cholera (version 0.4.0)

walkingDistance: Compute the shortest walking distance between cases and/or pumps.

Description

Compute the shortest walking distance between cases and/or pumps.

Usage

walkingDistance(origin, destination = NULL, type = "case-pump",
  observed = TRUE, weighted = TRUE, vestry = FALSE, unit = NULL)

Arguments

origin

Numeric or Integer. Numeric ID of case or pump.

destination

Numeric or Integer. Numeric ID(s) of case(s) or pump(s). Exclusion is possible via negative selection (e.g., -7). Default is NULL: this returns closest pump or "anchor" case.

type

Character "case-pump", "cases" or "pumps".

observed

Logical. Use observed or "simulated" expected data.

weighted

Logical. TRUE computes shortest path in terms of road length. FALSE computes shortest path in terms of nodes.

vestry

Logical. TRUE uses the 14 pumps from the Vestry Report. FALSE uses the 13 in the original map.

unit

Character. Unit of measurement: "meter" or "yard". Default is NULL, which returns the map's native scale. Meaningful only when "weighted" is TRUE. See vignette("roads") for information on unit distances.

Value

An R list.

See Also

fatalities, vignette("pump.neighborhoods")

Examples

# NOT RUN {
# path from case 1 to nearest pump.
# walkingDistance(1)

# path from case 1 to nearest pump in meters (appox).
# walkingDistance(1, unit = "meter")

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

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

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

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

# Plot result
# plot(walkingDistance(1, unit = "meter"))
# }