Amazingly enough I think i actually understand that albeit superficially.
Thanks
John Kane
Kingston ON Canada
> -----Original Message-----
> From: smartpink...@yahoo.com
> Sent: Mon, 13 May 2013 11:22:35 -0700 (PDT)
> To: jrkrid...@inbox.com
> Subject: Re: [R] melt in reshape2 destroying dates?
>
> Hi John,
> No problem
>
> If you look at the storage mode:
> storage.mode(mydata$dd1)
> #[1] "integer"
>
> I think during melt, it
> class(mdat$value)
> #[1] "numeric"
> class(mydata$dd1)
> #[1] "POSIXct" "POSIXt"
> I guess during melting, this gets coerced to integer class.
> You can also do:
> mdat$value<-structure(mdat$value,class=c("POSIXt","POSIXct"))
> #or
> as.POSIXct(mdat$value,origin="1970-01-01")
>
> class(mdat$value)
> #[1] "POSIXt" "POSIXct"
> A.K.
>
>
> ----- Original Message -----
> From: John Kane <jrkrid...@inbox.com>
> To: arun <smartpink...@yahoo.com>
> Cc: R help <r-help@r-project.org>
> Sent: Monday, May 13, 2013 2:11 PM
> Subject: Re: [R] melt in reshape2 destroying dates?
>
> Thanks very much. I could have sworn I had tried that but obviously I
> had not.
>
> So melt() is returning the correct value which is what I had suspected
> but I obiously did not convert it properly.I wonder if this buggy enough
> to mention the behaviour to the package maintainer?
>
>
>
> John Kane
> Kingston ON Canada
>
>
>> -----Original Message-----
>> From: smartpink...@yahoo.com
>> Sent: Mon, 13 May 2013 11:05:58 -0700 (PDT)
>> To: jrkrid...@inbox.com
>> Subject: Re: [R] melt in reshape2 destroying dates?
>>
>> In the first case:
>> mdat$value<-.POSIXct(mdat$value,tz="EST")
>> mdat$value[1:3]
>> #[1] "2012-01-01 01:00:00 EST" "2012-01-01 02:00:00 EST"
>> #[3] "2012-01-01 03:00:00 EST"
>> mydata$dd1[1:3]
>> #[1] "2012-01-01 01:00:00 EST" "2012-01-01 02:00:00 EST"
>> #[3] "2012-01-01 03:00:00 EST"
>> A.K.
>>
>>
>>
>> ----- Original Message -----
>> From: John Kane <jrkrid...@inbox.com>
>> To: r-help@r-project.org
>> Cc:
>> Sent: Monday, May 13, 2013 1:36 PM
>> Subject: [R] melt in reshape2 destroying dates?
>>
>> When I melt a data frame with some dates I am getting some strange
>> results. I seem to lose the date format with POSIXct and get a row of
>> zeros with POSIXlt
>>
>> Any suggestions as to what I am messing up? Code and data below.
>> Thanks,
>> John Kane
>> Kingston ON Canada
>>
>> mydata <- structure(list(dd1 = structure(c(1325397600L, 1325401200L,
>> 1325404800L,
>> 1325408400L, 1325412000L, 1325415600L, 1325419200L, 1325422800L,
>> 1325426400L, 1325430000L, 1325433600L, 1325437200L, 1325440800L,
>> 1325444400L, 1325448000L, 1325451600L, 1325455200L, 1325458800L,
>> 1325462400L, 1325466000L), class = c("POSIXct", "POSIXt"), tzone = ""),
>> dd2 = structure(c(1325426400, 1325412000, 1325426400, 1325422800,
>> 1325422800, 1325426400, 1325433600, 1325437200, 1325455200,
>> 1325458800, 1325451600, 1325458800, 1325466000, 1325466000,
>> 1325476800, 1325476800, 1325480400, 1325466000, 1325480400,
>> 1325491200), class = c("POSIXct", "POSIXt"), tzone = ""),
>> emp = structure(c(1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L,
>> 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L), class = "factor", .Label =
>> c("part-time",
>> "self-employed")), period = 1:20), .Names = c("dd1", "dd2",
>> "emp", "period"), row.names = c(NA, -20L), class = "data.frame")
>>
>> library(lubridate)
>> library(reshape2)
>>
>> str(mydata)
>> mdat <- melt(mydata, id=c("emp","period"))
>> str(mdat)
>>
>> # alternatively
>>
>> mydata$dd1 <- as.POSIXlt(mydata$dd1)
>> mydata$dd2 <- as.POSIXlt(mydata$dd2)
>> str(mydata)
>> mdat <- melt(mydata, id=c("emp","period"))
>> str(mdat)
>>
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