time_collapse: Collapse a 'tbl_time' object so that all observations in a...
In DavisVaughan/tibbletime3:

Description Usage Arguments Details Examples

When 'time_collapse' is used, the index of a 'tbl_time' object is altered so that all dates that fall in a period share a common date. This can be useful for further groupwise calculations.

1 2	time_collapse(.data, period = "yearly", start_date = NULL, as_sep_col = FALSE, ...)

`.data`	A 'tbl_time' object.
`period`	A formula or character specification used for time-based grouping. If a formula, e.g. '1~year', the formula is split and parsed to form the grouping period. The 'period' argument accepts a formula of the form 'multiple ~ period' allowing for flexible period grouping. The following are examples: * 1 Year: '1~y' * 3 Months: '3~m' * 90 Days: '90~d' Note that while shorthand is used above, an attempt is made to recognize more explicit period names such as: * 2 Year: '2~year' / '2~years' / '2~yearly' The 'period' argument also accepts characters that are converted to their corresponding periods. The following are accepted: * '"yearly"' or '"y"' * '"quarterly"' or '"q"' * '"monthly"' or '"m"' * '"weekly"' or '"w"' * '"daily"' or '"d"' * '"hour"' or '"h"' * '"minute"' or '"M"' * '"second"' or '"s"'
`start_date`	Optional argument used to specify the start date for the first group. The default is to start at the closest period boundary below the minimum date in the supplied index.
`as_sep_col`	Whether to keep the original index as the column '.date' or to drop it.
`...`	Not currently used.

The date chosen as the common date for a period is always the date at the _end_ of that period.

It is often useful to use 'as_sep_col = TRUE' to keep the original dates as well.

This function respects [dplyr::group_by()] groups.

# Basic functionality -------------------------------------------------------

# Facebook stock prices
data(FB)
FB <- as_tbl_time(FB, date)

# Collapse to weekly dates
time_collapse(FB, period = "weekly")

# Collapse to every other week dates
time_collapse(FB, period = 2~w)

# Collapse to weekly dates, but keep the original too
time_collapse(FB, period = "weekly", as_sep_col = TRUE)

# Grouped functionality -----------------------------------------------------

data(FANG)
FANG <- FANG %>%
  as_tbl_time(date) %>%
  dplyr::group_by(symbol)

# Collapse each group to monthly
FANG %>%
  time_collapse("monthly")

# Collapse each group to every other month
FANG %>%
  time_collapse(2~m)