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Changelog

Source: NEWS.md

animetric (development version)

Removed

  • mean_angle() and median_angle() are removed. Use anicore::circ_mean() and anicore::circ_median(), which are attached by library(animovement) (animovement/anicore#147). The circular statistics live in one place now, and these were the two that had drifted: mean_angle() duplicated circ_mean() exactly, and median_angle() was not a circular median at all.

    median_angle() took the median of the sine and cosine components, which is not rotation-equivariant — rotating every angle in a sample by the same amount moved its answer by a different amount, so the result depended on where the circle was cut. anicore::circ_median() is Fisher’s circular median and does not have that defect, so it is a replacement that returns different numbers. Any stored values computed with median_angle() were frame-dependent.

Fixed

  • The windowed straightness of add_tortuosity() is NA for a window that holds a missing position (#108). The distance travelled left out the steps to and from the missing position while the displacement still spanned the gap, so the straightness could exceed 1. calculate_tortuosity(), which is deprecated, keeps its old output.

  • calculate_kinematics() gives correct results for polar, cylindrical and spherical input stored in degrees. It converts such input to Cartesian with anispace’s map_to_*(), which read every angle as radians until animovement/anispace#47, so phi = 90 was taken as 90 radians. animetric now requires anispace 0.3.0.9005, which has the fix.

  • heading from calculate_kinematics() is pi for movement along -x, where it used to be rewritten to 0 — the opposite direction (#69). The rewrite fired whenever v_y was exactly zero, which integer-pixel tracking produces routinely, so a trajectory along -x picked up 180-degree jumps that showed as spikes in angular_velocity and angular_acceleration and as turning in angular_path_length that never happened. heading is now NA where speed is zero, since a stationary animal has no direction of travel; before, it read as 0, or as pi when the velocity was a negative zero.

  • angular_path_length from calculate_kinematics() starts at 0 (#68). When the first heading was negative it started at 2 * abs(heading) and carried that offset along the whole trajectory, so a straight line at a heading of -1 reported two radians of turning. summarise_tortuosity() takes the difference between the last and first values, so its total_angular_path_length was not affected. Turning made while the animal is stopped (where heading is NA) is counted when it moves off again.

  • calculate_kinematics(), calculate_tortuosity(), summarise_kinematics() and summarise_tortuosity() read the axes and the index from the frame’s declared variables, so they work on frames whose columns are not called x, y, z and time (#81). They used to stop with “Column x not found”. Velocity and acceleration components are named by axis role (v_x, a_y, …) whatever the input columns are called. 1D frames get translational kinematics and tortuosity too; calculate_kinematics() used to return them unchanged. The 2D and 3D code paths are now one implementation, with turning angles from anicore::angle_between(). The only change in output is that 3D windowed tortuosity is NA at the first row where the window is incomplete, as it already was in 2D; the old 3D code filled the missing start of the window with the first position.

  • Angular measures are returned in the frame’s declared unit_angle (#80). A frame declared in degrees used to get heading, angular_velocity, angular_acceleration, angular_path_length and the heading summaries in radians, still labelled as degrees, so anything that trusted the metadata was off by a factor of 180/pi. calculate_kinematics(), summarise_kinematics() and summarise_tortuosity() now report them in degrees for such frames, with no extra step. Radian frames are unchanged. The documentation now also says which way signed angles run: they follow the frame’s own axes, counter-clockwise when y points up, as aniread leaves image data.

  • calculate_nnd() keeps the input’s metadata, such as sampling_rate, and works on frames whose axis columns have custom names. It used to rebuild its result by re-detecting the columns, which dropped both.

Added

  • add_kinematics() and summarise_path() take min_step, the shortest step whose direction counts (#104). A point that barely moves takes its direction from tracking noise, which swings at random from frame to frame and was all counted as turning. Below min_step, course is NA and the row adds nothing to turning_speed, turning_rate, turning_acceleration, cumulative_turning or total_turning; a turn made in the meantime is counted once, when the animal moves off. The default, "auto", is three times the positional noise estimated for each trajectory, and at most half its median step. min_step = 0 counts every direction, as calculate_kinematics() did. On the SLEAP sample, cleaned and smoothed as in the Get Started guides, the centre’s total_turning falls from about 356,000 to 243,000 degrees.

  • compute_min_step() returns the threshold that min_step = "auto" chooses for each trajectory, with the positional noise it is estimated from, in the frame’s spatial unit (#111). It is computed by the same code as in add_kinematics(), so it can be reported, compared with a known tracking precision, or passed back as min_step, for example to use one threshold for every trajectory. It is experimental, like min_step.

  • summarise_path() and add_tortuosity() compute sinuosity and e_max from the path rediscretised to a constant step length, as Benhamou (2004) defines sinuosity (#104). Jitter while an animal is still gives no steps, so it no longer dominates them. A window of add_tortuosity() in which the animal moved less than a step has NA.

  • summarise_path() and add_tortuosity() take step_length, the step the path is rediscretised at for sinuosity and e_max, in the frame’s spatial unit (#114). The default, "auto", is each trajectory’s own step as before; a number rediscretises every trajectory at that step, so that their sinuosity can be compared at one scale. It is experimental.

  • add_orientation() declares which way a body faces from where its points are (#97):

    • 2D: heading, the direction from from to to.
    • 3D: a unit quaternion (qw, qx, qy, qz), with a third point, plane, to fix the roll. Any point off the from-to line will do.
    • Across the body: perpendicular = TRUE handles axes that run across the body, such as right eye to left eye.
    • Where it goes: attach_to puts the orientation on chosen members, so a head and a body orientation can share the one declared column.

    Once declared, the orientation is a proper where variable, which anispace’s egocentric transform can align by. Needs anispace 0.3.0.9006 (quat_from_vectors()).

Changed

  • add_nnd() replaces calculate_nnd() (#109). It returns the frame with nearest-neighbour columns added, so it joins the add_*() family. compute_nnd() keeps its name, as it returns values. On the way:

    calculate_nnd() add_nnd()
    nnd_<across> (e.g. nnd_individual) nnd_<n>_<across> (e.g. nnd_1_individual)
    nnd_<variable> (e.g. nnd_keypoint) nnd_<n>_<variable> (e.g. nnd_1_keypoint)
    nnd_distance nnd_<n>_distance
    • Every column carries the neighbour rank n, 1 included, so the nearest and second-nearest neighbours sit side by side: add_nnd(n = 1) |> add_nnd(n = 2). It used to stop with “Names must be unique”. The names split unambiguously with ^nnd_(\d+)_(.+)$, even when the column after the rank has underscores in it. Calling it again with the same n says which columns are already there.
    • n must be a single whole number of 1 or more.
    • The deprecated keypoint_neighbour argument is not carried over; use neighbour = list(keypoint = ...).

  • add_kinematics() and add_tortuosity() replace calculate_kinematics() and calculate_tortuosity(), with the same arguments (#103). Functions that return the frame with something added now all start with add_. Some columns are renamed on the way:

    Function Old New
    add_kinematics() path_length cumulative_distance
    add_tortuosity() straightness straightness_11
    add_tortuosity() sinuosity sinuosity_11
    add_tortuosity() emax e_max_11
    • cumulative_distance is the running total of distance travelled, and pairs with cumulative_turning. acceleration keeps its name, and its documentation now says what it is: the signed rate of change of speed along the path, not the size of the acceleration vector (a_x, a_y).
    • add_tortuosity() names its columns with the window width, 11 being the default, and adds only those three. calculate_tortuosity() also added every kinematic column when the frame had none. The width in the name keeps the windowed measures apart from the whole-path ones of summarise_path(), and lets several widths sit side by side.
    • summarise_aniframe() summarises the windowed measures at every width present (median_straightness_11, …), as well as the unsuffixed columns of calculate_tortuosity().

  • summarise_aniframe(), add_orientation() and the vertical argument of calculate_kinematics() are marked experimental (animovement/.github#46). They are new designs that have not been used in anger yet, so they may still change without a deprecation cycle; anything without a badge is stable, and changes only through one. summarise_aniframe() has open design questions (#91, #92, #22), the first uses of add_orientation() are still being designed (#25, #85), and vertical may come to default to a vertical declared in the frame’s metadata (animovement/anicore#172).

  • The summaries are reorganised into two functions, by what they summarise (#58). Sliding windows stay in add_tortuosity(); both summaries cover each group’s whole time range.

    • summarise_aniframe() summarises the distribution of per-row measures, with one row per group and any grouping allowed. It is now an S3 generic:
      • anipoints: speed, acceleration, the turning measures, course and elevation, the windowed measures of add_tortuosity(), confidence, and a declared yaw as *_heading.
      • anisegments: length.
      • anijoints: angle.
      Angles (course, yaw, joint angles) get circular statistics, reported in the frame’s unit_angle. cols = picks the measures. It no longer needs add_kinematics() to have been run: it summarises whichever measures the frame has.
    • summarise_path() measures each trajectory as a whole: total_distance, total_turning, net_displacement, straightness, sinuosity and e_max. It works on any anipoint in any coordinate system, computing what it needs from the positions, and needs one trajectory per group.

    median_straightness_11 from summarise_aniframe() is the typical straightness over windows; straightness from summarise_path() is how direct the whole route was.

  • Deprecated:

    Each deprecated call returns exactly what it did before. They will be removed after the next release.

  • add_point() and compute_point() replace add_centroid() and compute_centroid() (#94). They derive a new member of an identity level at each moment, as before, and method now chooses how:

    • "centroid", the mean (the default, and what the old functions did);
    • "median", robust to a stray keypoint;
    • "weighted", weighted by confidence;
    • a function of your own, e.g. \(x) mean(x, trim = 0.1).

    A declared orientation is derived for the new member too: the circular mean of yaw, or the mean quaternion in 3D. It used to be left NA. add_centroid() and compute_centroid() are deprecated, and return exactly what they did.

  • The aniframe_kin class is retired (#58). calculate_kinematics() returns a plain anipoint. The class only labelled a frame as having been through calculate_kinematics(), recorded nothing about its columns, and survived select(-speed). is_aniframe_kin() is deprecated; check for the columns you need instead. Declaring derived columns in anicore’s metadata is the planned replacement (animovement/anicore#174).

  • calculate_kinematics() gives turning measures for 3D data too (#63). Every 3D frame gets turning_speed (how fast the direction of travel turns, in any direction) and cumulative_turning, and calculate_kinematics(data, vertical = "z") adds course and course_unwrapped in the horizontal plane, course_elevation (the angle of travel above it), and the signed horizontal turning_rate and turning_acceleration. The new vertical argument names the axis that points up in the world, with a minus sign when it points down ("-y"); the frame’s axis_directions cannot supply it, since they are relative to the camera (animovement/anicore#172 proposes declaring it). Course counts about the vertical by the right-hand rule. The 3D turning speed is the angle between the velocities either side of each row over the time between them, so it has no wrap at +/-pi and no singularity when travel is vertical; 2D results are unchanged. summarise_kinematics() and summarise_tortuosity() summarise the new columns, and total_turning is now reported for 3D.

  • Breaking: the velocity-derived angular columns are renamed to say they describe the path, not the body (#70). Course is the direction of travel and turning rate is how fast it changes, while heading and angular velocity are where the animal faces and how fast that turns. They differ for any animal that does not move nose-first, and the orientation names are kept free for body orientation once anicore records it (animovement/anicore#46).

    Old New
    heading course
    heading_unwrapped course_unwrapped
    angular_velocity turning_rate
    angular_speed turning_speed
    angular_acceleration turning_acceleration
    angular_path_length cumulative_turning

    The summaries follow: median_heading, mad_heading, mean_heading and sd_heading become *_course, *_angular_speed, *_angular_velocity and *_angular_acceleration become *_turning_speed, *_turning_rate and *_turning_acceleration, and summarise_tortuosity()’s total_angular_path_length becomes total_turning. Values are unchanged.

  • data.table is now a hard dependency (#27). calculate_tortuosity() cannot work without it, so the first call on a fresh install used to stop and offer to install it.

  • Works with anicore’s anipoint class and rebuilt accessor API (animovement/anicore#154). calculate_kinematics() returns a frame of class c("aniframe_kin", "anipoint", "aniframe", ...).

  • The circular summaries in summarise_kinematics() come from anicore, and the circular package is no longer needed at all (animovement/anicore#147). It was a soft dependency behind a check_installed() prompt, so the first call to summarise_kinematics() on a fresh install used to stop and ask to install a package — for two columns of the summary table.

  • mean_heading is reported in [0, 2*pi), like median_heading already was. It previously came back in (-pi, pi], so the two summaries of the same column disagreed about where the circle starts; near +/-pi that showed up as a mean of -3.13 beside a median of 3.15. Both now use the range anicore::wrap_angle() gives by default. The direction is unchanged — only how it is written down.

Deprecated

Fixed

  • median_heading could be 180 degrees wrong, and is now correct (animovement/anicore#147). Where two directions tie for the circular median, the old implementation averaged them arithmetically — it read the tied pair out of an undocumented attribute of circular::median.circular()’s return value and called mean() on it. When the tie straddles zero, the arithmetic mean of the two is their antipode. Headings tied at 0.1 and 5.8 radians gave 2.95 radians, or 169 degrees, where the answer is 349 degrees:

    # the two tied directions, and what each way of averaging them gives
#   arithmetic: (0.1 + 5.8) / 2 = 2.95   -> 169 degrees, the antipode
#   circular:   anicore::circ_median()   -> 349 degrees

    Nothing signalled it: no NA, no warning, and a plausible direction. Heading distributions straddle zero routinely, so this was not a corner case. anicore::circ_median() averages tied directions on the circle, and a grid search over the definition — the direction minimising the summed angular distance — confirms which of the two is the median. Any stored median_heading may need recomputing.

  • sd_heading is 0 rather than NaN when the heading never changes. circular::sd.circular() returns NaN there, because the resultant length of a constant sample can land above 1 in floating point; anicore’s circ_sd() clamps it. A keypoint that does not move produces exactly this (animovement/anicore#147).

animetric 0.5.0 (2026-08-28)

Changed

  • The minimum anicore is 0.8.0, the first version published under that name — the dependency was renamed without a version constraint, so nothing recorded that a pre-rename aniframe will not do.

  • The core data structures come from anicore, which is what the aniframe package was renamed to in its 0.8.0 (animovement/anicore#84). The aniframe class keeps its name; only the package providing it changed.

  • The calculate_kinematics(), calculate_nnd() and calculate_tortuosity() examples run rather than sitting in \dontrun{}. Each builds its own frame with anicore::example_aniframe(); they were wrapped because they referred to an undefined data, so they had never been checked against the functions they document.

  • calculate_nnd() reads the columns it needs from the aniframe’s metadata, and takes the identity roles explicitly (#37). It previously hard-coded individual, c("session", "trial", "time"), keypoint and x/y/z, consulting the metadata for none of them.

    That was already producing wrong numbers: observation joined variables_when in aniframe 0.6.0, but the hard-coded context list never picked it up, so multi-clip data was pooled and each animal could be matched to one in a different clip — silently, and with a plausible-looking distance.

    across names the column whose value must differ (required — nothing is inferred), within names columns that must match on top of the temporal context, and focal / neighbour restrict which points are measured from and to. Being independent, they express asymmetric questions:

    # whose neck is my head nearest to?
data |> calculate_nnd(
  across = "individual",
  focal = list(keypoint = "head"),
  neighbour = list(keypoint = "neck")
)

# nearest keypoint within each animal
data |> calculate_nnd(across = "keypoint", within = "individual")

    Existing calls need across = "individual" added. keypoint_neighbour still works, with a deprecation warning, and maps to neighbour = list(keypoint = ...).

  • Frames identified by track or subject rather than individual now work, as do multi-observation frames. Polar, cylindrical and spherical frames error with a pointer to anispace::map_to_cartesian() rather than silently measuring in mixed units.

  • compute_nnd() takes across, is_focal, is_candidate and labels in place of individual, keypoint and keypoint_neighbour, mirroring the generalisation above. Its result names the ranked column (nnd_across) which calculate_nnd() renames.

  • summarise_keypoints() is renamed add_centroid(), and takes across to choose the level it collapses (#47). The old name is gone rather than deprecated — it has not been in a release, so nothing can be depending on it. The old name said summarise_, which in this package means collapsing a frame to summary rows — this appends them. It also named the keypoint level, which is only one of the levels a frame can be summarised across.

    across names the identity variables to collapse, so the same question can be asked at any scale. On pose data for a team:

    add_centroid(af, across = "keypoint")                  # each player's own centre
add_centroid(af, across = "individual")                # one centre per keypoint, across players
add_centroid(af, across = c("individual", "keypoint")) # the point the whole team occupies

    It is not guessed. variables_what is documented coarse to fine, but nothing enforces that and attributes like sex or treatment do not nest at all, so a frame declaring more than one identity variable has to be told which to collapse (animovement/anicore#140, animovement/anicore#141). A frame declaring one is unambiguous and needs no argument.

    A collapsed level that did not actually vary keeps its value rather than taking the summary’s name — an individual’s strain is still its strain, since nothing was averaged over it.

    Only identity variables can be collapsed. Collapsing the index or a temporal variable averages over time, which is what the summarise_*() family does.

  • compute_centroid()’s include_keypoints, exclude_keypoints and centroid_name are renamed include, exclude and name, and it takes the same across (#47). add_area is gone from the summary function: it was never implemented, and area is a different shape of answer that will arrive as its own function rather than a flag.

Fixed

  • calculate_kinematics(), calculate_tortuosity() and summarise_tortuosity() refuse a frame whose grouping pools several trajectories, rather than answering wrongly (#54). Speed and path length come from successive rows within a group, so a group has to hold one position per moment. Regrouping an aniframe coarsely — every keypoint of an animal together, say — made the distance between keypoints count as movement:

    # two keypoints 100 apart, each drifting 1 per frame
calculate_kinematics(af)                      # mean speed 1, correct
calculate_kinematics(regrouped_by_individual) # mean speed 2.7, silently

    Path length accumulates the same way, and summarise_tortuosity() takes its last value minus its first — across concatenated trajectories that is a number describing nothing, and it was inflating totals about threefold.

    Regrouping itself is still allowed; anicore already warns that a frame’s grouping and its declaration then disagree. This is narrower and firmer: these computations have a precondition, and the error says how to summarise more coarsely — summarise at the declared grouping first, then combine those results.

  • compute_centroid() carries the source frame’s metadata into its result (#38, #47). Sampling rate, units and the rest were dropped, so a centroid arrived claiming to know nothing about the recording it came from.

  • A centroid no longer gains a confidence column on frames that do not track one (#47).

Removed

  • The re-exports of as_aniframe(), is_aniframe(), ensure_is_aniframe(), deg_to_rad(), rad_to_deg(), wrap_angle(), unwrap_angle(), calculate_angular_difference() and diff_angle(). Calls to these through animetric:: need repointing at anicore:: or anispace::. animetric still uses them internally — it just has no reason to publish another package’s interface as its own, which left the same function documented in two places and animetric’s exports growing whenever anicore’s did.

animetric 0.4.0 (2026-08-18)

Changed

  • Removed the aniframe_kin2d and aniframe_kin3d classes. calculate_kinematics() set them, but nothing ever read them — no predicate, no method, no test in any package — and the dimensionality they encoded already lives in the coordinate_system metadata field. Kinematics output still carries aniframe_kin, which is what the summarise_*() functions dispatch on.

Fixed

  • calculate_nnd() checks that the individual and keypoint columns exist before reading them. An absent column was reported as an all-NA one, and every call warned on the way. Surfaced by aniframe 0.7.0, which no longer adds a keypoint column beside an existing identity.

animetric 0.3.2

Changed

  • Requires aniframe 0.4.1.

animetric 0.3.1

Added

Fixed

animetric 0.3.0 (2025-12-04)

The calculate_*() and summarise_*() families are reworked, tortuosity metrics arrive, and with calculate_nnd() the package gains its first social metric.

Added

  • calculate_nnd() and compute_nnd() compute nearest-neighbour distance through a time series — the first collective metric in the package.

Removed

  • calculate_kinematics_2d(), calculate_kinematics_3d(), calculate_tortuosity_2d() and calculate_tortuosity_3d(). calculate_kinematics() and calculate_tortuosity() branch on dimensionality themselves, from the frame’s coordinate_system.

animetric 0.2.1

Changed

  • Spatial transformations are taken from anispace, following their move out of aniframe.

animetric 0.2.0

The package takes its present shape: kinematics, path complexity, angles and summaries.

Added

animetric 0.1.0

First commit. animetric computes movement metrics from an aniframe — kinematics, path complexity and summaries over a trajectory.