time_id: Time ID

In timeplyr: Fast Tidy Tools for Date and Date-Time Manipulation

Time ID

Description

Generate a time ID that signifies how many time steps away a time value is from the starting time point or more intuitively, this is the time passed since the first time point.

Usage

time_id(x, timespan = granularity(x), g = NULL, na_skip = TRUE, shift = 1L)

Arguments

x	Time vector. E.g. a Date, POSIXt, numeric or any time-based vector.
timespan	timespan.
g	Object used for grouping x. This can for example be a vector or data frame. g is passed directly to collapse::GRP().
na_skip	Should NA values be skipped? Default is TRUE.
shift	Value used to shift the time IDs. Typically this is 1 to ensure the IDs start at 1 but can be 0 or even negative if for example your time values are going backwards in time.

Details

This is heavily inspired by collapse::timeid but differs in 3 ways:

• The time steps need not be the greatest common divisor of successive differences

• The starting time point may not necessarily be the earliest chronologically and thus time_id can generate negative IDs.

• g can be supplied to calculate IDs by group.

time_id(c(3, 2, 1)) is not the same as collapse::timeid(c(3, 2, 1)). In general time_id(sort(x)) should be equal to collapse::timeid(sort(x)). The time difference GCD is always calculated using all the data and not by-group.

Value

An integer vector the same length as x.

See Also

time_elapsed time_seq_id

timeplyr documentation built on April 3, 2025, 6:15 p.m.