## read in date info in format 'ddmmmyyyy' ## This will give NA(s) in some locales; setting the C locale ## as in the commented lines will overcome this on most systems. ## lct <- Sys.getlocale("LC_TIME"); Sys.setlocale("LC_TIME", "C") x <- c("1jan1960", "2jan1960", "31mar1960", "30jul1960") z <- as.Date(x, "%d%b%Y") ## Sys.setlocale("LC_TIME", lct) z ## read in date/time info in format 'm/d/y' dates <- c("02/27/92", "02/27/92", "01/14/92", "02/28/92", "02/01/92") as.Date(dates, "%m/%d/%y") ## date given as number of days since 1900-01-01 (a date in 1989) as.Date(32768, origin = "1900-01-01") ## Excel is said to use 1900-01-01 as day 1 (Windows default) or ## 1904-01-01 as day 0 (Mac default), but this is complicated by Excel ## incorrectly treating 1900 as a leap year. ## So for dates (post-1901) from Windows Excel as.Date(35981, origin = "1899-12-30") # 1998-07-05 ## and Mac Excel as.Date(34519, origin = "1904-01-01") # 1998-07-05 ## (these values come from http://support.microsoft.com/kb/214330) ## Experiment shows that Matlab's origin is 719529 days before ours, ## (it takes the non-existent 0000-01-01 as day 1) ## so Matlab day 734373 can be imported as as.Date(734373, origin = "1970-01-01") - 719529 # 2010-08-23 ## (value from ## http://www.mathworks.de/de/help/matlab/matlab_prog/represent-date-and-times-in-MATLAB.html) ## Time zone effect z <- ISOdate(2010, 04, 13, c(0,12)) # midnight and midday UTC as.Date(z) # in UTC ## these time zone names are common as.Date(z, tz = "NZ") as.Date(z, tz = "HST") # Hawaii
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