Create a tsibble object
tsibble(..., key = NULL, index, regular = TRUE, .drop = TRUE)A set of name-value pairs. The names of "key" and "index" should be avoided as they are used as the arguments.
Unquoted variable(s) that uniquely determine time indices. NULL for
empty key, and works with tidy selector (e.g. dplyr::starts_with()).
A bare (or unquoted) variable to specify the time index variable.
Regular time interval (TRUE) or irregular (FALSE). The
interval is determined by the greatest common divisor of index column, if TRUE.
If TRUE, empty key groups are dropped.
A tsibble object.
An extensive range of indices are supported by tsibble: native time classes in R
(such as Date, POSIXct, and difftime) and tsibble's new additions
(such as yearweek, yearmonth, and yearquarter). Some commonly-used classes
have built-in support too, including ordered, hms::hms, zoo::yearmon,
zoo::yearqtr, and nanotime.
For a tbl_ts of regular interval, a choice of index representation has to
be made. For example, a monthly data should correspond to time index created
by yearmonth or zoo::yearmon, instead of Date or POSIXct. Because
months in a year ensures the regularity, 12 months every year. However, if
using Date, a month containing days ranges from 28 to 31 days, which results
in irregular time space. This is also applicable to year-week and year-quarter.
Since the tibble that underlies the tsibble only accepts a 1d atomic
vector or a list, the tsibble doesn't accept types of POSIXlt and timeDate.
Tsibble supports arbitrary index classes, as long as they can be ordered from
past to future. To support a custom class, one needs to define index_valid()
for the class and calculate the interval through interval_pull().
Key variable(s) together with the index uniquely identifies each record:
Empty: an implicit variable. NULL resulting in a univariate time series.
A single variable: For example, data(pedestrian) use the bare Sensor as
the key.
Multiple variables: For example, Declare key = c(Region, State, Purpose)
for data(tourism).
Key can be created in conjunction with tidy selectors like starts_with().
The interval function returns the interval associated with the tsibble.
Regular: the value and its time unit including "nanosecond", "microsecond", "millisecond", "second", "minute", "hour", "day", "week", "month", "quarter", "year". An unrecognisable time interval is labelled as "unit".
Irregular: as_tsibble(regular = FALSE) gives the irregular tsibble. It is
marked with !.
Unknown: if there is only one entry for each key variable, the interval
cannot be determined (?).
An interval is obtained based on the corresponding index representation:
integer/numeric/ordered (ordered factor): either "unit" or "year" (Y)
yearquarter/yearqtr: "quarter" (Q)
yearmonth/yearmon: "month" (M)
yearweek: "week" (W)
Date: "day" (D)
difftime: "quarter" (Q), "month" (M), "week" (W), "day" (D),
"hour" (h), "minute" (m), "second" (s)
POSIXct/hms: "hour" (h), "minute" (m), "second" (s), "millisecond" (us), "microsecond" (ms)
nanotime: "nanosecond" (ns)
A tsibble is sorted by its key first and index.
# NOT RUN {
# create a tsibble w/o a key
tsibble(
date = as.Date("2017-01-01") + 0:9,
value = rnorm(10)
)
# create a tsibble with one key
tsibble(
qtr = rep(yearquarter("201001") + 0:9, 3),
group = rep(c("x", "y", "z"), each = 10),
value = rnorm(30),
key = group
)
# }
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