prep.data: Prepare data

In SNMA: Stream Network Movement Analyses

Prepare data

Description

Wrapper function to prepare stream data for analyses

Usage

prep.data(
  l,
  freq = 1,
  nodes,
  lon.name = "lon",
  lat.name = "lat",
  node.name = "id"
)

Arguments

l	(shapefile) A projected polyline loaded with st_read(). Should include an id variable specifying different segments of the stream (this should be included even if there is only a single segment)
freq	(numeric) The distance (in meters) to add points. Default = 1
nodes	(data.frame) A data frame of coordinates for the nodes where stream segments meet or end. Should contain columns for latitude, longitude, and the identity of each node (identities must be integers and go from 1 to number of nodes)
lon.name	(character) Name of the column of longitudes (in quotes). Default = "lon"
lat.name	(character) Name of the column of latitudes (in quotes). Default = "lat"
node.name	(character) Name of the column of segment identities (in quotes). Default = "id"

Details

Takes a shapefile (polyline) of the stream (including all segments (i.e., edges), with each segment having a different ID) as well as a data frame of node locations. It then adds points at the specified interval (to increase accuracy) and does a series of calculations to build reference tables of distances along segments and among nodes.

Segments (edges) are defined as any section between two nodes with no nodes between them. Nodes occur at each start, end, or intersection of segments.

This is the only function needed to prepare data for analyses such as calc.stream.dist, movements, and dist.over.time

Note: All data MUST be in the same projected system. These functions are intended for data formatted in decimal degrees.

Do not use braided streams. If a stream is braided (i.e., channels split then reconnect forming islands) the calculations will be incorrect. If you are working in a braided system, but all of your known movements do not include the braids, simply use a shapefile that does not include the braids (e.g., a study that only tracks in the main channel and largest side channels, without tracking in braided channels)

Value

A list containing five objects:

nodes = (data.frame) Coordinates for the nodes where stream segments meet or end.

increased.line = (data.frame) Coordinates describing the center line of the stream with an increased frequency of points

dps.segments = (data.frame) Total distances of each segment and the nodes defining that segment

dps.distances = (list) List of data frames (one data frame per segment) with the distances between each consecutive pair of points

node.distances = (data.frame) Minimum distance between each pair of nodes (not simply nodes on a given segment)

Examples

data(stream.line)
data(nodes)
network.20 <- prep.data(
  l = stream.line,
  freq = 20,
  nodes = nodes,
  lon.name = "lon",
  lat.name = "lat",
  node.name = "id"
)

SNMA documentation built on Aug. 27, 2026, 1:08 a.m.