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pawacc (version 1.2.3)

gt3xAccFile: Read a single accelerometer file

Description

This function reads Actigraph GT3X and ActiSleep accelerometer files.

Usage

gt3xAccFile(file, path, fileid, tz = "Europe/London",
	sparse = FALSE, fault = 32767)

Value

These functions return an object of two classes: accfile and additional device-specific class (i.e., gt3x).

An object of class accfile is a list containing the following components:

df

A data.frame object with accelerometer values in columns y, x, z, and steps (if present), and coded error for each accelerometer data column. See errorChk for error codes. If sparse = TRUE, all variables of the data frame df are returned as vectors of a matrix in sparse format (see as.matrix.csr for details).

info

A data.frame object with file identifier (fileid), device serial number (serial), number of recorded measurements (nobs), epoch (epoch), accelerometer mode (mode), start date and time (ts_start), time zone (tz), battery voltage (voltage), download date and time (ts_dl).

error_summary

A list object with file identifier (fileid), summary tables of error codes for each accelerometer data column, error code for date (date), and logical flag for odd number of measurements (odd_number) (see details).

Arguments

file

file name including file extension.

path

path to file.

fileid

label for file identifier.

tz

a character string specifying the timezone to be used for the conversion (see strptime).

sparse

logical flag: should data be stored in sparse format?

fault

numerical value that indicates voltage signal saturation.

Author

Marco Geraci

Details

Raw accelerometer data are processed according to the device data format. See file 'gt3x_sample.dat' in directory '\inst\extdata' of this package.

References

Actigraph (Pensacola, Florida).

Geraci M, Rich C, Sera F, Cortina-Borja M, Griffiths LJ, and Dezateux C (2012). Technical report on accelerometry data processing in the Millennium Cohort Study. London, UK: University College London. Available at https://discovery.ucl.ac.uk/1361699

See Also

readAccDir

Examples

Run this code

data(gt3x_sample)
class(gt3x_sample)

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