Create netgeom column in SSN object — create

Create netgeom column for edges, observed sites, and/or prediction sites in a Landscape Network (LSN).

create_netgeom(sf_data, type = NULL, overwrite = FALSE)

Arguments

sf_data: An sf object with LINESTING or POINT geometry created using link{lsn_to_ssn} (see Details).
type: Character string defining geometry type of sf_data. Default = NULL.
overwrite: Logical indicating whether existing data should be overwritten if present. Default = FALSE.

Value

An sf object containing the original data from sf_data and an additional column named netgeom.

Details

Most users will not need to run create_netgeom themselves because it is called internally when lsn_to_ssn is run or an SSN is imported using link[SSN2]{ssn_import} found in the SSN2 package. For users who do wish to run create_netgeom, the sf_data object must represent edges, observed sites, or prediction sites in a SSN object created using link{lsn_to_ssn}.

The netgeom column contains information in character format used to describe the topology of the LSN. The format and content of the netgeom column differs depending on whether sf_data contains LINESTRING (edges) or POINT (observed or prediction sites) geometry. For edges, the netgeom format is:

'ENETWORK (netID, rid, upDist)'

For observed or prediction sites, the netgeom format is:

'SNETWORK (netID, rid, upDist, ratio, pid, locID)'

The rid, ratio, upDist, netID, pid, and locID columns must be present in sf_data before netgeom is added.

If overwrite = TRUE and a column named netgeom is present in sf_data, the data will be overwritten. Default = FALSE.

Examples

## Create local temporary copy of MiddleFork04.ssn found in
## the SSN2 package. Only necessary for this example.
copy_lsn_to_temp()

# Import the SSN object with prediction points, pred1km
mf04<- ssn_import(
   paste0(tempdir(), "/MiddleFork04.ssn"),
   predpts = c("pred1km"),
   overwrite = TRUE
)

# Recalculate the netgeom column for the observed sites
sf_obs <- create_netgeom(
    mf04$obs,
    type = "POINT",
    overwrite = TRUE
)

# Recalculate the netgeom column for the edges
sf_edges <- create_netgeom(
    mf04$edges,
    type = "LINESTRING",
    overwrite = TRUE
)