This works perfect, thank you very much Rui!

On Fri, Oct 12, 2012 at 1:35 PM, Rui Barradas <ruipbarradas@sapo.pt> wrote:

> Hello,
>
> Try the following.
>
>
> dat <- read.table(text="
>
>      ID        group Start_date Time_of_experiment Time_of_end
> 1    20209         4    02/02/2009           12:38:00
> 26   30209         3   03/02/2009           12:40:00      13:32:00
> 27   31609         4   03/16/2009           11:28:00      12:26:00
> 28   40609         4   04/06/2009           11:17:00
> 53   42709         4   04/27/2009           11:15:00       9:30:00
> 76   51109         3   05/11/2009           11:51:00
> 101  51809         1  05/18/2009           12:28:00
> 126  62209         3  06/22/2009           11:31:00
> 150  71309         4  07/13/2009           12:12:00      13:37:00
> 173  81009         4  08/10/2009           11:32:00      20:52:00
> ", header=TRUE, fill=TRUE)
> str(dat)
>
> dat$start_time <- with(dat, paste(Start_date, Time_of_experiment))
> dat$Start_of_Experiment <-
>     as.POSIXct(strptime(dat$start_**time, "%m/%d/%Y %H:%M:%S"))
>
> #--- Create End_of_Experiment
> idx <- dat$Time_of_end != ''
> dat$End_of_Experiment <- dat$Start_of_Experiment + 48*60*60
> dat$End_of_Experiment[idx] <-
>     as.POSIXct(strptime(paste(dat$**Start_date, dat$Time_of_end)[idx],
> "%m/%d/%Y %H:%M:%S"))
> dat
>
>
> Hope this helps,
>
> Rui Barradas
> Em 12-10-2012 18:59, Charles Determan Jr escreveu:
>
>> Greetings,
>>
>> My data set has dates and times that I am working with.  Some of the times
>> in Time_of_end are blank.  This is supposed to dictate that the particular
>> experiment lasted 48 hours.  I would like to add 48 hours to the start
>> Start_of_Experiment for another column as End_of_Experiment including both
>> the ones with 48 added and those with early times.  I was thinking
>> something with a conditional statement but I can't seem to figure out what
>> code to use.  Any insight would be appreciated.  Let me know if there is
>> anything else you need.  Thanks for your time.
>>
>> I have Start_of_Experiment in POSIX format for time calculations from the
>> following:
>>
>> data$Start_of_Experiment=as.**POSIXct(strptime(data$start_**time,
>> "%m/%d/%Y
>> %H:%M:%S"))
>>
>> Here is a subset of my data.
>>
>>          ID        group Start_date Time_of_experiment Time_of_end
>> 1    20209         4    02/02/2009           12:38:00
>> 26   30209         3   03/02/2009           12:40:00      13:32:00
>> 27   31609         4   03/16/2009           11:28:00      12:26:00
>> 28   40609         4   04/06/2009           11:17:00
>> 53   42709         4   04/27/2009           11:15:00       9:30:00
>> 76   51109         3   05/11/2009           11:51:00
>> 101  51809         1  05/18/2009           12:28:00
>> 126  62209         3  06/22/2009           11:31:00
>> 150  71309         4  07/13/2009           12:12:00      13:37:00
>> 173  81009         4  08/10/2009           11:32:00      20:52:00
>>      Start_of_Experiment
>> 1   2009-02-02 12:38:00
>> 26  2009-03-02 12:40:00
>> 27  2009-03-16 11:28:00
>> 28  2009-04-06 11:17:00
>> 53  2009-04-27 11:15:00
>> 76  2009-05-11 11:51:00
>> 101 2009-05-18 12:28:00
>> 126 2009-06-22 11:31:00
>> 150 2009-07-13 12:12:00
>> 173 2009-08-10 11:32:00
>>
>>         [[alternative HTML version deleted]]
>>
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>> PLEASE do read the posting guide http://www.R-project.org/**
>> posting-guide.html <http://www.R-project.org/posting-guide.html>
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>

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