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Raw-Acceleration Epoch Metrics (ENMO, MAD, z-Angle)

Source: R/raw_metrics.R
raw.metrics.Rd

Reads a raw accelerometer file and returns per-epoch raw activity and posture metrics, the gravity-preserving signals that counts cannot represent: ENMO (Euclidean Norm Minus One, a raw activity metric), MAD (Mean Amplitude Deviation), and the z-angle (arm/posture angle). Auto-calibration (van Hees 2014) is applied first by default. Requires the relevant raw reader (read.gt3x for .gt3x, GGIRread for .cwa/.bin).

Usage

raw.metrics(
  x,
  device = "auto",
  epoch = 60,
  metrics = c("ENMO", "MAD", "anglez"),
  calibrate = TRUE,
  tz = "UTC"
)

Arguments

x

A path to a raw file (.gt3x, .cwa, .bin) or a raw data frame with x/y/z columns in g and an fs attribute (e.g. from example_raw or your own device).

device

One of "auto", "gt3x", "axivity", "geneactiv" (default "auto", inferred from the extension; used only when x is a file path).

epoch

Epoch length in seconds (default 60).

metrics

Which metrics to return; any of "ENMO", "MAD", "anglez" (default all three).

calibrate

Apply van Hees auto-calibration first (default TRUE).

tz

Time zone for the timestamps (default "UTC").

Value

A data frame with time and the requested metrics (ENMO and MAD in mg, anglez in degrees), one row per epoch. The calibration result is attached as the "calibration" attribute.

References

van Hees VT, Gorzelniak L, Dean Leon EC, Eder M, Pias M, Taherian S, Ekelund U, Renstrom F, Franks PW, Horsch A, Brage S (2013). “Separating movement and gravity components in an acceleration signal and implications for the assessment of human daily physical activity.” PLoS ONE, 8(4), e61691. doi:10.1371/journal.pone.0061691 .

Vaha-Ypya H, Vasankari T, Husu P, Suni J, Sievanen H (2015). “A universal, accurate intensity-based classification of different physical activities using raw data of accelerometer.” Clinical Physiology and Functional Imaging, 35(1), 64–70. doi:10.1111/cpf.12127 .

van Hees VT, Sabia S, Anderson KN, Denton SJ, Oliver J, Catt M, Abell JG, Kivimaki M, Trenell MI, Singh-Manoux A (2015). “A novel, open access method to assess sleep duration using a wrist-worn accelerometer.” PLoS ONE, 10(11), e0142533. doi:10.1371/journal.pone.0142533 .

See also

auto.calibrate, circadian.raw, rest.spt, example_raw

Examples

# On a synthetic raw recording (no file needed); pass a path for a real file
# \donttest{
m <- raw.metrics(example_raw(days = 1), epoch = 60)
head(m)
#>                  time     ENMO      MAD    anglez
#> 1 2024-01-01 12:00:00 43.95883 24.78791  8.280445
#> 2 2024-01-01 12:01:00 43.13860 24.89003 14.666095
#> 3 2024-01-01 12:02:00 44.56626 25.55921  8.287697
#> 4 2024-01-01 12:03:00 44.25995 24.90778 14.705513
#> 5 2024-01-01 12:04:00 44.79032 25.36485  8.292428
#> 6 2024-01-01 12:05:00 44.17071 24.72920 14.755796
# }