Re: [R] character to time problem

From: Jason Barnhart <jasoncbarnhart_at_msn.com>
Date: Thu, 07 Jun 2007 15:43:48 -0700

Hi John,

  1. The NA appears because '30/02/1995' is not a valid date.

    > strptime('30/02/1995' , "%d/%m/%Y")     [1] NA

b) dates which has the following classes uses sort.POSIXlt which in turns sets na.last to NA. ?order details how NA's are handled in ordering data via na.last.

    > class(dates)
    [1] "POSIXt" "POSIXlt"

    > methods(sort)
    [1] sort.default sort.POSIXlt

    > sort.POSIXlt
    function (x, decreasing = FALSE, na.last = NA, ...)     x[order(as.POSIXct(x), na.last = na.last, decreasing = decreasing)]

    <environment: namespace:base>

After resetting the Feb. date the code works.

HTH,
-jason

>I am trying to clean up some dates and I am clearly
> doing something wrong. I have laid out an example
> that seems to show what is happening with the "real"
> data. The coding is lousy but it looks like it
> should have worked.
>
> Can anyone suggest a) why I am getting that NA
> appearing after the strptime() command and b) why the
> NA is disappearing in the sort()? It happens with
> na.rm=TRUE and na.rm=FALSE
> -------------------------------------------------
> aa <- data.frame( c("12/05/2001", " ", "30/02/1995",
> NA, "14/02/2007", "M" ) )
> names(aa) <- "times"
> aa[is.na(aa)] <- "M"
> aa[aa==" "] <- "M"
> bb <- unlist(subset(aa, aa[,1] !="M"))
> dates <- strptime(bb, "%d/%m/%Y")
> dates
> sort(dates)
> --------------------------------------------------
>
> Session Info
> R version 2.4.1 (2006-12-18)
> i386-pc-mingw32
>
> locale:
> LC_COLLATE=English_Canada.1252;
> LC_CTYPE=English_Canada.1252;
> LC_MONETARY=English_Canada.1252;
> LC_NUMERIC=C;LC_TIME=English_Canada.1252
>
> attached base packages:
> [1] "stats" "graphics" "grDevices" "utils"
> "datasets" "methods" "base"
>
> other attached packages:
> gdata Hmisc
> "2.3.1" "3.3-2"
>
> (Yes I know I'm out of date but I don't like
> upgrading just as I am finishing a project)
>
> Thanks
>
> ______________________________________________
> R-help_at_stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



R-help_at_stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Thu 07 Jun 2007 - 22:53:39 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Fri 08 Jun 2007 - 15:31:54 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.