Extract sightings and associated information from processed DAS data
das_sight(x, ...)# S3 method for data.frame
das_sight(x, ...)
# S3 method for das_df
das_sight(
x,
return.format = c("default", "wide", "complete"),
return.events = c("S", "K", "M", "G", "s", "k", "m", "g", "t", "p", "F"),
...
)
Data frame with 1) the columns from x, excluding the 'Data#' columns,
and 2) columns with sighting information extracted from 'Data#' columns.
See das_format_pdf for more information the sighting information.
If return.format is "default", then there is one row for each species of each sighting event;
if return.format is "wide", then there is one row for each sighting event;
if return.format is "complete", then there is one row for every
group size estimate for each sighting event (excluding sperm whale "C" events - see the Details section).
The format-specific columns are described in their respective sections. The following sighting information columns are included in all return formats:
| Sighting information | Column name | Notes |
| Sighting number | SightNo | Character |
| Subgroup code | Subgroup | Character |
| Daily sighting number | SightNoDaily | See below |
| Observer that made the sighting | Obs | |
| Standard observer | ObsStd | Logical; TRUE if Obs is one of ObsL, Rec or ObsR, and FALSE otherwise |
| Bearing to the sighting | Bearing | Numeric; degrees, expected range 0 to 360 |
| Number of reticle marks | Reticle | Numeric |
| Distance (nautical miles) | DistNm | Numeric |
| Sighting cue | Cue | |
| Sighting method | Method | |
| Photos of school? | Photos | |
| Birds present with school? | Birds | |
| Calibration school? | CalibSchool | |
| Aerial photos taken? | PhotosAerial | |
| Biopsy taken? | Biopsy | |
| Probable sighting | Prob | Logical indicating if sighting has associated ? event; NA for non-S/K/M/G events |
| Number of species in sighting | nSp | NA for non-S/K/M/G events |
| Mixed species sighting | Mixed | Logical; TRUE if nSp > 1 |
| Group size of school - best estimate | GsSchoolBest | See below |
| Group size of school - high estimate | GsSchoolHigh | See below |
| Group size of school - low estimate | GsSchoolLow | See below |
| Course (true heading) of school at resight | CourseSchool | NA for non-s/k/m events |
| Presence of associated JFR | TurtleJFR | NA for non-"t" events; JFR = jellyfish, floating debris, or red tide |
| Estimated turtle maturity | TurtleAge | NA for non-"t" events |
| Perpendicular distance (km) to sighting | PerpDistKm | Calculated via (abs(sin(Bearing*pi/180) * DistNm) * 1.852) |
SightNoDaily is a running count of the number of S/K/M/G sightings that occurred on each day. It is formatted as 'YYYYMMDD'_'running count', e.g. "20050101_1".
The GsSchoolBest, GsSchoolHigh, and GsSchoolLow columns are either:
1) the arithmetic mean across observer estimates, for the "default" and "wide" formats, or
2) the individual observer estimates, for the "complete" format.
Note that for non-"complete" formats, na.rm = TRUE is used when calculating the mean,
and thus blank elements of estimates (but not the whole incomplete estimate) are ignored.
To convert the perpendicular distance back to nautical miles, one would divide PerpDistKm by 1.852
an object of class das_df,
or a data frame that can be coerced to class das_df
ignored
character; can be one of "default", "wide", "complete", or any partial match thereof (case sensitive). Formats described below
character; event codes included in the output. Must be one or more of: "S", "K", "M", "G", "s", "k", "m", "g", "t", "p", "F" (case-sensitive). The default is all of these event codes
This output data frame contains 'long' sighting data, meaning there is one row for each species of each sighting event.
The GsSp... columns are calculated as follows:
for each species and for each observer estimate, the best/high/low school size estimate is multiplied by the applicable species percent estimate.
The values are grouped by species and then averaged to get single GsSpBest, GsSpHigh, and GsSpLow values for each species.
(using mean with na.rm = TRUE)
Sighting information columns/formats present specifically in the "default" format output:
| Sighting information | Column name | Notes |
| Species code | SpCode | Boat type or mammal, turtle, or pinniped species codes |
| Probable species code | SpCodeProb | Probable mammal species codes; NA if none or not applicable |
| Group size of species - best estimate | GsSpBest | The product of the arithmetic means of GsSchoolBest and the corresponding species percentage |
| Group size of species - high estimate | GsSpHigh | The product of the arithmetic means of GsSchoolHigh and the corresponding species percentage |
| Group size of species - low estimate | GsSpLow | The product of the arithmetic means of GsSchoolLow and the corresponding species percentage |
Note that for the above calculations,
the GsSchoolX value and corresponding species percentages were each
averaged across observers, using na.rm = TRUE,
before being multiplied to calculate GsSpX. For example, in the workflow:
GsSpBest1 = mean(.data$Data2, na.rm = TRUE) * mean(.data$Data5, na.rm = TRUE)
The "wide" and "complete" options have very similar columns in their output date frames.
There are two main differences: 1) the "wide" format has one row for each sighting event,
while the complete format has a row for every observer estimate for each sightings, and thus
2) in the "wide" format, all numeric information for which there are multiple observer estimates
(school group size, species percentage, etc.) are averaged across estimated via
an arithmetic mean (using mean with na.rm = TRUE)
With these formats, note that the species/type code and group size for turtle, pinniped, and boat sightings are in their own column
Sighting information columns present in the "wide" and "complete" format outputs:
| Sighting information | Column name | Notes |
| Observer code - estimate | ObsEstimate | See below |
| Species 1 code | SpCode1 | |
| Species 2 code | SpCode2 | |
| Species 3 code | SpCode3 | |
| Species 4 code | SpCode4 | |
| Species 1 probable code | SpCodeProb1 | Extracted from '?' event |
| Species 2 probable code | SpCodeProb2 | Extracted from '?' event |
| Species 3 probable code | SpCodeProb3 | Extracted from '?' event |
| Species 4 probable code | SpCodeProb4 | Extracted from '?' event |
| Percentage of Sp 1 in school | SpPerc1 | |
| Percentage of Sp 2 in school | SpPerc2 | |
| Percentage of Sp 3 in school | SpPerc3 | |
| Percentage of Sp 4 in school | SpPerc4 | |
| Group size of species 1 | GsSpBest1 | Present in "wide" output only; see below |
| Group size of species 2 | GsSpBest2 | Present in "wide" output only; see below |
| Group size of species 3 | GsSpBest3 | Present in "wide" output only; see below |
| Group size of species 4 | GsSpBest4 | Present in "wide" output only; see below |
| Turtle species | TurtleSp | NA for non-"t" events |
| Turtle group size | TurtleGs | NA for non-"t" events |
| Was turtle captured? | TurtleCapt | NA for non-"t" events |
| Pinniped species | PinnipedSp | NA for non-"p" events |
| Pinniped group size | PinnipedGs | NA for non-"p" events |
| Boat or gear type | BoatType | NA for non-"F" events |
| Number of boats | BoatGs | NA for non-"F" events |
ObsEstimate refers to the code of the observer that made the corresponding estimate. For the "wide" format, ObsEstimate is a list-column of all of the observer codes that provided an estimate. Also in the "wide" format, the GsSpBest# columns are the product of the means of GsSchoolBest and the corresponding species percentage (see the Default section for calculation details). These numbers, 1 to 4, correspond to the order of the data as it appears in the DAS file
DAS events contain specific information in the 'Data#' columns,
with the information depending on the event code for that row.
The output data frame contains columns with this specific information
extracted to dedicated columns as described below.
This function recognizes the following types of sightings:
marine mammal sightings (event codes "S", "K", or "M"),
marine mammal resights (codes "s", "k", "m"),
marine mammal subgroup sightings (code "G"),
marine mammal subgroup resights (code "g"),
turtle sightings (code "t"),
pinniped sightings (code "p"),
and fishing vessel sightings (code "F").
Warnings are printed if all S, K, M, and G events (and only these events) are not
followed by an A event and at least one numeric event.
See das_format_pdf for more information about events and event formats.
Of specific note - sperm whale sightings (species code 046) often contain additional estimates
recorded as "C" events immediately following the S, A, and numeric events.
Because these estimates are recorded as"C" events, they are NOT included in the
das_sight calculations or output for any return.format
The return.events argument simply provides a shortcut for
filtering the output of das_sight by event codes
Abbreviations used in output column names: Gs = group size, Sp = species, Nm = nautical mile, Perc = percentage, Prob = probable, GsSchool = school-level group size info
This function makes the following assumptions, and alterations to the raw DAS data:
"A" events immediately following an S/K/M/G event have the same sighting number (Data1 value) as the S/K/M/G event
The 'nSp' column is equivalent to the number of non-NA values across the
'Data5', 'Data6', 'Data7', and 'Data8' columns
for the pertinent "A" event
The following data are coerced to a numeric using
as.numeric:
Bearing, Reticle, DistNm, Cue, Method,
species percentages, and group sizes (including for t, p, and F events).
Note that if there are any formatting errors and these data are not numeric,
the function will likely print a warning message
The values for the following columns are capitalized using
toupper:
'Birds', 'Photos', 'CalibSchool', 'PhotosAerial', 'Biopsy',
'TurtleAge', and 'TurtleCapt'
y <- system.file("das_sample.das", package = "swfscDAS")
y.proc <- das_process(y)
das_sight(y.proc)
das_sight(y.proc, return.format = "complete")
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