Add function to create event-based obs out of media-based observations

[damianooldoni]

The need of such a function emerged in #332.

[Rafnuss]

I've been developing such a function for my personal use (Wildlife insight media-based data). But I'm all a bit confused now on which standard I should be developing the code (camtrap-dp 0.1.6 or 1.0.1).

The function uses the assess_temporal_independence() (see #353 ) and group together media/record according to the rules (minDeltaTime_duration and deltaTimeComparedTo). I use sequenceID (or eventID?) of the first media for the sequences. I also modify the sequenceID of media, is that correct? I finally delete the non-independant observation. But because I don't have the observationStart and observationEnd (only timestamp), I'm loosing quite a lot of information here.

Let me know if you'd like to use such a function and I can make a PR. No worries if that's not the approach you were thinking of, just thought I could share this.

#' Convert media based to event-based
#'
#' @param pkg A datapackage
#' @param minDeltaTime_dur: Duration in minutes between records of the same
#'   species at the same station to be considered independent.
#' @param deltaTimeComparedTo: Character, `"lastIndependentRecord"` or
#'   `"lastRecord"`.
#'   For two records to be considered independent, must the second one be at
#'   least `minDeltaTime` minutes after the last independent record of the same
#'   species (`deltaTimeComparedTo = "lastIndependentRecord"`), or
#'   `minDeltaTime` minutes after the last record (`deltaTimeComparedTo =
#'   "lastRecord"`)?
#'   If `minDeltaTime` is 0, `deltaTimeComparedTo` should be NULL.
#' @export
media2event <- function(pkg,
                        minDeltaTime_duration = 60,
                        deltaTimeComparedTo = "lastRecord") { # or "lastIndependentRecord"

  obs <- pkg$data$observations %>%
    dplyr::group_by(.data$scientificName, .data$deploymentID) %>%
    dplyr::arrange(.data$scientificName, .data$deploymentID, .data$timestamp) %>%
    mutate(
      independent = assess_temporal_independence(
        .data$timestamp,
        minDeltaTime_dur = minDeltaTime_duration,
        deltaTimeComparedTo = deltaTimeComparedTo
      )
    ) %>%
    ungroup()

  obs$NewSequenceID <- obs$sequenceID[obs$independent][cumsum(obs$independent)]

  # Replace sequenceID in media
  pkg$data$media <- pkg$data$media %>%
    left_join(
      obs %>% select(sequenceID, NewSequenceID),
      by = "sequenceID"
    ) %>%
    mutate(sequenceID = NewSequenceID) %>%
    select(-NewSequenceID)

  # Replace sequenceID in obs and remove non-independant obs.
  pkg$data$observations <- obs %>%
    mutate(sequenceID = NewSequenceID) %>%
    filter(independent) %>%
    select(-c(independent, NewSequenceID))

  return(pkg)
}