Chopping dates and times with santoku

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# Chopping dates with santoku
## David Hugh-Jones

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# Santoku is a package for chopping data.

## It provides `chop()`, a replacement for `base::cut()`.

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# Santoku 0.4.0 can chop dates.

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``` r
y2k <- as.Date("2000-01-01") + 0:365
y2k_sample <- sample(y2k, 60)
brk_dates <- as.Date(c("2000-01-15", "2000-04-01", "2000-08-01"))

chopped <- chop(y2k_sample, brk_dates)
```

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# You can use the usual `chop` functions.

``` r
quartile <- chop_quantiles(y2k_sample, c(0.25, 0.75))
```

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# `lbl_date()` produces nice labels.

``` r
x <- chop(y2k_sample, brk_dates, labels = lbl_date())

table(x)
```

```
## x
##       12-14 Jan 2000 15 Jan - 31 Mar 2000  1 Apr - 31 Jul 2000 
##                    1                   16                   24 
##  1 Aug - 22 Dec 2000 
##                   19
```

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# `chop_width()` works.

* It accepts `difftime`, `lubridate::Period` and `lubridate::Duration` widths.

``` r
  x <- chop_width(y2k, months(1), labels = lbl_endpoints(fmt = "%b"))
         
  table(x)
  ```
  
  ```
  ## x
  ## Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 
  ##  31  29  31  30  31  30  31  31  30  31  30  31
  ```

* `Period` objects get the month right.

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# Chopping time works too.

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background-image: url(figures/crew-dragon.jpg)
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``` r
crew_dragon <- as.POSIXct(c(
                    liftoff = "2020-05-30 15:22", 
                    dock    = "2020-05-31 10:16"), 
                  tz = "America/New_York")

uk_times <- seq(as.POSIXct("2020-05-30 18:00", tz = "GMT"), 
              length.out = 24, by = "hours")

stage <- chop(uk_times, crew_dragon, 
           labels = c("pre-flight", "flight", "docked"))
```

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# `lbl_datetime()` labels datetimes.

``` r
  x <- chop_width(uk_times, hours(4), 
                  labels = lbl_datetime(fmt = "%H:%M %b %d"))
  table(x)
  ```
  
  ```
  ## x
  ##          18:00-22:00 May 30 22:00 May 30 - 02:00 May 31 
  ##                           4                           4 
  ##          02:00-06:00 May 31          06:00-10:00 May 31 
  ##                           4                           4 
  ##          10:00-14:00 May 31          14:00-18:00 May 31 
  ##                           4                           4
  ```
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# Happy chopping!

[CRAN](https://cran.r-project.org/package=santoku)

[github](https://hughjonesd.github.io/santoku)