hill_utils: Functions to solve the Hill model

Description Usage Arguments Details Examples

Description

These functions solve for Hill model parameters.

Usage

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tcplHillACXX(XX, tp, ga, gw, bt = 0)

tcplHillConc(val, tp, ga, gw, bt = 0)

tcplHillVal(logc, tp, ga, gw, bt = 0)

Arguments

XX

Numeric, the activity level (percentage of the top value)

tp

Numeric, the top value from the Hill model

ga

Numeric, the logAC50 value from the Hill model

gw

Numeric, the Hill coefficient from the Hill model

bt

Numeric, the bottom value from the Hill model

val

Numeric, the activity value

logc

Numeric, the log concentration

Details

tcplHillVal computes the value of the Hill model for a given log concentration.

tcplHillACXX computes the activity concentration for a Hill model for a given activity level.

tcplHillConc computes the Hill model concentration for a given value.

Examples

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## The following code gives examples for a Hill model with a top of 50, 
## bottom of 0, AC50 of 1 and Hill coefficient of 1.
## tcplHillVal calculates activity value given a concentration. tcplHillVal
## will return the tp/2 when logc equals ga:
tcplHillVal(logc = 1, tp = 50, ga = 1, gw = 1, bt = 0)

## Here, tcplHillConc returns the concentration where the value equals 20
tcplHillConc(val = 20, tp = 50, ga = 1, gw = 1, bt = 0)

## Note how this differs from tcplHillACXX:
tcplHillACXX(XX = 20, tp = 50, ga = 1, gw = 1, bt = 0)

## tcplHillACXX is based on the top value and allows the user to calculate 
## specifc activity concentrations based on a percentage of the top value

## For example, we can calculate the value for the concentration 0.25, then
## use that value to check the other two functions.

value <- tcplHillVal(logc = 0.25, tp = 50, ga = 1, gw = 1, bt = 0)
c1 <- tcplHillConc(val = value, tp = 50, ga = 1, gw = 1, bt = 0)
c2 <- tcplHillACXX(XX = value/50*100, tp = 50, ga = 1, gw = 1, bt = 0)
all.equal(0.25, c1, c2)

## Notice, the value had to be transformed to a percentage of the top value
## when using tcplHillACXX

USEPA/CompTox-ToxCast-tcpl documentation built on May 5, 2019, 4:48 p.m.