nhdplusTools (version 0.3.8)

get_flowline_index: Get Flowline Index

Description

given an sf point geometry column, return COMID, reachcode, and measure for each.

Usage

get_flowline_index(flines, points, search_radius = 0.1, precision = NA)

Arguments

flines

sf data.frame of type LINESTRING or MULTILINESTRING including COMID, REACHCODE, ToMeas, and FromMeas

points

sfc of type POINT

search_radius

numeric the distance for the nearest neighbor search to extend. See RANN nn2 documentation for more details.

precision

numeric the resolution of measure precision in the output.

Value

data.frame with four columns, COMID, REACHCODE, REACH_meas, and offset.

Details

Note 1: Inputs are cast into LINESTRINGS. Because of this, the measure output of inputs that are true multipart lines may be in error.

Note 2: This algorithm finds the nearest node in the input flowlines to identify which flowline the point should belong to. As a second pass, it can calculate the measure to greater precision than the nearest flowline geometry node.

Note 3: Offset is returned in units consistant with the projection of the flowlines.

Examples

# NOT RUN {
sample_flines <- sf::read_sf(system.file("extdata",
                                         "petapsco_flowlines.gpkg",
                                         package = "nhdplusTools"))
get_flowline_index(sample_flines,
                   sf::st_sfc(sf::st_point(c(-76.87479,
                                             39.48233)),
                              crs = 4326))

# }