logistic

<code>vector</code> or <code>raster*</code> object to apply logistic transform.

lower

upper

The rate of decay.
A rate of 0 indicates no decay, while large rates (>10) become like step-functions.

rate

Affects near which asymptote maximum rate (<code>skew</code> must be >0).
If skew=1, the curve becomes a standard symetrical logistic centered at <code>m</code>.    
As skew approaches zero, it becomes more asymetrical.

skew

The time of maximum decay. Slides the curve left-right.

shift

an optional list with each of the following named parameters
(e.g. <code>list(lower=0.01,upper=1,rate=0.04,skew=0.2,shift=0)</code>).
Use of <code>parms</code> rather than naming each parameter separately is for
convenience with the <code><a rd-options="" href="/link/optim?package=bossMaps&version=0.1.0" data-mini-rdoc="bossMaps::optim">optim</a></code> function.

parms


Performs a generalized logistic transform (aka Richard's curve) as follows:
 $$Y(t) = upper - { upper-lower \over (1 + e^{-rate(x - shift)}) ^ {1 / skew} }$$


Contains functions to convert binary (presence-absence) expert species range maps (like those found in a field guide) into continuous surfaces based on distance to range edge.  These maps can then be used in species distribution models such as Maximum Entropy (Phillips 2008 <DOI:10.1111/j.0906-7590.2008.5203.x>) using additional information (such as point occurrence data) to refine the expert map.

Adam M. Wilson adamw@buffalo.edu

bossMaps

Convert Binary Species Range Maps into Continuous Surfaces Based
on Distance to Range Edge

logistic function

an optional list with each of the following named parameters
(e.g. <code>list(lower=0.01,upper=1,rate=0.04,skew=0.2,shift=0)</code>).
Use of <code>parms</code> rather than naming each parameter separately is for
convenience with the <code><a rd-options='' href='optim'>optim</a></code> function.

logistic: Apply a custom logisitic transform to a vector

Description

Usage

Arguments

References

Examples