Sigma0 {ActivityIndex} R Documentation

## \bar{σ}_i computing using raw accelerometry data

### Description

Sigma0 computes \bar{σ}_i, which is needed for the Activity Index computing in computeActivityIndex

### Usage

Sigma0(x, hertz = 30)


### Arguments

 x A 4-column data frame containing the raw accelerometry data when the device is not worn. The 1st column has the record/index number. The 2nd to 4th columns contain the tri-axial raw acceleration. The data will be used to calculate \bar{σ}_i. hertz The sample rate of the data.

### Value

\bar{σ}_i, a numeric vector of length one.

### Examples

filename = system.file("extdata","sample_GT3X+.csv.gz",package="ActivityIndex")
hertz = res$Hertz x = res$Raw[ 1:1000, c("Time", "X", "Y", "Z")]