Thanks so much, that worked!
----- Original Message -----
From: "Don MacQueen" <macque...@llnl.gov>
To: "Alice Domalik" <9a...@queensu.ca>, r-help@r-project.org
Sent: Friday, August 5, 2016 2:18:16 PM
Subject: Re: [R] adding a date column with dplyr
What's wrong with this?
df$Night <- as.POSIXct( paste(format(df$Date,'%Y-%m-%d'),'21:30'))
or
df$Night <- trunc(df$Date,'day') + 21*60*60 + 30*60
I believe both of those satisfy "the day of tracking for each animal, but
with the time of 21:30". But perhaps you meant the day that tracking
started, when tracking lasted more than one day...
And then just add 24 hours ("one day later") to that one special case
df$Night[df$ID=='M16c'] <- df$Night[df$ID=='M16c'] + 24*60*60
-Don
--
Don MacQueen
Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062
On 8/5/16, 9:51 AM, "R-help on behalf of Alice Domalik"
<r-help-boun...@r-project.org on behalf of 9a...@queensu.ca> wrote:
>Hi all,
>
>
>I'm having some difficulties adding a conditional element to my code.
>
>I have a time series data set that contains GPS tracking coordinates for
>a population of animals.
>
>
>ID Date Latitude
> Longitude
>15K12 2014-05-22 04:33:00 50.67675 -129.6553
>
>15K12 2014-05-22 04:35:00 50.45613 -129.4566
>15K19 2014-05-24 06:44:00 50.34611 -129.5678 (and
>so on)
>
>I added a new column to this dataset, called "Night", which is the day of
>tracking for each animal, but with the time of 21:30.
>
>
>ID Date Latitude
> Longitude Night
>15K12 2014-05-22 04:33:00 50.67675 -129.6553
>2014-05-22 21:30:00
>
>15K12 2014-05-22 04:35:00 50.45613 -129.4566
>2014-05-22 21:30:00
>15K19 2014-05-24 06:44:00 50.34611 -129.5678
>2015-05-24 21:30:00
>
>I used the following code to do this:
>library(dplyr)
>library(lubridate)
>Sys.setenv(TZ="Canada/Pacific")
>df<-df%>%
> group_by(ID) %>%
> mutate(Night=as.POSIXct(date(min(Date)) + days(0) + hours(21) +
>minutes(30), tz="Canada/Pacific"))
>
>However, I need to add a conditional element, because for one animal,
>"Night" needs to be 1 day later. I tried this code...
>
>df<-df%>%
> group_by(ID) %>%
> mutate(Night=ifelse(test=(id=='M16c'),yes=as.POSIXct(date(min(Date)) +
>days(1) + hours(21) + minutes(30), tz="Canada/Pacific"),
>no=as.POSIXct(date(min(Date)) + days(0) + hours(21) + minutes(30),
>tz="Canada/Pacific")))
>
>The code runs, but instead of having a date, I get a string of numbers
>like "1403497200" in the column "Night".
>Any ideas what the problem could be?
>
>Thanks, Alice
>
>
>
>
> [[alternative HTML version deleted]]
>
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______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
