R: Read content of a directory with accelerometer files

readAccDir {pawacc}

R Documentation

Read content of a directory with accelerometer files

Description

This function reads raw files downloaded from accelerometers and stores them in one directory.

Usage

readAccDir(path, model, ext = "dat", counts.pos = 1,
	tz = "Europe/London", sparse = FALSE,
	fault = 32767, save = TRUE, compress = "gzip",
	compression_level = 6,...)

Arguments

`path`	path to accelerometer files.
`model`	accelerometer model, either 'gt1m' or 'gt3x'.
`ext`	file extension without '.' (default is 'dat').
`counts.pos`	position of first measurement of accelerometer counts. See `gt1mAccFile` for details.
`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 (temporarily used for both accelerometer counts and steps).
`save`	either logical or character. If logical, `save = TRUE` stores accelerometer files as `.Rdata` objects in a new directory ('accRfiles') in `path`. If the directory already exists, confirmation for overwriting will be prompted. `save = FALSE` stores accelerometer files in current R session. Alternatively, an existing folder can be specified.
`compress`	logical or character string specifying whether saving to a named file is to use compression if `save = TRUE`. See argument `compress` in `save`.
`compression_level`	integer: the level of compression to be used. See argument `compression_level` in `save`.
`...`	not used.

Details

This is a wrapper function. It reads raw accelerometer files stored in one directory. The argument ext specifies the extension of the files to look for (e.g., 'dat' or 'txt'). Files with different extension and/or sub-directories are ignored. The data format must be consistent with the specification of model.

Value

Either a set of .Rdata files or a list of objects of class accfile. In both cases, each accelerometer data file is stored as an object of type list and labelled using the data file name. See gt1mAccFile or gt3xAccFile for details.

Author(s)

Marco Geraci

References

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