read_shapefile doesn't pick up crs (also, not sure how to get crs without pyarrow)

[deanm0000]

I tried with this file https://www2.census.gov/geo/tiger/GENZ2018/shp/cb_2018_us_state_500k.zip

grctab = read_shapefile(shpfile, dbffile)
patab = pa.table(grctab)
pa.table(gg)['geometry'].type.crs
## returns
''

gpdtab = gpd.read_file(shp_file_dir)
gpdtab.crs
## returns
<Geographic 2D CRS: EPSG:4269>
Name: NAD83
Axis Info [ellipsoidal]:
- Lat[north]: Geodetic latitude (degree)
- Lon[east]: Geodetic longitude (degree)
Area of Use:
- name: North America - onshore and offshore: Canada - Alberta; British Columbia; Manitoba; New Brunswick; Newfoundland and Labrador; Northwest Territories; Nova Scotia; Nunavut; Ontario; Prince Edward Island; Quebec; Saskatchewan; Yukon. Puerto Rico. United States (USA) - Alabama; Alaska; Arizona; Arkansas; California; Colorado; Connecticut; Delaware; Florida; Georgia; Hawaii; Idaho; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Montana; Nebraska; Nevada; New Hampshire; New Jersey; New Mexico; New York; North Carolina; North Dakota; Ohio; Oklahoma; Oregon; Pennsylvania; Rhode Island; South Carolina; South Dakota; Tennessee; Texas; Utah; Vermont; Virginia; Washington; West Virginia; Wisconsin; Wyoming. US Virgin Islands. British Virgin Islands.
- bounds: (167.65, 14.92, -40.73, 86.45)
Datum: North American Datum 1983
- Ellipsoid: GRS 1980
- Prime Meridian: Greenwich

As an aside, I would just make a request that instead of taking the two files as input it would just take the directory or, for bonus points, a zip file containing a shapefile directory.

[kylebarron]

The shapefile reader does not yet handle files other than .shp and .dbf. Help would be appreciated to ensure we handle the .cpg file (for the text encoding in the .dbf) and the .prj file.

One blocker here is that in the GeoArrow spec we currently require PROJJSON. That needs to be relaxed to allow any CRS information, because we have no way to convert the .prj file to PROJJSON. See https://github.com/geoarrow/geoarrow/pull/40/files

[kylebarron]

You can use geoarrow.rust.core.get_crs to access the CRS of a file. See

geoarrow-rs/python/geoarrow-core/python/geoarrow/rust/core/_crs.py

Lines 14 to 18 in 3ecf7df

	def get_crs(
	data: ArrowArrayExportable | ArrowStreamExportable | ArrowSchemaExportable,
	/,
	column: str | None = None,
	) -> pyproj.CRS | None:

But it looks like we're missing that function from the docs.