[R] Calculation of daily max

From: <Augusto.Sanabria_at_ga.gov.au>
Date: Wed 18 Jan 2006 - 13:57:24 EST


Thank you Gabor, the 'aggregate' function operating on zoo(WS) does the job beautifully!

'zoo' has a lot of other goodies too, great package (thanks for that too).

Cheers,

Augusto



Augusto Sanabria. MSc, PhD.
Mathematical Modeller
Risk Research Group
Geospatial & Earth Monitoring Division
Geoscience Australia (www.ga.gov.au)
Cnr. Jerrabomberra Av. & Hindmarsh Dr.
Symonston ACT 2609
Ph. (02) 6249-9155    

-----Original Message-----
From: Gabor Grothendieck [mailto:ggrothendieck@gmail.com] Sent: Tuesday, 17 January 2006 4:32 PM
To: Sanabria Augusto
Cc: r-help@stat.math.ethz.ch
Subject: Re: [R] Calculation of daily max

Assuming VDATE is a character vector this produces a zoo time series object.

	library(zoo)
	z <- aggregate(zoo(WS), as.Date(VDATE), max)

coredata(z) and time(z) are the data vector of maximums and corresponding times, respectively.

The R command:

               vignette("zoo")

gives an introduction to zoo.

Aside from zoo you could check out ?tapply, ?by and ?aggregate .

On 1/16/06, Augusto.Sanabria@ga.gov.au <Augusto.Sanabria@ga.gov.au> wrote:
>
> Good day everyone.
>
> I have a large dataset of 1 min wind speeds
> covering 5 years.
>
> How can I make an array of maximum daily values?
>
> The vectors I have are: 'VDATE' with dates in format '%Y-%m-%d' (like
> '1992-10-28') and 'WS' with wind speed data (same number of elements
> as VDATE).
>
> I want an array with 2 columns: Max daily wind speed and corresponding
> day.
>
> Has anyone got an elegant way of doing that?
> (My background is in C++ I would tend to use loops
> but that is not very elegant in R, isn't it?)
>
> Augusto
>
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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Jan 18 14:06:55 2006

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