R/getDayGlucoseValues.R

In MRCIEU/GLU: Derives Summary Variables from Continuous Glucose Monitoring (CGM) data

# The MIT License (MIT)
# Copyright (c) 2018 Louise AC Millard, MRC Integrative Epidemiology Unit, University of Bristol
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# gets the appropriate timepoints - either the whole day, daytime or nighttime
# if interp then:
# for whole day: include also the last timepoint that completes the day
# for daytime: include also the first nighttime timepoint after a daytime period
# for nighttime: include also the first daytime timepoint after a nighttime period
#interp: whether to include the (exclusive) last timepoint, that is needed if interpolating, to finish off the day
getDayGlucoseValues <- function(dayObj, night=FALSE, day=FALSE, interp=FALSE) {

        # remove last time point - this time point is only for interpolation functionality, it's value really belongs to the next day
        glucose = dayObj@glucose

        if (night==TRUE) {

                if (interp == TRUE) {
                        # include first day timepoint after night, for interpolation
                        gx = c(NA, glucose$isnight[1:(nrow(glucose)-1)])
                        ix = which(glucose$isnight == TRUE | (glucose$isnight == FALSE & (!is.na(gx) & gx == TRUE)))
                        glucose = glucose[ix,]
                }
                else {

                        glucose = glucose[1:(nrow(glucose)-1),]
                        glucose = glucose[which(glucose$isnight==TRUE),]
                }


        }
        else if (day==TRUE) {

                if (interp == TRUE) {
                        # include first night timepoint after day, for interpolation
                        gx = c(NA, glucose$isnight[1:(length(glucose$isnight)-1)])
                        ix = which(glucose$isnight == FALSE | (glucose$isnight == TRUE & (!is.na(gx) & gx == FALSE)))
                        glucose = glucose[ix,]
                }
                else {
                        glucose = glucose[1:(nrow(glucose)-1),]
                        glucose = glucose[which(glucose$isnight==FALSE),]
                }
        }
        else {
                # getting whole day but only values for this day

                if (interp == FALSE) {
                        glucose = glucose[1:(nrow(glucose)-1),]
                }

        }

        return(glucose)

}