import_actigraph_csv function

Import raw multi-channel accelerometer data stored in Actigraph raw csv format

import_actigraph_csv imports the raw multi-channel accelerometer data stored in Actigraph raw csv format. It supports files from the following devices: GT3X, GT3X+, GT3X+BT, GT9X, and GT9X-IMU.

import_actigraph_csv(
  filepath,
  in_voltage = FALSE,
  has_ts = TRUE,
  header = TRUE
)

Arguments

• filepath: string. The filepath of the input data. The first column of the input data should always include timestamps.
• in_voltage: set as TRUE only when the input Actigraph csv file is in analog quantized format and need to be converted into g value
• has_ts: boolean. If TRUE, the input csv file will have a timestamp column.
• header: boolean. If TRUE, the input csv file will have column names in the first row.

Returns

dataframe. The imported multi-channel accelerometer signal, with the first column being the timestamps in POSXlct format, and the rest columns being accelerometer values in $g$ unit.

Details

For old device (GT3X) that stores accelerometer values as digital voltage. The function will convert the values to $g$ unit using the following equation.

Where $v$ is the max voltage corresponding to the max accelerometer value that can be found in the meta section in the csv file; $r$ is the resolution level which is the number of bits used to store the voltage values. $r$ can also be found in the meta section in the csv file.

How is it used in MIMS-unit algorithm?

This function is a File IO function that is used to import data from Actigraph devices during algorithm validation.

Examples

default_ops = options()
  options(digits.secs=3)

  # Use the sample actigraph csv file provided by the package
  filepath = system.file('extdata', 'actigraph_timestamped.csv', package='MIMSunit')

  # Check file format
  readLines(filepath)[1:15]

  # Load the file with timestamp column
  df = import_actigraph_csv(filepath)

  # Check loaded file
  head(df)

  # Check more
  summary(df)

  # Use the sample actigraph csv file without timestamp
  filepath = system.file('extdata', 'actigraph_no_timestamp.csv', package='MIMSunit')

  # Check file format
  readLines(filepath)[1:15]

  # Load the file without timestamp column
  df = import_actigraph_csv(filepath, has_ts = FALSE)

  # Check loaded file
  head(df)

  # Check more
  summary(df)

  # Restore default options
  options(default_ops)

See Also

Other File I/O functions: export_to_actilife(), import_actigraph_count_csv(), import_actigraph_csv_chunked(), import_actigraph_meta(), import_activpal3_csv(), import_enmo_csv(), import_mhealth_csv_chunked(), import_mhealth_csv()