chron is.weekend() function
Hi Paul, This is clearly a bug -- the argument needs to be coerced to a "dates" class argument, since the underlying algorithm relies on integer arithmetic (date+time objects are represented as floating point numbers). Thus you can use is.weekend(dates(mb.df$dtg)) as a workaround. (I'll send you a fix later on).
Paul Hewson wrote:
Hello, I have a dataset which has fields giving both calendar date and weekday. I know better functions are now available, but I am still using chron because of the is.holiday() function and a homemade (even Heath Robinson would be ashamed) is.daylight() function. As a check for typos in the data input, I checked that the dates matched the weekdays. I'm getting some confusing results from the is.weekend function in chron. For example (in US format: mm/dd/yy):
mb.df$dtg[is.weekend(mb.df$dtg) == FALSE & mb.df$Weekday == "Sun"]
[1] (09/24/00 11:52:00) (07/30/00 13:30:00) (04/30/00 15:30:00) [4] (04/30/00 16:28:00) (06/04/00 17:35:00) (09/03/00 14:45:00) [7] (05/07/00 16:42:00) (12/17/00 11:55:00) (08/20/00 10:20:00) [10] (01/07/01 20:32:00) (06/18/00 15:45:00) (09/24/00 11:16:00) [13] (09/10/00 20:35:00) (03/18/00 17:50:00) (09/03/00 09:20:00) [16] (06/18/00 14:37:00) (09/24/00 15:47:00) (09/03/00 20:38:00) I have checked most of these dates on my calendar and it agrees with the original dataset that they are in fact Sundays. Also, I note that is.weekend() seems to think that Fridays from 2000 onwards are weekends. The dataset contains data from 1996 until early 2001 and chron's is.weekend() resolved dates correctly prior to 2000. From the command line however more recent dates are also resolved correctly. For example I tried:
is.weekend("09/02/01")
[1] TRUE and
is.weekend("09/03/01")
[1] FALSE which is correct and therefore gives me some worries about my data, but I would really appreciate any ideas as to where I should start looking. Thanks Paul This was run on R 1.3.0 on Mandrake 7.1 with chron 2.2-17 -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Paul Hewson tel. (01392) 382773 Data Analyst and Research Officer Road Safety Team, Environment Directorate, Devon County Council, 1st Floor, Lucombe House, County Hall Topsham Road Exeter EX2 4QW tel (01392) 382773 fax (01392) 382135 email phewson at devon.gov.uk -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
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