Detect Marker Label Swaps

Identifies frames where two or more marker trajectories abruptly swap positions, indicating a labelling error. Swaps are detected by velocity spikes that exceed median + 5 * MAD and show a cross-over pattern between marker pairs.

Usage

detectSwaps(pe, threshold = NULL, window = 5, assay_prefix = "position")

Arguments

pe

A PhysioExperiment with position assays.

threshold

Velocity threshold for spike detection. If NULL (default), computed as median + 5 * MAD of each marker's velocity.

window

Number of frames around a spike to check for cross-over patterns. Default 5.

assay_prefix

Prefix for position assay names. Default "position".

Value

A data.frame with columns:

frame

Frame index where the swap was detected.

marker_a

Name or index of the first marker in the swap pair.

marker_b

Name or index of the second marker.

velocity_a

Velocity of marker_a at the swap frame.

velocity_b

Velocity of marker_b at the swap frame.

confidence

Confidence score (0-1) based on how closely the cross-over distances match.

If no swaps are detected, an empty data.frame with the same columns is returned.

See also

trackMarkers(), correctSwaps()

Examples

demo <- demoMoCapData(seed = 1)
swaps <- detectSwaps(demo$mocap)
swaps
#> [1] frame      marker_a   marker_b   velocity_a velocity_b confidence
#> <0 rows> (or 0-length row.names)