Dichotomy Index (I < O)

The fraction of in-rest activity counts that fall below the median of the out-of-rest (active) counts, a rest/active separation index used in cancer chronobiology (Mormont et al. 2000). A high I<O means rest is quiet relative to the active day, marking a well-separated rhythm.

Usage

dichotomy.index(counts, rest)

Arguments

counts

Numeric activity vector.

rest

A logical vector (TRUE = rest / in-bed), or a character vector of states where "R"/"S"/"sleep" mark rest. Same length as counts.

Value

An object of class actiRhythm_dichotomy: the index IO (percent), the active-period median, and epoch counts. Never errors.

References

Mormont MC, Waterhouse J, Bleuzen P, Giacchetti S, Jami A, Bogdan A, Lellouch J, Misset JL, Touitou Y, Levi F (2000). “Marked 24-h rest/activity rhythms are associated with better quality of life, better response, and longer survival in patients with metastatic colorectal cancer and good performance status.” Clinical Cancer Research, 6(8), 3038–3045.

Examples

ts <- seq(as.POSIXct("2024-01-01", tz = "UTC"), by = 60, length.out = 2 * 1440)
h  <- as.numeric(format(ts, "%H"))
counts <- ifelse(h >= 23 | h < 7, 5, 300)
dichotomy.index(counts, rest = h >= 23 | h < 7)
#> Dichotomy Index (I<O)
#> 
#>   I<O:             100.0%
#>   Active median:   300.0 counts
#>   Rest / active epochs: 960 / 1920
#>