[R] Calculation of daily max
ggrothendieck at gmail.com
Tue Jan 17 06:32:02 CET 2006
Assuming VDATE is a character vector this produces
a zoo time series object.
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:
gives an introduction to zoo.
Aside from zoo you could check out ?tapply, ?by and ?aggregate .
On 1/16/06, Augusto.Sanabria at ga.gov.au <Augusto.Sanabria at 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 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
> R-help at stat.math.ethz.ch mailing list
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
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