Pre-processed `Tracks` of 235 millipede trajectories from a visual-acuity experiment. *Cylindroiulus punctatus* individuals were placed at the centre of a cylindrical arena under bright, downwelling light, with a dark target of varying angular half-width on the arena wall, and their path tracked to test whether they oriented toward the target (object taxis). Eight stimulus conditions are represented: target half-widths of 5, 10, 15, 20, 30, 40, and 50 degrees, plus a featureless control (`arc = 0`, an angular subtense of zero).
Format
A [`Tracks`] object (44,331 observations) whose data columns include:
- trial_id
Character. Unique trial identifier.
- frame
Integer. Video frame number.
- trans_x, trans_y
Numeric. Unit-circle Cartesian coordinates.
- abs_theta
Numeric. Absolute bearing (radians).
- rel_theta
Numeric. Bearing relative to the target direction.
- rel_x, rel_y
Numeric. Target-relative unit-circle coordinates.
- arc
Ordered factor. Target half-width in degrees (`0` < `5` < `10` < `15` < `20` < `30` < `40` < `50`; 0 = control).
- type
Character. `"control"` or `"stimulus"`.
- individual
Character. Animal identifier.
Source
Behavioural experiment from Kirwan & Nilsson (2019); raw tracks produced with dtrack and normalised with radiatR. A subset of the published dataset.
Details
These tracks are a **subset** of the full experiment; see Kirwan & Nilsson (2019) for the complete dataset and trial counts.
Coordinates are normalised to the unit circle (radius = 1) and rotated so the target lies in a common reference direction; `rel_theta`, `rel_x`, and `rel_y` give the target-relative heading and position. The subject identifier is retained in the `individual` column.
The raw dtrack landmark/track text files for every trial are shipped as one archive, `inst/extdata/tracks.tar.gz` (unpack it with `untar(system.file("extdata", "tracks.tar.gz", package = "radiatR"), exdir = tempdir())`), and the trial manifest in `inst/extdata/millipede_trials.csv`, so the full import pipeline can be reproduced with [get_all_object_pos()]. See `data-raw/millipede_example.R`.
References
Kirwan, J. D., & Nilsson, D.-E. (2019). A millipede compound eye mediating low-resolution vision. *Vision Research*, 165, 36–44. doi:10.1016/j.visres.2019.09.003
Examples
cpunctatus
#> Tracks: 235 trajectories, 44331 observations
#> Columns: id='trial_id', time='frame', angle='rel_theta' (radians), x='trans_x', y='trans_y', rel_x='rel_x', rel_y='rel_y'
#> Transform steps: unit_circle_mapping
#> # A tibble: 6 × 18
#> trial_id frame x y trans_x trans_y trans_rho abs_theta rel_theta
#> <chr> <int> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 10_1_1 1 456. 372. 0.00511 0 0.00511 0 6.21
#> 2 10_1_1 2 458. 370. 0.0128 0.00770 0.0149 0.541 0.464
#> 3 10_1_1 3 456. 370. 0.00511 0.00770 0.00924 0.985 0.908
#> 4 10_1_1 4 454. 370. 0 0.00770 0.00770 1.57 1.49
#> 5 10_1_1 5 456. 377. 0.00511 -0.0153 0.0162 5.03 4.96
#> 6 10_1_1 6 459. 382. 0.0154 -0.0307 0.0343 5.18 5.10
#> # ℹ 9 more variables: rel_x <dbl>, rel_y <dbl>, video <chr>, order <chr>,
#> # vid_ord <chr>, radius <dbl>, arc <ord>, type <chr>, individual <chr>
# One heading per trial (the bearing of its furthest point from the
# origin), keeping the target half-width
hd <- derive_headings(cpunctatus, rule = "distal", carry = "arc")
table(hd$arc)
#>
#> 0 5 10 15 20 30 40 50
#> 35 31 29 30 27 37 20 26