Thankyou Achim.
Along these lines, how might I extract subsets from that set by day of week?
eg: create a new series that includes Mondays only.
Thanks,
Alf
----- Original Message -----
From: "Achim Zeileis" <[EMAIL PROTECTED]>
To: "Alfonso Sammassimo" <[EMAIL PROTECTED]>
Cc: <r-help@stat.math.ethz.ch>
Sent: Thursday, March 29, 2007 1:16 AM
Subject: Re: [R] aggregating data with Zoo
> On Wed, 28 Mar 2007, Alfonso Sammassimo wrote:
>
>> Is there a way of aggregating 'zoo' daily data according to day of week?
>> eg
>> all Thursdays
>
> Sure, the easiest way will probably differ depending on the time stamp
> class. One example might be this:
> ## small example with Date index
> z <- read.zoo(file.path(.find.package("zoo"), "doc", "demo1.txt"),
> sep = "|", format = "%d %b %Y")
> ## visualization
> plot(z)
> ## aggregate along week days (via POSIXlt representation)
> aggregate(z, as.POSIXlt(time(z))$wday, mean)
>
> hth,
> Z
>
>> I came across the 'nextfri' function in the documentation but am unsure
>> how
>> to change this so any day of week can be aggregated.
>>
>> I have used POSIX to arrange the data (not as 'zoo' series) according to
>> day
>> of week, but am curious if I've missed if a similar option available with
>> zoo.
>>
>> Thank you for any help,
>>
>> Alf Sammassimo
>> Melbourne, Australia
>>
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>>
>>
>
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