get_dates() get date information for a BirdFlow model
Value
A data frame with columns:
- timestep
The model timestep associated with each row. Will always equal the row number.
- date
The date associated with the midpoint of the timestep
- label
The month and day based label associated with the timestep Consistent with eBird's 2022 date scheme will be one day off the
dateafter February on leap years but are still used to label timesteps. If the model was fit with an older version of ebirdst they will never be offset- julian
The Julian date (day of year) associated with the timestep center
- week
The ebirdst week number associated with the date. For full year models this is identical to
timestepbut after truncation they will differ.
Prior to BirdFlowR v. 0.1.0.9040 it returned columns:
- interval
The interval or timestep associated with each date. It will range from 1 to
n_timesteps(). With full models this is equivalent to the week of the year but with truncated models may not be.- date
The date associated with the interval's midpoint.
- midpoint, start, end
The midpoint, start, and end of each interval as a proportion of the total year that has elapsed.
- doy
The day of year associated with the midpoint of each interval.
Note
truncate_birdflow()creates models with a subset of the intervals and renames them1:[n_timesteps()]of the truncated model so if it has been usedweekandtimestepwill not have identical values.
Date scheme
In a non-leap year there are 52 weeks plus 1 day so assigning days
to weeks is a little bit arbitrary. BirdFlowR uses the same
conventions as ebirdst and eBird itself which changed
with the eBird 2022 version year. Thus for some dates the result
of lookup_timestep() will change depending on the ebird_version_year
associated with the model.
2021 date scheme (ebirdst <= 2.2021.3)
Date table is derived from
ebirdst::ebirdst_weeksand added to the model object bypreprocess_species().Julian date is converted to a proportion with
(jd - 0.5)/366.52 even ranges are assigned to 0 to 1 and the proportional date is then compared to these thresholds.
In a non-leap year two weeks have 8 days and the last week has 6.
In a leap-year two weeks have 8 days.
All other weeks have 7 days.
2022 date scheme (ebirdst >= 3.2022.0)
ebirdst dropped
ebirdst_weeksWeeks are defined by evenly spaced Julian dates (of week center) which are always
seq(4, 366, 7).Dates are assigned to the week for which the Julian date is closest.
On non-leap-years the last week has 8 days, on leap years it has 9.
All weeks but the last have 7 days.
Week labels (month and day) are assigned based on the month and day associated with the Julian week center on non-leap years regardless of whether it is a leap year. The label on leap years will thus be one day off the date of the week center for most of the year.