
>
> In the code above, change test_lat and test_lon to the coordinates of any
> single grid box that you want to check.  Then run the program.  This will
> print every input record that gets counted for that one grid box.
>
> For example, I get 86 counts for the grid box example above, i..e. 20N,
> 130E.
>
> --Dave
>
>
> On Sun, Apr 8, 2018 at 9:04 PM, Lyndz <olagueralyndonmark429 at gmail.com>
> wrote:
>
>> 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.c
>>>>> om> 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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