Package index • distsamp

Segmenting a survey

Turning track lines into effort segments ready for Distance and dsm — each with a location, an amount of effort, and counts of what was seen along it.

cut_segments(): Cut tracks into segments
line_effort(): Effort per survey line
plan_segments(): Plan how many segments each track carries
point_to_point_effort(): Accumulate point-to-point survey effort
segment_midpoints(): Locate the along-track midpoint of each segment
segment_sightings(): Summarise sightings and conditions by segment
segment_survey(): Segment a line-transect survey
segments_as_sf(): Convert segments to spatial features
segments_wide(): Segment table with one column per species
split_tracks(): Split survey lines at breaks in effort
track_effort(): Summarise effort by continuous track
write_segments(): Write segmentation results to CSV

Distances and geometry

Perpendicular distance is what a detection function consumes. Where the survey recorded declination angles, it can be computed exactly.

circling_distance(): Perpendicular distances for sightings made while circling
cross_track_distance(): Perpendicular distance from a track to an exact sighting position
detection_data(): Build a flatfile for Distance::ds()
dist_methods(): Distance methods available
exact_distance(): Perpendicular distances from exact sighting positions
gc_bearing(): Initial great-circle bearing between positions
gc_distance(): Great-circle distance between positions
gc_interpolate(): Interpolate a position along a great circle
perp_distance(): Perpendicular distance from a declination angle
sighting_distances(): Perpendicular distances for a survey data frame
strip_distance(): Convert STRIP codes to distance intervals
track_bearing(): Local bearing of the track-line at each record

Circling and reflights

An aircraft that circles a sighting is no longer on effort. These find those passages and attach their sightings to the right segment.

attach_circling_sightings(): Attach sightings made while circling to the segment they came from
filter_days(): Keep the survey days you want to look at
flag_circling(): Flag records made while circling
reflight_summary(): How much of the survey was re-flown

Reading NARWC data

Re-exported from narwcr so a survey can be read and segmented without loading both packages.

validate_narwc(): Check survey data against the handbook and against distance sampling

Preparing and inspecting

Aerial-specific preparation, a pipeline diagnosis that reports rather than stops, and plots for looking at what came out.

crop_to_bbox(): Restrict data to a bounding box
diagnose_pipeline(): Diagnose common reasons a segmentation might be wrong before you trust it
distsamp_checks(): Checks that only matter for distance sampling
plot(<distsamp_segments>): Diagnostic plots for a segmentation
plot_survey(): Look at the survey partway through the pipeline
plot_survey_panel(): Several views of a survey, side by side
prepare_aerial(): Get a NARWC extract ready to segment