euclideanPath: Compute path of the Euclidean distance between cases and/or...

In cholera: Amend, Augment and Aid Analysis of John Snow's Cholera Map

Compute path of the Euclidean distance between cases and/or pumps.

Description

Compute path of the Euclidean distance between cases and/or pumps.

Usage

euclideanPath(origin = 1, destination = NULL, type = "case-pump",
  observed = TRUE, case.location = "nominal", landmark.cases = TRUE,
  vestry = FALSE, distance.unit = "meter", time.unit = "second",
  walking.speed = 5)

Arguments

origin	Numeric or Character. Numeric ID of case or pump. Character landmark name.
destination	Numeric or Character. Numeric ID(s) of case(s) or pump(s). Exclusion is possible via negative selection (e.g., -7). Default is NULL, which returns the closest pump, "anchor" case or landmark.
type	Character "case-pump", "cases" or "pumps".
observed	Logical. Use observed or "simulated" expected data.
case.location	Character. For observed = FALSE: "address" or "nominal". "nominal" is the x-y coordinates of regular.cases.
landmark.cases	Logical. TRUE includes landmarks as cases.
vestry	Logical. TRUE uses the 14 pumps from the Vestry Report. FALSE uses the 13 pumps from the original map.
distance.unit	Character. Unit of distance: "meter", "yard" or "native". "native" returns the map's native scale. See vignette("roads") for information on unit distances.
time.unit	Character. "hour", "minute", or "second".
walking.speed	Numeric. Default is 5 km/hr.

Value

An R list with 3 data frames: x-y coordinates for the origin and destination, and a summary of results.

Note

The function uses a case's "address" (i.e., "anchor" case of a stack) to compute distance. Time is computed using distanceTime().

Examples

# path from case 1 to nearest pump.
euclideanPath(1)

# path from pump 1 to nearest case.
euclideanPath(NULL, 1)

# path from case 1 to pump 6.
euclideanPath(1, 6)

# exclude pump 7 from consideration.
euclideanPath(1, -7)

# path from case 1 to case 6.
euclideanPath(1, 6, type = "cases")

# path from pump 1 to pump 6.
euclideanPath(1, 6, type = "pumps")

# compute multiple cases.
lapply(1:3, euclideanPath)

# plot path
plot(euclideanPath(1))

cholera documentation built on March 7, 2023, 5:31 p.m.