Use day number on R vistime

Question

Is there any way to show number of day to/from day zero as the x-axis on a vistime plot? i.e. x-axis format as " Day -2, Day -1, Day 0, Day 1, etc "

For example,

library(vistime)
    test = data.frame(event = c('event 1', 'event 2', 'event 3', 'event 4'), 
                        start = c(-5, 2, -4, 0), 
                        end = c(0, 6, -1, 2))
    vistime(test)

This gives the error: Error in value[3L] : is_posixct : df[[col.start]] is not of class 'POSIXct'; it has class 'numeric'.

Answer 1

What about using those vectors as offsets from a "zero-date"?

zerodate <- Sys.Date() # change this to fit your needs.
test = data.frame(event = c('event 1', 'event 2', 'event 3', 'event 4'), 
                        start = zerodate+c(-5, 2, -4, 0), 
                        end = zerodate+c(0, 6, -1, 2))
    vistime(test)