The goal of warp is to provide tooling to group dates by a variety of periods, such as: yearly, monthly, by second, by week of the month, and more.
library(warp)
You can install the release version from CRAN with:
install.package("warp")
You can install the development version from GitHub with:
# install.packages("pak")
pak::pak("DavisVaughan/warp")
One of the core functions in warp is warp_distance()
, which allows you
to provide a date time vector and compute the “distance” from an
origin
. For example, this computes the number of months from the unix
epoch.
x <- as.Date("1970-01-01") + -2:2
x
#> [1] "1969-12-30" "1969-12-31" "1970-01-01" "1970-01-02" "1970-01-03"
warp_distance(x, period = "month")
#> [1] -1 -1 0 0 0
The values that warp_distance()
returns correspond to the distance
from x
to the origin
, in units defined by the period
and the width
defined by every
. The origin
defaults to the unix epoch of
1970-01-01 00:00:00
in the time zone of x
, but you can change that.
In this case the distances are saying that, for example, "1970-01-02"
is in the same month as the origin, and "1969-12-31"
is 1 month group
away.
You can also compute daily distances. Rather than grouping by 1 day,
let’s lump every 2 days together, starting from the default origin
.
# Groups 1970-01-01 and 1970-01-02 together
warp_distance(x, period = "day", every = 2)
#> [1] -1 -1 0 0 1
You will often want to set your own origin
date. Let’s shift it
forward 1 to 1970-01-02
.
origin <- as.Date("1970-01-02")
origin
#> [1] "1970-01-02"
# Groups 1970-01-02 and 1970-01-03 together
warp_distance(x, period = "day", every = 2, origin = origin)
#> [1] -2 -1 -1 0 0
Another interesting period to group by is the "mweek"
, i.e. the week
of the month. Notice that days 1-7 of January 1970 are grouped into the
same bucket. Also note that days 29-31 of December 1969 fell at the end
of their corresponding month. This irregular week of size 3 is treated
as the 5th week of that month, but the offset value of -1
is still the
number of week buckets from the origin
of 1970-01-01
.
y <- as.Date("1969-12-28") + 0:14
tibble::tibble(
y = y,
mweek = warp_distance(y, "mweek")
)
#> # A tibble: 15 × 2
#> y mweek
#> <date> <dbl>
#> 1 1969-12-28 -2
#> 2 1969-12-29 -1
#> 3 1969-12-30 -1
#> 4 1969-12-31 -1
#> 5 1970-01-01 0
#> 6 1970-01-02 0
#> 7 1970-01-03 0
#> 8 1970-01-04 0
#> 9 1970-01-05 0
#> 10 1970-01-06 0
#> 11 1970-01-07 0
#> 12 1970-01-08 1
#> 13 1970-01-09 1
#> 14 1970-01-10 1
#> 15 1970-01-11 1
The algorithm for warp_distance()
was inspired by xts::endpoints()
.
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