[R] splitting time vector into days
Greetings -- I have a dataframe a with one element a vector, time, of POSIXct values. What's a good way to split the data frame into periods of a$time, e.g. days, and apply a function, e.g. mean, to some other column of the dataframe, e.g. a$value? Cheers, Alexy __ R-help@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.
Re: [R] splitting time vector into days
?aggregate ?window.zoo ?rollapply anyway have a look at package zoo On Tue, Sep 9, 2008 at 3:25 PM, Alexy Khrabrov [EMAIL PROTECTED] wrote: Greetings -- I have a dataframe a with one element a vector, time, of POSIXct values. What's a good way to split the data frame into periods of a$time, e.g. days, and apply a function, e.g. mean, to some other column of the dataframe, e.g. a$value? Cheers, Alexy __ R-help@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. -- Stephen Sefick Research Scientist Southeastern Natural Sciences Academy Let's not spend our time and resources thinking about things that are so little or so large that all they really do for us is puff us up and make us feel like gods. We are mammals, and have not exhausted the annoying little problems of being mammals. -K. Mullis __ R-help@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.
Re: [R] splitting time vector into days
Here is one way of doing it:
x - data.frame(dates=seq(as.POSIXct('2008-09-08'), by='7 hours', length=10),
+ values=1:10)
# split into days
x.s - split(x, format(x$dates, %Y%m%d))
x.s
$`20080908`
dates values
1 2008-09-08 00:00:00 1
2 2008-09-08 07:00:00 2
3 2008-09-08 14:00:00 3
4 2008-09-08 21:00:00 4
$`20080909`
dates values
5 2008-09-09 04:00:00 5
6 2008-09-09 11:00:00 6
7 2008-09-09 18:00:00 7
$`20080910`
dates values
8 2008-09-10 01:00:00 8
9 2008-09-10 08:00:00 9
10 2008-09-10 15:00:00 10
lapply(x.s, function(.df) mean(.df$values))
$`20080908`
[1] 2.5
$`20080909`
[1] 6
$`20080910`
[1] 9
On Tue, Sep 9, 2008 at 3:25 PM, Alexy Khrabrov [EMAIL PROTECTED] wrote:
Greetings -- I have a dataframe a with one element a vector, time, of
POSIXct values. What's a good way to split the data frame into periods of
a$time, e.g. days, and apply a function, e.g. mean, to some other column of
the dataframe, e.g. a$value?
Cheers,
Alexy
__
R-help@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.
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem that you are trying to solve?
__
R-help@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.
