MEAscale {rMEA}

Scaling (and centering) of motion energy time-series

Description

Scaling (and centering) of motion energy time-series

Usage

MEAscale(mea, scale = "sd", ..., center = F, removeNA = T)

Arguments

mea

an object of class MEA or a list of MEA objects (see function readMEA)

scale

either a numeric value or a function to be applied to each motion energy time-series to calculate a scaling factor. Default is standard deviation.

...

further arguments passed to scale if it is a function.

center

either a logical value or a numeric vector of length 2 specifying separate centering values for s1 and s2.

removeNA

logical. If scale is a function, defines whether NAs be removed prior to calculating the scaling factor.

Details

If scale is a function, it is found by a call to match.fun and typically is either a function or a symbol (e.g., a backquoted name) or a character string specifying a function to be searched for from the environment of the call to apply. Note that the chosen function must return a single numeric value.

center is directly passed to scale. If center is TRUE then centering is done by subtracting the means (omitting NAs) from the motion energy time-series. If center is a numeric vector, the first value will be subtracted from s1 and the second from s2. Note: the s1 and s2 signals are scaled independently.

Value

returns the same MEA or MEAlist object, with all motion energy data rescaled

Examples

## read the first 4 minutes of the normal sample
##   (intake interviews of patients that carried on therapy)
path_normal <- system.file("extdata/normal", package = "rMEA")
mea_raw <- readMEA(path_normal, sampRate = 25, s1Col = 1, s2Col = 2,
                     s1Name = "Patient", s2Name = "Therapist",
                     idOrder = c("id","session"), idSep="_", skip=1, nrow = 6000)

## rescale by factor 0.7
mea_scaled = MEAscale(mea_raw, scale = 0.7)

## rescale with standard deviation
mea_scaled = MEAscale(mea_raw, scale = "sd", removeNA = TRUE)

## assign groups names
mea_raw <- setGroup(mea_raw, "raw")
mea_scaled <- setGroup(mea_scaled, "scaled")

## Compute ccf
mea_raw <- MEAccf(mea_raw, lagSec = 5, winSec = 60, incSec = 30, r2Z = TRUE, ABS = FALSE)
mea_scaled <- MEAccf(mea_scaled, lagSec = 5, winSec = 60, incSec = 30, r2Z = TRUE, ABS = FALSE)

## Compare the effect of scaling on ccf
MEAlagplot(mea_scaled, contrast = mea_raw)