setSearchVolume.Rd

% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/setSearchVolume.R
\name{setSearchVolume}
\alias{setSearchVolume}
\alias{getSearchVolume}
\alias{search_vol}
\alias{search_vol<-}
\title{Set search volume}
\usage{
setSearchVolume(params, search_vol = NULL, reset = FALSE, ...)

getSearchVolume(params)

search_vol(params)

search_vol(params) <- value
}
\arguments{
\item{params}{MizerParams}

\item{search_vol}{Optional. An array (species x size) holding the search volume
for each species at size. If not supplied, a default is set as described in
the section "Setting search volume".}

\item{reset}{\ifelse{html}{\href{https://lifecycle.r-lib.org/articles/stages.html#experimental}{\figure{lifecycle-experimental.svg}{options: alt='[Experimental]'}}}{\strong{[Experimental]}}
If set to TRUE, then the search volume will be reset to the
value calculated from the species parameters, even if it was previously
overwritten with a custom value. If set to FALSE (default) then a
recalculation from the species parameters will take place only if no custom
value has been set.}

\item{...}{Unused}

\item{value}{search_vol}
}
\value{
\code{setSearchVolume()}: A MizerParams object with updated search volume.

\code{getSearchVolume()} or equivalently \code{search_vol()}: An array (species
x size) holding the search volume
}
\description{
Set search volume
}
\section{Setting search volume}{

The search volume \eqn{\gamma_i(w)} of an individual of species \eqn{i}
and weight \eqn{w} multiplies the predation kernel when
calculating the encounter rate in \code{\link[=getEncounter]{getEncounter()}} and the
predation rate in \code{\link[=getPredRate]{getPredRate()}}.

The name "search volume" is a bit misleading, because \eqn{\gamma_i(w)} does
not have units of volume. It is simply a parameter that determines the rate
of predation. Its units depend on your choice, see section "Units in mizer".
If you have chosen to work with total abundances, then it is a rate with units
1/year. If you have chosen to work with abundances per m^2 then it has units
of m^2/year. If you have chosen to work with abundances per m^3 then it has
units of m^3/year.

If the \code{search_vol} argument is not supplied, then the search volume is
set to
\deqn{\gamma_i(w) = \gamma_i w^q_i.}
The values of \eqn{\gamma_i} (the search volume at 1g) and \eqn{q_i} (the
allometric exponent of the search volume) are taken from the \code{gamma} and
\code{q} columns in the species parameter dataframe. If the \code{gamma}
column is not supplied in the species parameter dataframe, a default is
calculated by the \code{\link[=get_gamma_default]{get_gamma_default()}} function. Note that only
for predators of size \eqn{w = 1} gram is the value of the species parameter
\eqn{\gamma_i} the same as the value of the search volume \eqn{\gamma_i(w)}.
}

\seealso{
Other functions for setting parameters: 
\code{\link{gear_params}()},
\code{\link{setExtEncounter}()},
\code{\link{setExtMort}()},
\code{\link{setFishing}()},
\code{\link{setInitialValues}()},
\code{\link{setInteraction}()},
\code{\link{setMaxIntakeRate}()},
\code{\link{setMetabolicRate}()},
\code{\link{setParams}()},
\code{\link{setPredKernel}()},
\code{\link{setReproduction}()},
\code{\link{species_params}()}
}
\concept{functions for setting parameters}