{"id": "spatialite:installing-spatialite-on-linux", "page": "spatialite", "ref": "installing-spatialite-on-linux", "title": "Installing SpatiaLite on Linux", "content": "SpatiaLite is packaged for most Linux distributions. \n                 apt install spatialite-bin libsqlite3-mod-spatialite \n                 Depending on your distribution, you should be able to run Datasette something like this: \n                 datasette --load-extension=/usr/lib/x86_64-linux-gnu/mod_spatialite.so \n                 If you are unsure of the location of the module, try running  locate mod_spatialite  and see what comes back.", "breadcrumbs": "[\"SpatiaLite\", \"Installation\"]", "references": "[]"}
{"id": "spatialite:querying-polygons-using-within", "page": "spatialite", "ref": "querying-polygons-using-within", "title": "Querying polygons using within()", "content": "The  within()  SQL function can be used to check if a point is within a geometry: \n             select\n    name\nfrom\n    places\nwhere\n   within(GeomFromText('POINT(-3.1724366 51.4704448)'), places.geom); \n             The  GeomFromText()  function takes a string of well-known text. Note that the order used here is  longitude  then   latitude . \n             To run that same  within()  query in a way that benefits from the spatial index, use the following: \n             select\n    name\nfrom\n    places\nwhere\n    within(GeomFromText('POINT(-3.1724366 51.4704448)'), places.geom)\n    and rowid in (\n        SELECT pkid FROM idx_places_geom\n        where xmin < -3.1724366\n        and xmax > -3.1724366\n        and ymin < 51.4704448\n        and ymax > 51.4704448\n    );", "breadcrumbs": "[\"SpatiaLite\"]", "references": "[]"}
{"id": "spatialite:spatial-indexing-latitude-longitude-columns", "page": "spatialite", "ref": "spatial-indexing-latitude-longitude-columns", "title": "Spatial indexing latitude/longitude columns", "content": "Here's a recipe for taking a table with existing latitude and longitude columns, adding a SpatiaLite POINT geometry column to that table, populating the new column and then populating a spatial index: \n             import sqlite3\n\nconn = sqlite3.connect(\"museums.db\")\n# Lead the spatialite extension:\nconn.enable_load_extension(True)\nconn.load_extension(\"/usr/local/lib/mod_spatialite.dylib\")\n# Initialize spatial metadata for this database:\nconn.execute(\"select InitSpatialMetadata(1)\")\n# Add a geometry column called point_geom to our museums table:\nconn.execute(\n    \"SELECT AddGeometryColumn('museums', 'point_geom', 4326, 'POINT', 2);\"\n)\n# Now update that geometry column with the lat/lon points\nconn.execute(\n    \"\"\"\n    UPDATE museums SET\n    point_geom = GeomFromText('POINT('||\"longitude\"||' '||\"latitude\"||')',4326);\n\"\"\"\n)\n# Now add a spatial index to that column\nconn.execute(\n    'select CreateSpatialIndex(\"museums\", \"point_geom\");'\n)\n# If you don't commit your changes will not be persisted:\nconn.commit()\nconn.close()", "breadcrumbs": "[\"SpatiaLite\"]", "references": "[]"}
{"id": "spatialite:spatialite-installation", "page": "spatialite", "ref": "spatialite-installation", "title": "Installation", "content": "", "breadcrumbs": "[\"SpatiaLite\"]", "references": "[]"}