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https://github.com/eddelbuettel/rcppcctz
Rcpp interface to CCTZ library
https://github.com/eddelbuettel/rcppcctz
c-plus-plus-11 cctz cran datetime datetimes r rcpp timezone timezones
Last synced: 12 days ago
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Rcpp interface to CCTZ library
- Host: GitHub
- URL: https://github.com/eddelbuettel/rcppcctz
- Owner: eddelbuettel
- Created: 2015-10-17T12:34:28.000Z (about 9 years ago)
- Default Branch: master
- Last Pushed: 2024-09-08T19:01:48.000Z (2 months ago)
- Last Synced: 2024-10-12T21:26:15.825Z (26 days ago)
- Topics: c-plus-plus-11, cctz, cran, datetime, datetimes, r, rcpp, timezone, timezones
- Language: C++
- Size: 446 KB
- Stars: 22
- Watchers: 4
- Forks: 8
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: ChangeLog
Awesome Lists containing this project
README
## RcppCCTZ: Rcpp bindings for [CCTZ](https://github.com/google/cctz)
[](https://github.com/eddelbuettel/rcppcctz/actions?query=workflow%3Aci)
[](https://www.gnu.org/licenses/gpl-2.0.html)
[](https://cran.r-project.org/package=RcppCCTZ)
[](https://cran.r-project.org/package=RcppCCTZ)
[](https://www.r-pkg.org/pkg/RcppCCTZ)
[](https://github.com/eddelbuettel/rcppcctz)
### What is CCTZ?
[CCTZ](https://github.com/google/cctz) (C++ Time Zone) is an excellent (yet small) C++11 library for
translating between absolute times and civil times using the rules defined by a time zone. See its
[repository](https://github.com/google/cctz) (as well as code) for very detailed documentation.
[CCTZ](https://github.com/google/cctz) is being developed by Google but not an officially endorsed product.
### What is RcppCCTZ?
This package wraps CCTZ for use by R via [Rcpp](https://dirk.eddelbuettel.com/code/rcpp.html).
### Examples
#### Difference between Timezones
```r
R> # simple call: difference now
R> tzDiff("America/New_York", "Europe/London", Sys.time())
[1] 5
R> # tabulate difference for every week of the year
R> table(sapply(0:52, function(d) tzDiff("America/New_York", "Europe/London",
+ as.POSIXct(as.Date("2016-01-01") + d*7))))
4 5
3 50
```
#### Shifting Timezone
```r
R> # Given current time in NY what is the time London, UK
R> # (running the code locally in Chicago hence CST text format)
R> toTz(Sys.time(), "America/New_York", "Europe/London")
[1] "2016-12-10 17:15:04.20370 CST"
R> # this redoes the 'Armstrong on the moon in NYC and Sydney' example
R> # note that the default print method will print the return object in _your local time_
R> toTz(ISOdatetime(1969,7,20,22,56,0,tz="UTC"), "America/New_York", "Australia/Sydney", TRUE)
1969-07-20 22:56:00 -0400
1969-07-21 12:56:00 +1000
[1] "1969-07-20 21:56:00 CDT"
R> # whereas explicitly formating for Sydney time does the right thing
R> format(toTz(ISOdatetime(1969,7,20,22,56,0,tz="UTC"),
+ "America/New_York", "Australia/Sydney", verbose=TRUE),
+ tz="Australia/Sydney")
1969-07-20 22:56:00 -0400
1969-07-21 12:56:00 +1000
[1] "1969-07-21 12:56:00"
```
#### Parsing and Formatting
```r
R> now <- Sys.time()
R> formatDatetime(now) # current (UTC) time, in full precision RFC3339
[1] "2016-12-10T18:23:03.327956+00:00"
R> formatDatetime(now, tgttzstr="America/New_York") # same but in NY
[1] "2016-12-10T13:23:03.327956-05:00"
R> formatDatetime(now + 0:4) # vectorised
[1] "2016-12-10T18:23:03.327956+00:00" "2016-12-10T18:23:04.327956+00:00"
[3] "2016-12-10T18:23:05.327956+00:00" "2016-12-10T18:23:06.327956+00:00"
[5] "2016-12-10T18:23:07.327956+00:00"
R>
R> ds <- getOption("digits.secs")
R> options(digits.secs=6) # max value
R> parseDatetime("2016-12-07 10:11:12", "%Y-%m-%d %H:%M:%S"); # full seconds
[1] "2016-12-07 04:11:12 CST"
R> parseDatetime("2016-12-07 10:11:12.123456", "%Y-%m-%d %H:%M:%E*S"); # fractional seconds
[1] "2016-12-07 04:11:12.123456 CST"
R> parseDatetime("2016-12-07T10:11:12.123456-00:00") ## default RFC3339 format
[1] "2016-12-07 04:11:12.123456 CST"
R> now <- trunc(Sys.time())
R> parseDatetime(formatDatetime(now + 0:4)) # vectorised
[1] "2016-12-10 12:24:25 CST" "2016-12-10 12:24:26 CST" "2016-12-10 12:24:27 CST"
[4] "2016-12-10 12:24:28 CST" "2016-12-10 12:24:29 CST"
R> options(digits.secs=ds)
```
### Requirements
The [CCTZ](https://github.com/google/cctz) library depends on timezone files typically found in
`/usr/share/zoneinfo` which requires a Unix-alike OS such as Linux or OS X. Old school Unix variants
may work.
### Status
On [CRAN](https://cran.r-project.org/package=RcppCCTZ), builds and tests cleanly,
and the example functions are accessible from R.
### Installation
The package is now on [CRAN](https://cran.r-project.org) and can be installed
via a standard
```r
install.packages("RcppCCTZ")
```
### Continued Testing
As we rely on the [tinytest](https://cran.r-project.org/package=tinytest) package, the
already-installed package can also be verified via
```r
tinytest::test_package("RcppCCTZ")
```
at any later point.
### Author
Dirk Eddelbuettel
### License
GPL (>= 2)