[ncl-talk] converting shapefile to netcdf

[Dave Allured - NOAA Affiliate]

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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