readCountsData: Convert Accelerometer Output Data to a Correct Data Format

Description

This function converts accelerometer output data to a correct data format to classify wear and nonwear time using wearingMarking. This function can accept accelerometer output data with various epochs (for example, 1-sec, 10-sec or 1-min). If accelerometer data are collected with three axes, it creates vector magnitude (vm).

Usage

readCountsData(filename, ctPerSec, mode = 0)

Arguments

filename

A filename of accelerometer output to be read.

ctPerSec

Data collection epoch. This argument tells the program the number of counting will be performed in every second. For examples: for 1-sec epoch data, set ctPerSec = 1; for 10-sec epoch data, set ctPerSec = 1/10; for 1-min epoch data, set ctPerSec = 1/60.

mode

The mode of the ActiLife dat file. Defaults to 0, and should be listed in the file header.

Value

a data frame with the correct format (TimeStamp, counts) to be used for wearingMarking.

References

Choi L, Liu Z, Matthews CE, Buchowski MS. Validation of accelerometer wear and nonwear time classification algorithm. Med Sci Sports Exerc. 2011 Feb;43(2):357-64.

Examples

Run this code

# NOT RUN {
###############################################################################
## Read accelerometer output and convert to a correct format (TimeStamp, counts)
## Suppose "rawActigraphOutput.dat" is an Actigraph output with header as follows:
###############################################################################
## --- Data File Created By ActiGraph GT1M ActiLife v4.4.1 Firmware v7.2.0 ---
## Serial Number: LYN2B21080027
## Start Time 16:15:00
## Start Date 6/16/2010
## Epoch Period (hh:mm:ss) 00:00:01
## Download Time 09:50:23
## Download Date 6/22/2010
## Current Memory Address: 983038
## Current Battery Voltage: 4.01     Mode = 0
## --------------------------------------------------
###############################################################################
## This raw data with 1-sec epoch can be converted to a correct data format to
## classify wear and nonwear time using "wearingMarking" by the following code:

# }
# NOT RUN {
mydata1s = readCountsData("rawActigraphOutput.dat", ctPerSec=1)
# }