# [ncl-talk] area of a shapefile

Dennis Shea shea at ucar.edu
Mon Mar 12 08:25:03 MDT 2018

```You could click "Functions" [Alphabetical]; then, search for the word 'area'
Keep clicking ....

https://www.ncl.ucar.edu/Document/Functions/Built-in/area_poly_sphere.shtml

Also,
https://www.ncl.ucar.edu/Document/Functions/Built-in/gc_qarea.shtml
See Examples

Good luck

On Mon, Mar 12, 2018 at 8:14 AM, Vanúcia Schumacher <
vanucia-schumacher at hotmail.com> wrote:

>       Hi NCL users,
>
> I would like help to calculate the area from the shapefile.
> Any ideas how can I proceed?
>
>
>        ncols = stringtoint( str_get_field(hdr(0), 2, " ") )
>       nrows = stringtoint( str_get_field(hdr(1), 2, " ") )
>        lonLL = stringtofloat( str_get_field(hdr(2), 2, " ") )
>         latLL = stringtofloat( str_get_field(hdr(3), 2, " ") )
>   deltaLon = stringtofloat( str_get_field(hdr(4), 2, " " ) )
>   deltaLat = stringtofloat( str_get_field(hdr(5), 2, " ") )
> missingVal = stringtofloat( str_get_field(hdr(6), 2, " ") )
>
>                      data at _FillValue =-9999.0
>
> ;----- construct 1D coordinates....
> lons             = ispan(0,ncols-1,1) * deltaLon + lonLL
> lats             = ispan(0,nrows-1,1) * deltaLat + latLL
> lats             = lats(::-1)
>
> ;---- gsn_coordinates wants 2D coordinate arrays
> data at lon2d       = conform_dims((/ nrows, ncols/), lons, 1)
> data at lat2d       = conform_dims((/ nrows, ncols/), lats, 0)
> data at _FillValue  = missingVal
>
> ;---- Open shapefile and read lat/lon values.
>
>
> ;--- Area ?
>
>
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