potential: Processes the potential (or gravity) accessibility.
In biamouras/accSeg: Functions for my MSc analysis

Description Usage Arguments Details Value Author(s) References

View source: R/accessibility_functions.R

Uses the negative exponential (exponential type) or the gaussian (gaussian type) functions to weight the oportunities.

potential(
  oportunities,
  matrix,
  type = "exponential",
  betas = NULL,
  cutoff = NULL
)

`oportunities`	data frame with id and oportunity structure.
`matrix`	data frame with origin, destination and travel_time/distance structure.
`type`	string to choose between exponential and gaussian function to decay the oportunities. Defaults to exponential.
`betas`	numeric 'willing' decay factor. It must be defined when type "exponential" is chosen. Defaults to NULL.
`cutoff`	numeric threshold. It must be in the same unit of the matrix and it must be defined when type "gaussian" is chosen. Defaults to NULL.

The negative exponential function is one of the most used impedance functions in recent studies of gravity-based accessibility (Handy & Niemeier, 1997). In order to avoid the rapid decline of the negative exponential function, Ingram (1971) proposed the use of the normal (gaussian) function, as it declines smoother than the former.

data frame with origin and acc. If gaussian type is chosen, adds the threshold column.

Beatriz Moura dos Santos

Hansen (1959). How accessibility shapes land use. Journal of the American Institute of planners, 25(2), 73-76.

Ingram (1971). The concept of accessibility: a search for an operational form. Regional studies, 5(2), 101-107.

Handy & Niemeier (1997). Measuring accessibility: An exploration of issues and alternatives. Environment and Planning A: Economy and Space, 29(7), 1175-1194.

biamouras/accSeg documentation built on Nov. 19, 2020, 8:07 a.m.