Columns that may be carried forward, and columns that must not be
Source:R/fill.R
narwc_fill_columns.Rdnarwc_fill_columns() returns the survey-state columns fill_narwc() fills
by default: variables recorded once and left blank until they change.
Value
narwc_fill_columns() returns a character vector of fillable column
names; narwc_never_fill() returns those that are refused.
Two kinds of column
A NARWC record carries two kinds of variable, and the distinction decides whether a blank may be filled.
State persists until something changes it. LEGTYPE stays 2 until the
aircraft leaves the census line; BEAUFORT stays 3 until the sea state is
re-assessed. A blank means "as above", and filling it recovers information
that was deliberately not repeated.
Measurements belong to their own record. A position, a time, a declination angle, a species, a group size — each describes one moment. A blank means the measurement was not taken, and filling it fabricates one.
Filling a sighting column is the dangerous case
SPECCODE, NUMBER, SIGHTNO, STRIP, ANGLEL, ANGLER, S_LAT and
S_LONG are refused outright. Carrying SPECCODE and NUMBER forward would
replicate one sighting onto every subsequent record until the next sighting —
turning a single group of three right whales into hundreds — and every count
downstream would be wrong by orders of magnitude. EVENTNO, TIME,
LATITUDE, and LONGITUDE are refused for the same reason: they are what
makes a record distinct from the one before it.
Examples
narwc_fill_columns()
#> [1] "LEGTYPE" "LEGSTAGE" "LEGNO" "VISIBLTY" "BEAUFORT" "CLOUD"
#> [7] "GLAREL" "GLARER" "WX" "SURFTEMP" "ALT" "HEADING"
#> [13] "PLATFORM" "STRATUM" "BLOCK"
narwc_never_fill()
#> [1] "SPECCODE" "TAXCODE" "IDREL" "NUMBER" "NUMCALF" "SIGHTNO"
#> [7] "STRIP" "ANGLEL" "ANGLER" "S_LAT" "S_LONG" "S_TIME"
#> [13] "PHOTOS" "FILEID" "EVENTNO" "YEAR" "MONTH" "DAY"
#> [19] "TIME" "DATE" "LATITUDE" "LONGITUDE"