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Flag records made while circling

Source: R/circling.R
flag_circling.Rd

Marks the records where the aircraft had left the census track to circle a sighting.

Usage

flag_circling(dat)

Arguments

dat

A data frame of NARWC survey data in survey order, with LEGTYPE and ideally LEGSTAGE and LEGNO3.

Value

dat with an integer CIRCLE column: 1 while circling, 0 otherwise.

Details

Two signals are used, either of which is sufficient:

  • LEGTYPE == 4, the line-transect "other (circling)" code (handbook 8.A.21); and

  • any record between a LEGSTAGE == 3 (break off line to circle) and the following LEGSTAGE == 4 (resume line) within the same survey line occupation (handbook 8.A.20).

The second signal matters because a survey may log positions during circling without changing LEGTYPE, and because the break-off and resume records themselves stay at LEGTYPE == 2.

References

Kenney, R.D. (2023) The North Atlantic Right Whale Consortium Database: A Guide for Users and Contributors, Version 8, sections 8.A.20 and 8.A.21. NARWC Reference Document 2023-01.

Examples

path <- system.file("extdata", "narwc-example.csv", package = "distsamp")
dat <- flag_circling(make_leg_id(read_narwc(path)))
#> `read_narwc()` renamed 2 columns:
#>   LAT_DD  -> LATITUDE
#>   LONG_DD -> LONGITUDE
#> All matched an exact entry in the alias table; `narwc_column_mapping()` returns this, and `quiet = TRUE` silences it.
sum(dat$CIRCLE)
#> [1] 5