Translate coordinates in Cartesian space

Moves the origin: to a fixed offset, or onto a member of the frame's identity — a keypoint, an animal, or whatever level the frame declares. Translating onto a member is how coordinates are made relative to the subject rather than the arena.

Usage

translate_coords(data, to = NULL, level = NULL, by = NULL)

Arguments

data

An aniframe in a Cartesian coordinate system.

to

A value of level to place at the origin. All other coordinates become relative to it.

level

The identity variable to is a member of. Defaults to the frame's only one; a frame declaring several has to be told.

by

Named numeric giving a fixed offset per axis role, e.g. c(x = 100, y = 50). The offset moves the origin, as to does, so the coordinates shift by the negative of it: c(x = 100) moves every point 100 to the left. Mutually exclusive with to.

Value

An aniframe with translated coordinates.

See also

Other coordinate transforms: rotate_coords(), transform_to_egocentric()

Examples

af <- anicore::example_aniframe(n_obs = 3, n_individuals = 1, n_keypoints = 3)

# Everything becomes relative to the head, which sits at the origin
translate_coords(af, to = "head", level = "keypoint")
#> # Individuals: 1
#> # Keypoints:   head, neck, shoulder_right
#> # Sessions:    1
#> # Trials:      1
#>   individual keypoint       session trial  time      x      y confidence
#>        <int> <fct>            <int> <int> <int>  <dbl>  <dbl>      <dbl>
#> 1          1 head                 1     1     1  0      0          0.700
#> 2          1 head                 1     1     2  0      0          0.746
#> 3          1 head                 1     1     3  0      0          0.853
#> 4          1 neck                 1     1     1 -0.159  1.63       0.226
#> 5          1 neck                 1     1     2 -1.79  -2.67       0.534
#> 6          1 neck                 1     1     3  0.373 -0.987      0.476
#> 7          1 shoulder_right       1     1     1  0.291  2.56       0.379
#> 8          1 shoulder_right       1     1     2 -1.13  -0.855      0.890
#> 9          1 shoulder_right       1     1     3  0.813 -0.391      0.599

# Or move the origin by a fixed amount, which shifts the coordinates the
# other way: x becomes x - 100
translate_coords(af, by = c(x = 100, y = 50))
#> # Individuals: 1
#> # Keypoints:   head, neck, shoulder_right
#> # Sessions:    1
#> # Trials:      1
#>   individual keypoint       session trial  time      x     y confidence
#>        <int> <fct>            <int> <int> <int>  <dbl> <dbl>      <dbl>
#> 1          1 head                 1     1     1 -101.  -51.5      0.700
#> 2          1 head                 1     1     2  -99.2 -48.5      0.746
#> 3          1 head                 1     1     3  -99.9 -49.6      0.853
#> 4          1 neck                 1     1     1 -101.  -49.9      0.226
#> 5          1 neck                 1     1     2 -101.  -51.1      0.534
#> 6          1 neck                 1     1     3  -99.5 -50.6      0.476
#> 7          1 shoulder_right       1     1     1 -101.  -48.9      0.379
#> 8          1 shoulder_right       1     1     2 -100.  -49.3      0.890
#> 9          1 shoulder_right       1     1     3  -99.1 -50.0      0.599