mt_scale_trajectories centers and / or standardizes selected
trajectory variables within or across trajectories.
mt_scale_trajectories(
data,
use = "trajectories",
save_as = use,
var_names,
center = TRUE,
scale = TRUE,
within_trajectory = FALSE,
prefix = "z_",
transform = NULL
)a mousetrap data object created using one of the mt_import
functions (see mt_example for details). Alternatively, a trajectory
array can be provided directly (in this case use will be ignored).
a character string specifying which trajectory data should be used.
a character string specifying where the resulting trajectory data should be stored.
character vector giving the labels of the to be standardized variables.
logical specifying whether variables should be centered (i.e.,
mean = 0). Can be a logical vector, in which case the values of
scale are mapped to the variables specified in var_names.
logical or numeric specifying the scaling of the variables. When
logical, scale = TRUE normalizes the trajectory variable to sd = 1,
whereas scale = FALSE leaves the variable on its original scale. When
numeric, the trajectory variables are scaled by (i.e., divided by) the
specific value in scale. Can also be a numeric vector, in which case the
values of scale are mapped to the variables specified in
var_names.
logical specifying whether trajectory variables
should be scaled within or across trajectories. If within_trajectory
== TRUE, scaling trajectories to mean = 0 and sd = 1 means that every to
be standardized trajectory variable will have mean = 0 and sd = 1. If
within_trajectory == FALSE (the default), mean = 0 and sd = 1 are
only true in the aggregate (i.e., across all trajectories). Can be a
logical vector, in which case the values of scale are mapped to the
variables specified in var_names.
character string added to the names of the new standardized
variables. If prefix = "", the original variables will be
overwritten.
function that takes a numeric matrix as argument and returns
a numeric matrix of same size with transformed values. If NULL the
original values are passed on to standardization.
A mousetrap data object (see mt_example) with an additional
variable containing the standardized trajectory variable added to the
trajectory array). If the trajectory array was provided directly as
data, only the trajectory array will be returned.
mt_standardize for standardizing mouse-tracking measures per level of other variables.
# Calculate derivatives
mt_example <- mt_derivatives(mt_example)
# Standardize velocity across trajectories
mt_example <- mt_scale_trajectories(mt_example,var_names = "vel")