setSearchVolume: Set search volume
Description
Set search volume
Usage
setSearchVolume(params, search_vol = NULL, reset = FALSE, ...)getSearchVolume(params)
search_vol(params)
search_vol(params) <- value
Value
setSearchVolume(): A MizerParams object with updated search volume.
getSearchVolume() or equivalently search_vol(): An array (species
x size) holding the search volume
Arguments
- params
MizerParams
- 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".
- reset
![[Experimental]](figures/lifecycle-experimental.svg?package=mizer&version=2.5.3)
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.- ...
Unused
- value
search_vol
Setting search volume
The search volume \(\gamma_i(w)\) of an individual of species \(i\)
and weight \(w\) multiplies the predation kernel when
calculating the encounter rate in getEncounter() and the
predation rate in getPredRate().
The name "search volume" is a bit misleading, because \(\gamma_i(w)\) 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 search_vol argument is not supplied, then the search volume is
set to
$$\gamma_i(w) = \gamma_i w^q_i.$$
The values of \(\gamma_i\) (the search volume at 1g) and \(q_i\) (the
allometric exponent of the search volume) are taken from the gamma and
q columns in the species parameter dataframe. If the gamma
column is not supplied in the species parameter dataframe, a default is
calculated by the get_gamma_default() function. Note that only
for predators of size \(w = 1\) gram is the value of the species parameter
\(\gamma_i\) the same as the value of the search volume \(\gamma_i(w)\).
See Also
Other functions for setting parameters:
gear_params(),
setExtEncounter(),
setExtMort(),
setFishing(),
setInitialValues(),
setInteraction(),
setMaxIntakeRate(),
setMetabolicRate(),
setParams(),
setPredKernel(),
setReproduction(),
species_params()