This function provides a date summary for Actigraph GT1M accelerometer files.
dateSummary(object, wear, timestamp, minval = 0,
rescale.epoch = 60, keep.error = FALSE)A data frame containing the following variables
file identifier
dates by calendar day
frequency of accelerometer observations in each day
total hours of accelerometer observations in each day
starting time of accelerometer observations
end time of accelerometer observations
wear time (minutes)
dummy variable to define starting date (1 = yes)
dummy variable to define end date (1 = yes)
dummy variable to define truncated date (1 = yes)
an object of class gt1m.
a vector that classifies wear and non-wear time. See markwear.accfile.
a timestamp vector for accelerometer values that can be provided by tsFormat.
threshold defining the minimum number of minutes to identify first and last days. See details.
epoch expressed in the same unit as acceleromenter's epoch to determine minutes of wear time (default is 60 and assumed to be in seconds).
logical flag. If FALSE (default) data errors as identified by errorChk will be replaced by NAs.
Marco Geraci
Based on total wear time (in minutes) for each day, the theshold minval is applied to identify the first and last days. For example, if accelerometers are sent by post to collect survey data, the first and last days in which the accelerometer was worn might not be known. Days before the first and those after the last day (truncated days) are discarded by collapse.accfile.
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
collapse.accfile