Is there a way to use Fiona instead of OGR to convert a GDB over to postgresql / postgis within Python? If so, how or where can I look? I cannot seem to find this within the Fiona site or by simply Googling around.
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Does this not answer the question -- ie, using gdal from Fiona?John Powell– John Powell2016-07-30 06:40:24 +00:00Commented Jul 30, 2016 at 6:40
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@John Barça I'm not sure I follow you. I can open up a file via Fiona. I can parse through layers using Fiona. What I'm not certain of is a graceful way to CONVERT things to postgresql / postgis. I'm trying to remove OGR calls within Python to be strictly done via Fiona (or so I thought). Can this be done? I thought it should be since Fiona is based off of OGR.George– George2016-08-01 16:57:37 +00:00Commented Aug 1, 2016 at 16:57
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2 Answers
Fiona does not currently connect to PostgreSQL/PostGIS as shown here, and sort-of documented here.
OGR is still a useful tool for PostgreSQL/PostGIS, and other spatial databases.
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Thanks... I wasn't looking to connect... just convert... but maybe you're saying connecting is part of the conversion process? I was just trying to utilize Fiona as much as possible since it's simply an OGR package for Python.George– George2016-08-18 14:31:17 +00:00Commented Aug 18, 2016 at 14:31
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Yes, you must connect to a data source to do anything. In other words, Fiona (at present) does not work with PostGIS, as it is a subset of the functionality provided by OGR.Mike T– Mike T2016-08-18 21:14:15 +00:00Commented Aug 18, 2016 at 21:14
Fiona works with GeoJSON and postgis can produce GeoJSON geometries with ST_AsGeoJSON(wkbgeometry) which you can wrap with other (non-geometry) properties to produce a FeatureCollection. I just figured that out for postgis use with rasterstats. You can do ST_GeomFromGeoJSON() to go the other way.
No OGR needed because you can do this with a plain vanilla database connection (e.g. psycopg2 in python).
Code snippet:
conn = psycopg2.connect(connString)
if not conn:
print("No connection established")
sys.exit(1)
curs = conn.cursor()
sql = """SELECT id, ST_Area(wkb_geometry), ST_Perimeter(wkb_geometry), ST_AsGeoJSON(wkb_geometry)::json
from spatial_db_table
"""
curs.execute(sql)
features = { "type": "FeatureCollection",
"features": [{"type": "feature", "geometry": f[3], "properties": {"id": int(f[0]), "area": float(f[1]), "perimeter": float(f[2])}} for f in curs.fetchall()]}
with rasterio.open('my_raster.tif') as src:
affine = src.transform
array = src.read(1)
zs = zonal_stats(features, array, affine=affine, stats=["count", "mean", "std", "min", "max", "percentile_25", "percentile_50", "percentile_75"], prefix="", nodata=0, geojson_out=True)
print(zs)
