Delayed read for vector resources — as

A lazy data frame for GDAL vector data sources. as_ogr is DBI compatible and designed to work with dplyr.

Usage

as_ogr(x, layer, ..., query = NA, ignore_lyrs = .hf_ignore_lyrs)

# S3 method for class 'character'
as_ogr(x, layer, ..., query = NA, ignore_lyrs = .hf_ignore_lyrs)

# S3 method for class 'OGRSQLConnection'
as_ogr(x, layer, ..., query = NA, ignore_lyrs = .hf_ignore_lyrs)

Arguments

x: the data source (file path, url, or database connection)
layer: layer name (varies by driver, may be a file name without extension); in case layer is missing, st_read will read the first layer of dsn, give a warning and (unless quiet = TRUE) print a message when there are multiple layers, or give an error if there are no layers in dsn. If dsn is a database connection, then layer can be a table name or a database identifier (see Id). It is also possible to omit layer and rather use the query argument.
...: parameter(s) passed on to st_as_sf
query: SQL query to pass in directly
ignore_lyrs: Regular expression matching tables that are data-source plumbing rather than user layers, excluded when `layer` is not given. The default drops GeoPackage spec tables (`^gpkg_`), spatial indexes (`^rtree_`), SQLite internals (`^sqlite_`), and the two tables QGIS writes into a GeoPackage when you save a style or a project to it (`layer_styles`, `qgis_projects`). Patterns are anchored, so a layer whose name merely contains one of these is not dropped.

Value

a 'tbl_OGRSQLConnection'

Details

The output of `as_ogr()` is a 'tbl_OGRSQLConnection` that extends `tbl_dbi` and may be used with functions and workflows in the normal DBI way, see [OGRSQL()] for the as_ogr DBI support.

To obtain an in memory data frame use an explicit `collect()` or `st_as_sf()`. A call to `collect()` is triggered by `st_as_sf()` and will add the sf class to the output.

Examples

if (FALSE) { # \dontrun{
library(dplyr)
tbl <- as_ogr("hydrofabric.gpkg", "flowpaths")
tbl |> filter(order >= 4) |> st_as_sf()
} # }