Since I wrote this before it was pointed out this is a duplicate, I'll add it as an answer anyway. Basically package fasttime
can help you IF you have dates AFTER 1970-01-01 00:00:00
AND they are GMT
AND they are of the format year, month, day, hour, minute, second
. If you can rewrite your dates to this format then fastPOSIXct
will be quick:
# data
date <- c( "2013/5/31 23:30" , "2013/5/31 23:35" , "2013/5/31 23:40" , "2013/5/31 23:45" )
require(fasttime)
# fasttime function
dates.ft <- fastPOSIXct( date , tz = "GMT" )
# base function
dates <- as.POSIXct( date , format= "%Y/%m/%d %H:%M")
# rough comparison
require(microbenchmark)
microbenchmark( fastPOSIXct( date , tz = "GMT" ) , as.POSIXct( date , format= "%Y/%m/%d %H:%M") , times = 100L )
#Unit: microseconds
# expr min lq median uq max neval
# fastPOSIXct(date, tz = "GMT") 19.598 21.699 24.148 25.5485 215.927 100
# as.POSIXct(date, format = "%Y/%m/%d %H:%M") 160.633 163.433 168.332 181.9800 278.220 100
But the question would be, is it quicker to transform your dates to a format fasttime
can accept or just use as.POSIXct
or buy a faster computer?!