hf_tobler: Functions for computing hiking velocity

In kbvernon/rHike: Functions for Computing Hiking Efficiency and Velocity

Description

These functions compute velocity for the average hiker as a function of slope.

Usage

hf_tobler(x, on.path = TRUE)

hf_campbell(x, decile = 10)

Arguments

x	Vector Slope values must be in degrees.
on.path	Logical If true (default), the function computes Tobler velocity for on-path hiking. If false, off-path hiking.
decile	Numeric or Integer. Decile of the empirical Campbell distribution for defining coefficients. Possible values include seq(10, 90, by = 10).

Details

Where θ is the slope, velocity is equal to

• Tobler (1993)

  1.6 * exp(-3.5 * θ + 0.5) * d

  where d is a weight equal to 1 for on- and 0.6 for off-path hiking.

• Campbell (2019)

  c * (1\(2b) * exp(0 - |(x-μ)/b|) + ex + d

By default, the Tobler hiking function returns velocity in km/hr. The hf_tobler function converts to m/s.

Value

A vector of velocity values in m/s.

References

Tobler, Waldo R. (1993). "Three Presentations on Geographical Analysis and Modeling: Non-Isotropic Geographic Modeling, Speculations on the Geometry of Geography, and Global Spatial Analysis." National Center for Geographic Information and Analysis, Technical Report 93-1.

Campbell, Michael J., Philip E. Dennison, Bret W. Butler, and Wesley G. Page (2019). "Using crowdsourced fitness tracker data to model the relationship between slope and travel rates. Applied Geography 106, 93-107.

Examples

## Not run: 

slope <- seq(-90, 90, by = 1)

velocity <- hf_tobler(slope, on.path = TRUE)
plot(velocity ~ slope, type = "l", ylab = "velocity")

velocity <- hf_tobler(slope, on.path = FALSE)
plot(velocity ~ slope, type = "l", ylab = "velocity")

velocity <- hf_campbell(slope, decile = 10)
plot(velocity ~ slope, type = "l", ylab = "velocity")


## End(Not run)

kbvernon/rHike documentation built on May 29, 2020, 7:22 p.m.