[ncl-talk] converting shapefile to netcdf

[Dave Allured - NOAA Affiliate]

Hiep, please keep the mailing list in all replies.

"Convert from netcdf file back to shapefile?"  Can you be a little more
specific about what kind of data in the netcdf file, and what you would
want the shape file to look like?


On Wed, Nov 27, 2019 at 2:07 AM Hiep Duc <Hiep.Duc at environment.nsw.gov.au>
wrote:

> Hi all,
>
>
>
> Is it possible to convert from netcdf file back to shapefile ?.
>
> Or is this transformation one way only ?
>
> Thanks
>
> Hiep
>
>
>
> *From:* ncl-talk <ncl-talk-bounces at ucar.edu> *On Behalf Of *Dave Allured
> - NOAA Affiliate via ncl-talk
> *Sent:* Wednesday, 27 November 2019 6:27 PM
> *To:* Amy Hendricks <ashendricks at alaska.edu>
> *Cc:* ncl-talk at ucar.edu
> *Subject:* Re: [ncl-talk] converting shapefile to netcdf
>
>
>
> Correction, the name of this example is shapefiles_14_mask, not just
> shapefiles_14.
>
>
>
>
>
> On Tue, Nov 26, 2019 at 8:57 PM Dave Allured - NOAA Affiliate <
> dave.allured at noaa.gov> wrote:
>
> Example shapefiles_14 is close to what you want.  Please notice these two
> lines.  Their function is to select a particular subset of all the state
> outlines in the example shapefile, then apply a binary mask to the base
> grid "tc_lev0" so that only grid points over the listed states are
> retained.  All grid points outside this list of states are set to missing.
> This demonstrates how to access a subset of a shape file, instead of all
> regions together,
>
>    opt at shape_names = (/"Texas","New
> Mexico","Colorado","Kansas","Oklahoma"/)
>    tc_mask  = shapefile_mask_data(tc_lev0,shp_filename1,opt)
>
> For your application, use this masking function to select one region at a
> time.  Start with a master grid with ERA5 coordinates, set to all zero or
> missing values.  Loop over each region value or region number.  Call the
> function shapefile_mask_data inside the loop, selecting the grid points for
> only one region each time. Use the resulting binary mask to add the
> current region number to the master grid.  When the loop is complete, write
> the master grid with all region numbers to a Netcdf file.
>
>
>
>
>
> On Tue, Nov 26, 2019 at 3:51 PM Amy Hendricks via ncl-talk <
> ncl-talk at ucar.edu> wrote:
>
> Hello NCL geniuses,
>
>
>
> I am trying to write a shapefile to netcdf. The shapefile consists of
> circumpolar Treshnikov regions, and I would like to create a netCDF file
> that has the region values like tresh(lon,lat) = [region# from shapefile]
> on the ERA5 grid. All the examples I'm finding are for creating binary
> masks, and the ncl_convert2nc does not seem to work, at least it doesn't
> return anything useable.
>
>
>
> Attached are the ERA5 netCDF file, Treshnikov shapefile, as well as the
> result of ncl_convert2nc.
>
>
>
> Thank you in advance,
>
>
>
> Amy
>
>
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