R: Date and Time Arithmetic

stri_datetime_add {stringi} | R Documentation

## Date and Time Arithmetic

### Description

Modifies a date-time object by adding a specific amount of time units.

### Usage

    stri_datetime_add(time, value = 1L, units = "seconds", tz = NULL,
      locale = NULL)

    stri_datetime_add(time, units = "seconds", tz = NULL,
      locale = NULL) <- value

### Arguments

`time` | an object of class `POSIXct` or an object coercible to
`value` | integer vector; signed number of units to add to `time`
`units` | single string; one of `"years"`, `"months"`, `"weeks"`, `"days"`, `"hours"`, `"minutes"`, `"seconds"`, or `"milliseconds"`
`tz` | `NULL` or `""` for the default time zone or a single string with a timezone identifier,
`locale` | `NULL` or `""` for default locale, or a single string with locale identifier; a non-Gregorian calendar may be specified by setting the `@calendar=name` keyword

### Details

Vectorized over `time` and `value`.

Note that e.g. January, 31 + 1 month = February, 28 or 29.

### Value

Both functions return an object of class `POSIXct`.

The replacement version of `stri_datetime_add` modifies the state of the `time` object.

### References

Calendar Classes - ICU User Guide, http://userguide.icu-project.org/datetime/calendar

### See Also

Other datetime: `stri_datetime_create`, `stri_datetime_fields`, `stri_datetime_format`, `stri_datetime_fstr`, `stri_datetime_now`, `stri_datetime_symbols`, `stri_timezone_get`, `stri_timezone_info`, `stri_timezone_list`

### Examples

    x <- stri_datetime_now()
    stri_datetime_add(x, units="months") <- 2
    print(x)
    stri_datetime_add(x, -2, units="months")
    stri_datetime_add(stri_datetime_create(2014, 4, 20), 1, units="years")
    stri_datetime_add(stri_datetime_create(2014, 4, 20), 1, units="years", locale="@calendar=hebrew")

    stri_datetime_add(stri_datetime_create(2016, 1, 31), 1, units="months")

[Package stringi version 1.2.4 Index]