Select active vessels for a selection of years
Active vessels:
The active_vessels can be either time-dependent,ie given by year/month, year only
or be atemporal, mainly depending on how and at which frequency the vessels census/survey is
operated in the country.
An additional argument called active_vessels_strategy controls how to select the active_vessels data in time,
when this data is time-dependent. The latest strategy will select the latest data acquired in time, while the closest
will select the closest data acquired in time, which could be data acquired after the effort data considered.
As example, a vessel census is performed each five years, and data is available for 2007 and 2012. Effort data for 2011
needs to be computed. Which active_vessels data should be used? In case of a latest strategy, in 2011,
the latest data available is 2007, so this one will be used. In the case of a closest strategy, in 2011, we used
the closest vessel data (ie 2012), assuming it betters characterizes the fleet engagement for the year considered.
Usage
select_active_vessels(
periods,
active_vessels,
active_vessels_strategy = c("latest", "closest")
)Arguments
- periods
periods, list of unique years or year/month periods
- active_vessels
active vessels object of class tibble
- active_vessels_strategy
The strategy to associate the active vessels to the effort based on time. Active vessels period does not match necessarily the periods of data (effort, landings), and can be reported either by year or by year/month. This parameter let decide which methodology should be used to select the active vessels based on time. It can be either "latest" (taking the latest period), "closest" ie the closest active vessels in time, after or before the data period. In case 2 periods before/after are equally closer, the latest in time before the data period will be taken.