Create a list of settings for formatting the labels of a
  date axis, to be passed on to the formatter argument of
  amAxisLabels.
amDateAxisFormatter(
  day = c("dd", "MMM dd"),
  week = c("dd", "MMM dd"),
  month = c("MMM", "MMM yyyy")
)vectors of length two, the first component is a formatting string for the dates within a period, and the second one is a formatting string for the dates at a period change; see Formatting date and time
A list of settings for formatting the labels of a date axis.