nngeo: st_postgis – R documentation

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st_postgis

Send 'sf' layer to a PostGIS query

Description

The function sends a query plus an sf layer to PostGIS, saving the trouble of manually importing the layer and exporting the result

Usage

st_postgis(x, con, query, prefix = "temporary_nngeo_layer_")

Arguments

`x`	Object of class `sf`
`con`	Connection to PostgreSQL database with PostGIS extension enabled. Can be created using function `RPostgreSQL::dbConnect`
`query`	SQL query, which may refer to layer `x` as `x` and to the geometry column of the `x` layer as `geom` (see examples)
`prefix`	Prefix for storage of temporarily layer in the database

Value

Returned result from the database: an sf layer in case the result includes a geometry column, otherwise a data.frame

Examples

## Not run: 

# Database connection and 'sf' layer
source("~/Dropbox/postgis_159.R")  ## Creates connection object 'con'
x = towns

# Query 1: Buffer
query = "SELECT ST_Buffer(geom, 0.1, 'quad_segs=2') AS geom FROM x LIMIT 5;"
st_postgis(x, con, query)

# Query 2: Extrusion
query = "SELECT ST_Extrude(geom, 0, 0, 30) AS geom FROM x LIMIT 5;"
st_postgis(x, con, query)

## End(Not run)

nngeo

k-Nearest Neighbor Join for Spatial Data

v0.4.2

MIT + file LICENSE

Authors

Michael Dorman [aut, cre], Johnathan Rush [ctb], Ian Hough [ctb], Dominic Russel [ctb], Luigi Ranghetti [ctb], Charles F.F Karney [ctb, cph] (Author of included C code from 'GeographicLib' for geodesic distance)

Initial release