Dear All
I have the following code:
datetime <-c("1/1/13 00:00","1/1/13 12:00","1/2/13
00:00","1/2/13 12:00")
datetime <-as.POSIXct(datetime,format='%m/%d/%Y %H:%M')
times
<-matrix(c(difftime(datetime[2],datetime[1],units="hours"),difftime(datetime[3],datetime[2],units="hours"),difftime(datetime[4],datetime[3],units="hours")))
I would like to aks for some directions on how to make the 'times'
object code a bit more "uniform" to accept differenth lenths of
'datetime'... Occasionally I have the 'datetime' object
include up to 15 date and time points, but that code limits the system from
accepting a longer 'datetime' object. This is what that looks like
(basically same as above, but much longer):
datetime <-c("1/1/13 00:00","1/1/13 12:00","1/2/13
00:00","1/2/13 12:00")
datetime <-as.POSIXct(datetime,format='%m/%d/%Y %H:%M')
times
<-matrix(c(difftime(datetime[2],datetime[1],units="hours"),difftime(datetime[3],datetime[2],units="hours"),difftime(datetime[4],datetime[3],units="hours"),difftime(datetime[5],datetime[4],units="hours"),difftime(datetime[6],datetime[5],units="hours"),difftime(datetime[7],datetime[6],units="hours"),difftime(datetime[8],datetime[7],units="hours"),difftime(datetime[9],datetime[8],units="hours"),difftime(datetime[10],datetime[9],units="hours"),difftime(datetime[11],datetime[10],units="hours"),difftime(datetime[12],datetime[11],units="hours"),difftime(datetime[13],datetime[12],units="hours"),difftime(datetime[14],datetime[13],units="hours"),difftime(datetime[15],datetime[14],units="hours"),difftime(datetime[16],datetime[15],units="hours")))
appreciate the help,
Andras
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a) Please read the Posting Guide and post in plain text as it says to do. This
is an adjustment you must make in your email client software, we cannot advise
you how to do it here.
b) Not clear why you want a matrix. A vector is more typical in R; most of the
time using n*1 matrices is an unnecessary Matlab habit.
c) See ?diff
diff(datetime)
or if you definitely need it:
matrix(diff(datetime),ncol=1)
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Andras Farkas <motyocska at yahoo.com> wrote:
>Dear All
>?
>I have the following code:
>?
>datetime <-c("1/1/13 00:00","1/1/13
12:00","1/2/13 00:00","1/2/13
>12:00")
>datetime <-as.POSIXct(datetime,format='%m/%d/%Y %H:%M')
>times
><-matrix(c(difftime(datetime[2],datetime[1],units="hours"),difftime(datetime[3],datetime[2],units="hours"),difftime(datetime[4],datetime[3],units="hours")))
>
>I would like to aks for some directions on how to make the 'times'
>object code a bit more "uniform" to accept differenth lenths of
>'datetime'... Occasionally I have the 'datetime' object
include?up
>to?15 date and time points, but that code limits the system from
>accepting a longer 'datetime' object. This is what that looks like
>(basically same as above, but much longer):
>?
>datetime <-c("1/1/13 00:00","1/1/13
12:00","1/2/13 00:00","1/2/13
>12:00")
>datetime <-as.POSIXct(datetime,format='%m/%d/%Y %H:%M')
>times
><-matrix(c(difftime(datetime[2],datetime[1],units="hours"),difftime(datetime[3],datetime[2],units="hours"),difftime(datetime[4],datetime[3],units="hours"),difftime(datetime[5],datetime[4],units="hours"),difftime(datetime[6],datetime[5],units="hours"),difftime(datetime[7],datetime[6],units="hours"),difftime(datetime[8],datetime[7],units="hours"),difftime(datetime[9],datetime[8],units="hours"),difftime(datetime[10],datetime[9],units="hours"),difftime(datetime[11],datetime[10],units="hours"),difftime(datetime[12],datetime[11],units="hours"),difftime(datetime[13],datetime[12],units="hours"),difftime(datetime[14],datetime[13],units="hours"),difftime(datetime[15],datetime[14],units="hours"),difftime(datetime[16],datetime[15],units="hours")))
>
>appreciate the help,
>?
>Andras
> [[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.
I think you probably want
format='%m/%d/%y %H:%M')
(lower case "y")
diff() as suggested by Jeff Newmiller is good, except that I don't know
how to control the units using diff().
## so a method that allows specifying units other than hours would be, for
example,
datetime <-c("1/1/13 00:00","1/1/13 12:00","1/2/13
00:00","1/2/13 12:00")
datetime <-as.POSIXct(datetime,format='%m/%d/%y %H:%M')deltas <-
difftime(
datetime[-1], datetime[-length(datetime)] , units='min')
-Don
--
Don MacQueen
Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062
On 5/10/13 10:24 AM, "Andras Farkas" <motyocska at yahoo.com>
wrote:
>Dear All
>
>I have the following code:
>
>datetime <-c("1/1/13 00:00","1/1/13
12:00","1/2/13 00:00","1/2/13 12:00")
>datetime <-as.POSIXct(datetime,format='%m/%d/%Y %H:%M')
>times
><-matrix(c(difftime(datetime[2],datetime[1],units="hours"),difftime(dateti
>me[3],datetime[2],units="hours"),difftime(datetime[4],datetime[3],units="h
>ours")))
>
>I would like to aks for some directions on how to make the 'times'
object
>code a bit more "uniform" to accept differenth lenths of
'datetime'...
>Occasionally I have the 'datetime' object include up to 15 date and
time
>points, but that code limits the system from accepting a longer
>'datetime' object. This is what that looks like (basically same as
above,
>but much longer):
>
>datetime <-c("1/1/13 00:00","1/1/13
12:00","1/2/13 00:00","1/2/13 12:00")
>datetime <-as.POSIXct(datetime,format='%m/%d/%Y %H:%M')
>times
><-matrix(c(difftime(datetime[2],datetime[1],units="hours"),difftime(dateti
>me[3],datetime[2],units="hours"),difftime(datetime[4],datetime[3],units="h
>ours"),difftime(datetime[5],datetime[4],units="hours"),difftime(datetime[6
>],datetime[5],units="hours"),difftime(datetime[7],datetime[6],units="hours
>"),difftime(datetime[8],datetime[7],units="hours"),difftime(datetime[9],da
>tetime[8],units="hours"),difftime(datetime[10],datetime[9],units="hours"),
>difftime(datetime[11],datetime[10],units="hours"),difftime(datetime[12],da
>tetime[11],units="hours"),difftime(datetime[13],datetime[12],units="hours"
>),difftime(datetime[14],datetime[13],units="hours"),difftime(datetime[15],
>datetime[14],units="hours"),difftime(datetime[16],datetime[15],units="hour
>s")))
>
>appreciate the help,
>
>Andras
> [[alternative HTML version deleted]]
>