It apparently works now. Something weird happens, though: the new column sums 1 extra hour and assigns the day according to its own time. To solve it I subtracted 1 hour to this new column: niga$night<- as.POSIXct ( ifelse(niga$h>=0 & niga$h<9, niga$a, niga$timepos), origin="1970-01-01") # it works but adds 1 hour (!!!) niga$isnight=niga$night - as.difftime ( 1, units= "hours" ) # subtraction of 1 hour Thank you very much for your time! Santi
From: R. Michael Weylandt <[email protected]> >To: Santiago Guallar <[email protected]> >Cc: "[email protected]" <[email protected]> >Sent: Sunday, May 6, 2012 3:13 PM >Subject: Re: [R] creating a new column assigning values of other columns > >It looks like part of your problem is that some of your time/date >variables are stored as factors rather than actual times / dates. Use >str() to see which ones and try to convert those. You'll need this >format string: format = "%d/%m/%y %H:%M:%S" for the ones that are >currently factors. > >As regards getting POSIXct out of ifelse(), yes -- that seems to be an >infelicity, but I'm sure its easily remedied. You just need: > >as.POSIXct( ifelse( your_code_here) , origin = "1970-01-01") > >Don't add a format string since that refers to the format of the input >(if you're giving a character input), not the output (which is >standardized in the definition of POSIXct) > >Michael > >On Sun, May 6, 2012 at 5:13 AM, Santiago Guallar <[email protected]> wrote: >> Hi Michael, >> Yes, I tried ifelse() before but this function returns a numeric value. When >> I try to convert it back to POSIXct I get a <NA>*. If I use if else I get a >> POSIXct output although it does not return a correct answer (it only returns >> y$timepos even when the condition "h<9" fails to be met). >> Attached the outputs you suggested (thanks, by the way, I didn't know >> dput()). Hope they go through this time. >> >> Thank you, >> >> Santi >> >> *niga$isnight<- as.POSIXct( niga$nit, tz="GMT", format="%Y-%m-%d %H:%M:%S", >> origin="2007-06-19" ) >> >> >> >> From: R. Michael Weylandt <[email protected]> >> To: Santiago Guallar <[email protected]> >> Cc: "[email protected]" <[email protected]> >> Sent: Sunday, May 6, 2012 2:18 AM >> Subject: Re: [R] creating a new column assigning values of other columns >> >> Bahhhh -- far too much work to recreate (and I don't think you sent us >> the file "act.lig"): here's a much better route: >> >> Go to the step immediately before you're in trouble and use dput() on >> your data. R will print out a nice plaintext representation that we >> can copy and paste and reproduce *exactly* without having to do all >> that you show below. >> >> Incidentally, your warning message suggests you should be using >> ifelse() instead of if. >> >> To compare: >> >> x <- seq(-3, 3) >> abs.x.wrong <- if(x < 0) -x else x # Warning message gives some hint >> abs.x.right <- ifelse(x < 0, -x, x) >> >> Hope this helps, >> >> Michael >> >> On Sat, May 5, 2012 at 5:09 PM, Santiago Guallar <[email protected]> wrote: >>> Hello, >>> >>> I have to create a new column from the values of other columns of a data >>> frame. The new column (y$n) is created imposing a condition (using a third >>> variable y$h) that assigns the values of two time variables (y$b and >>> y$timepos). Here's the piece of code to get there (using the attached >>> files): >>> >>> xact <- read.table("act.lig", sep = ',', >>> col.names=c("ok","time","secs","act")) >>> xlig <- read.table("lig.txt", sep = ',', >>> col.names=c("ok","time","secs","lig")) >>> w<- merge(xact, xlig, by = c("time" ,"secs"), all = TRUE, sort=F) >>> require(reshape) >>> z <- cbind(w, colsplit(w$time, split=" ", names=c("date", "clock"))) >>> zh<-cbind(z, colsplit(z$clock, split=":", names=c("h","m","s"))) >>> zhd<- cbind(zh, colsplit(zh$date, split="/", names=c("d","mo","y"))) >>> night <- subset(zhd, zh$lig<6 & zhd$h<9 | zh$lig<6 & zhd$h>21) >>> night$timepos<-as.POSIXct(night$time, tz="GMT", format="%d/%m/%y >>> %H:%M:%S") >>> a=night$timepos - as.difftime( 1, units="days" ) >>> nighta<-cbind(night,a) >>> y<- cbind(nighta, b=as.character(a, tz= "GMT", format= "%Y-%m-%d")) >>> y$n<-with(y, if (h>=0 & h<9) {b} else {timepos}) ## Missing warnings >>> >>> In >>> if (h >= 0 & h < 9) { : >>> >>> condition >>> has length > 1 and only the first element will be used >>> >>> How can I go around this problem and get the new column? >>> >>> Thank you, >>> >>> Santi >>> ______________________________________________ >>> [email protected] 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. >>> >> >> >> >> > > > [[alternative HTML version deleted]]
______________________________________________ [email protected] 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.
