fasttime: fastPOSIXct – R documentation

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fastPOSIXct

Fast version of as.POSIXct.character for GMT fixed format.

Description

fastPOSIXct converts timestamps in textual (string) form into POSIXct objects. It interprets sequences of digits separated by non-digits as a timestamp in GMT. The order of interpretation is fixed: year, month, day, hour, minute, second. Note that only true (positive) POSIX dates (since 1970-01-01 00:00:00) are supported and fastPOSIXct accepts dates up to year 2199.

It is extremely fast (compared to as.POSIXct by several orders of magnitude (on some platfroms 1000x faster) since it uses pure text parsing and no system calls.

Usage

fastPOSIXct(x, tz = NULL, required.components = 3L)

Arguments

`x`	string vector to interpret as timestamps
`tz`	timezone for the resulting `POSIXct` object - this is NOT the time of `x`, that will always be GMT!
`required.components`	minimum number of timestamp components that are required. For example 3 means only the date is required, 6 means all components (up to the seconds) are required. If the requirement is not met, the result for that entry will be `NA`.

Value

Numeric vector of the class POSIXct. In fact this function computes the numeric vector and calls .POSIXct to create the result.

Author(s)

Simon Urbanek

Examples

## let us generate a bunch of random timestamps until today
  ts <- as.character(.POSIXct(runif(1e4) * unclass(Sys.time()), "GMT"))

  ## convert them using as.POSIXct
  system.time(a <- as.POSIXct(ts, "GMT"))

  ## same using the fast method
  system.time(b <- fastPOSIXct(ts, "GMT"))

  identical(a, b)

fasttime

Fast Utility Function for Time Parsing and Conversion

v1.0-2

GPL-2

Authors

Simon Urbanek <simon.urbanek@r-project.org>

Initial release