accelerometry (version 2.2.5)

accel.intensities: Classification of Physical Activity Intensities

Description

This function computes the number of minutes with counts in user-defined intensity levels, and the number of counts accumulated during time spent in each intensity level. It is intended for use with minute-to-minute accelerometer data.

Usage

accel.intensities(counts, thresh = c(100, 760, 2020, 5999), skipchecks = FALSE)

Arguments

counts

Time series accelerometer counts vector.

thresh

Vector of four cut-points from which five intensity ranges are derived. For example, if thresh = c(100, 760, 2020, 5999), minutes with 0-99 counts are classified as intensity level 1, minutes with 100-759 counts are classified as intensity level 2, ... , and minuts with 5999 or greater counts are classified as intensity level 5. By default the function also returns time in intensities 2-3, 4-5, and 2-5.

skipchecks

If TRUE, function skips error checking code and runs slightly faster.

Value

An integer vector in which the first eight values are minutes in intensity 1, 2, 3, 4, 5, 2-3, 4-5, and 2-5, respectively, and the next eight values are counts accumulated during time spent in intensity 1, 2, 3, 4, 5, 2-3, 4-5, and 2-5. Intensities 1-5 typically correspond to sedentary, light, lifestyle, moderate, and vigorous.

References

Acknowledgment: This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-0940903.

See Also

accel.weartime, accel.process.uni, accel.process.tri

Examples

# NOT RUN {
# Load in sample data frame
data(unidata)

# Get data from ID number 21005
counts.part1 <- unidata[unidata[, "seqn"] == 21005, "paxinten"]

# Create vector of counts during valid wear time only
counts.part1.weartime <- counts.part1[accel.weartime(counts = counts.part1) == 1]

# Calculate physical activity intensity variables
intensity.variables <- accel.intensities(counts = counts.part1.weartime)
# }