Convert a vector of observation dates to a ordered sequence of every day in the time series
Arguments
- dates
a vector of dates, possibly including NA values
- period
the gap between observations as a number or, a negative number means the resulting sequence defines a end of time periods, a positive defines the beginning. may be an integer number of days, or a text string like '2 weeks', '-1 month', etc.
- anchor
defines the day of week the periods start or end. either "start", "end", a day of the week, or a date
- fmt
a strptime formatting string for date range labels.