[R] Converting factor data into Date-time format

[PIKAL Petr]

Hi

Everything seems to be OK. Please check your if your objects are as required by.

str(objects) (and post result if you are in doubt :)

from your attempts I presume that datetime was not created properly
Maybe this can do it, without actual data it is hard to tell exactly.

datetime=as.POSIXct(strptime(paste(l10$Date, l10$Time, sep=" "),format="%m/%d/%Y %H:%M:%S"))

BTW, factors can be converted to POSIX class the same way as character vectors are.

Regards
Petr

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of David L Carlson
> Sent: Tuesday, September 30, 2014 10:43 PM
> To: tandi perkins; r-help at r-project.org
> Subject: Re: [R] Converting factor data into Date-time format
>
> First, use stringsAsFactors=FALSE with the read.csv() function. That
> will prevent the conversion to factors. Then try to convert date and
> time to datetime objects.
>
> -------------------------------------
> David L Carlson
> Department of Anthropology
> Texas A&M University
> College Station, TX 77840-4352
>
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of tandi perkins
> Sent: Tuesday, September 30, 2014 12:55 PM
> To: r-help at r-project.org
> Subject: [R] Converting factor data into Date-time format
>
> Hello R help:
>
>
>
> I am
> new to this forum so I apologize in advance for any protocol missteps.
> I have a data set that is comprised of eight birds with GPS; each of
> which transmit everyday at 8:00 am, 4:00 pm, and midnight for 1 year
> (although I have some missing relocation's).  I am trying to format my
> data to be run in adehabitatLT but I am unsuccessful.  I have a "csv"
> file with the following header: "Craneid, Date, Time, Long, Lat,
> Habitat, BurstID".  R creates factor levels in the all of the data
> except Lat, Long. I have attempted the following to correctly format my
> date and time factors (data=l10):
>
>
>
> First
> attempt:
>
> 1.
>  datetime=as.POSIXct(paste(l10$Date, l10$Time), format="%m/%d/%Y
> %H:%M:%S", "America/Chicago")
>
>
>
> 2.
> coord=data.frame((l10$Longitude), (l10$Latitude))
>
>
>
> 3.
> test=as.ltraj(coord, datetime, l10$Craneid, burst=l10$ID, typeII=TRUE)
>
>
>
> Results:Error
> in as.ltraj(coord, datetime, l10$Craneid, burst = l10$ID, typeII =
> TRUE) :
>
>
> non unique dates for a given burst
>
>
>
> I
> researched this error on the list serve and found that I could have
> duplicates so I checked for duplicates in datetime and the return was
> NULL (I also check for duplicates in Excel as I am in the learning
> stages in R).  Next I read a thread posted on the R help in 2012 with a
> similar problem so I attempted what was suggested as follows:
>
>
>
> 1.
>  datetime=as.POSIXct(strptime(as.character(l10$Date, l10$Time),
> format="%m/%d/%Y %H:%M:%S"))
>
>
>
> 2.test=as.ltraj(coord,
> datetime, l10$Craneid, burst=l10$ID, typeII=TRUE)
>
>
>
> Results:
> Same error.
>
>
>
> Finally,
> I have tried:
>
>
>
> 1.
>  datetime=as.POSIXct(as.character(levels(l10$Date)(l10$Time)),
> format="%m/%d/%Y %H:%M:%S")[l10$Date][l10$Time]
>
>
>
> Results:Error
> in as.POSIXct(as.character(levels(l10$Date)(l10$Time)), format =
> "%m/%d/%Y
> %H:%M:%S") :
>
>
> attempt to apply non-function
>
>
>
> Can
> someone please explain what I am doing wrong?  My goal is to obtain
> trajectories for all birds using each bird as a burst as is detailed in
> the adehabitatLT manual and then to create Bias Random Bridges for each
> bird.
>  I did not include my data but I can if that will be helpful.
>
>
>
> Thank
> you in advance for your help,
>
> TLP
>
>
>       [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org 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 r-project.org 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.

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