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Index Points to Lines

Source: R/index_points_to_lines.R
index_points_to_lines.Rd

given an sf point geometry column, return id, aggregate_id (e.g. reachcode), and aggregate id measure for each point.

Usage

index_points_to_lines(
  x,
  points,
  search_radius = NULL,
  precision = NA,
  max_matches = 1
)

# S3 method for data.frame
index_points_to_lines(
  x,
  points,
  search_radius = NULL,
  precision = NA,
  max_matches = 1
)

# S3 method for hy
index_points_to_lines(
  x,
  points,
  search_radius = NULL,
  precision = NA,
  max_matches = 1
)

Arguments

x

data.frame network compatible with hydroloom_names.

points

sf or sfc of type POINT in analysis projection. NOTE: x will be projected to the projection of the points layer.

search_radius

units distance for the nearest neighbor search to extend in analysis projection. If missing or NULL, and points are in a lon lat projection, a default of 0.01 degree is used, otherwise 200 m is used. Conversion to the linear unit used by the provided crs of points is attempted. See RANN nn2 documentation for more details.

precision

numeric the resolution of measure precision in the output in meters.

max_matches

numeric the maximum number of matches to return if multiple are found in search_radius

Value

data.frame with five columns, point_id, id, aggregate_id, aggregate_id_measure, and offset. point_id is the row or list element in the point input.

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 consistent with the projection of the input points.

Note 4: See dfMaxLength input to sf::st_segmentize() for details of handling of precision parameter.

Note 5: "from" is downstream -- 0 is the outlet "to" is upstream -- 100 is the inlet

Examples


# \donttest{
if(require(nhdplusTools)) {
source(system.file("extdata", "sample_flines.R", package = "nhdplusTools"))

point <- sf::st_sfc(sf::st_point(c(-76.87479, 39.48233)),
                    crs = 4326)

index_points_to_lines(sample_flines, point)

point <- sf::st_transform(point, 5070)

index_points_to_lines(sample_flines, point,
                      search_radius = units::set_units(200, "m"))

index_points_to_lines(sample_flines, point, precision = 30)

index_points_to_lines(sample_flines,
                      sf::st_sfc(list(sf::st_point(c(-76.86934, 39.49328)),
                                      sf::st_point(c(-76.91711, 39.40884)),
                                      sf::st_point(c(-76.88081, 39.36354))),
                                 crs = 4326),
                      search_radius = units::set_units(0.2, "degrees"),
                      max_matches = 10)

 }
#> Warning: converting to LINESTRING, this may be slow, check results
#> Warning: crs of lines and points don't match. attempting st_transform of lines
#> Warning: converting to LINESTRING, this may be slow, check results
#> Warning: crs of lines and points don't match. attempting st_transform of lines
#> Warning: converting to LINESTRING, this may be slow, check results
#> Warning: converting to LINESTRING, this may be slow, check results
#>    point_id    COMID      REACHCODE REACHCODE_measure       offset
#> 1         1 11688298 02060003000579            0.0000 6.026811e-05
#> 2         2 11688808 02060003000519           53.5874 5.641410e-04
#> 3         3 11688980 02060003000253           75.3779 3.102970e-04
#> 4         1 11689926 02060003001467          100.0000 6.026811e-05
#> 5         3 11688950 02060003000254           18.5358 1.131181e-03
#> 6         1 11689928 02060003001468            0.0000 2.026592e-03
#> 7         1 11689978 02060003001472          100.0000 2.026592e-03
#> 8         1 11690530 02060003000585            0.0000 2.853201e-03
#> 9         1 11690490 02060003000580            0.0000 2.853201e-03
#> 10        3 11688948 02060003000516            0.0000 3.207544e-03
#> 11        2 11690110 02060003001493          100.0000 7.424781e-03
#> 12        1 11690532 02060003000256            0.0000 4.513088e-03
#> 13        2 11688822 02060003000518           39.5280 7.677891e-03
#> 14        1 11688296 02060003000584            0.0000 6.017732e-03
#> 15        1 11688338 02060003000581            0.0000 6.017732e-03
#> 16        2 11688742 02060003000521            0.0000 8.549572e-03
#> 17        3 11689022 02060003000252           54.2321 6.961051e-03
#> 18        2 11688778 02060003000520            0.0000 8.549572e-03
#> 19        1 11687550 02060003000585           18.5588 6.832206e-03
#> 20        2 11690112 02060003001494          100.0000 9.547712e-03
#> 21        3 11688990 02060003000515            1.9144 8.652186e-03
#> 22        2 11690122 02060003001495          100.0000 1.026162e-02
#> 23        3 11689016 02060003000294           18.9609 1.162680e-02
#> 24        2 11688868 02060003000517           27.7564 1.694256e-02
#> 25        3 11689072 02060003000251          100.0000 1.366486e-02
#> 26        2 11690124 02060003001496          100.0000 1.953370e-02
#> 27        3 11690130 02060003001499            0.0000 1.638423e-02
#> 28        2 11690128 02060003001498          100.0000 2.099143e-02
#> 29        3 11689696 02060003000387            0.4731 1.872134e-02
#> 30        3 11689006 02060003000295            0.0000 1.876644e-02
 # }