fast_density: Fast Density

In byu-transpolab/gpsactivs: Extract Activities and Semantic Locations from GPS Trace Data

Description

The algorithm has its basis in the assumptions that cluster centers are surrounded by neighbors with lower local density and that they are at a relatively large distance from any points with a higher local density.

Usage

fast_density(trajectory, d_threshold)

Arguments

trajectory	A projected sf points dataframe representing a trajectory.
d_threshold	A distance (in units of the projection system) to include in the cluster search.

Details

For each data point 'i', we compute two quantities: its local density 'rho_i' and its distance 'delta_i' from points of higher density. Both these quantities depend only on the distances Embedded Image between data points, which are assumed to satisfy the triangular inequality. The local density Embedded Image of data point Embedded Image is defined as

byu-transpolab/gpsactivs documentation built on Dec. 19, 2021, 12:51 p.m.