[R-sig-Geo] getting mean values for each raster in a stack

[Antonio Silva]

Dear Pebesma

No I din't, thanks. Probably I have not read enough.

extract                 package:raster
fun: function to summarize the values (e.g. ‘mean’). The function
          should take a single numeric vector as argument and return a
          single value (e.g. mean, min or max), and accept a ‘na.rm’
          argument ... ��

Thanks again.

A.O.


2016-05-16 18:01 GMT-03:00 Edzer Pebesma <edzer.pebesma at uni-muenster.de>:

> Did you try:
>
> extract(stack, polygon, mean)
>
> ?
>
> On 16/05/16 22:50, Antonio Silva wrote:
> > Hi,
> >
> > After many trials and some reading I got what I need
> >
> > apply(vals[[1]],2,mean)
> >
> > Anyway I would welcome comments to improve this solution.
> >
> > Best regards
> >
> > Antonio Olinto
> >
> >
> > 2016-05-16 15:32 GMT-03:00 Antonio Silva <aolinto.lst at gmail.com>:
> >
> >> Dear R users
> >>
> >> I have a raster stack and a polygon.
> >>
> >> I want the mean value inside this polygon for each raster in the stack.
> >>
> >> I'm doing the following:
> >>
> >> vals <- extract(stack,polygon)
> >> colMeans(r.vals[[1]]) # only for mean values
> >> # or
> >> for (i in 1:nlayers(stack)) {print(mean(vals[[1]][,i]))} # mean or other
> >> parameter
> >>
> >> I also tried to use lapply, but I got only the overall mean with
> >> lapply(vals, FUN=mean)
> >>
> >> I wonder if there is a way to get the mean (and other parameters) for
> each
> >> layer using lapply function.
> >>
> >> Thanks in advance.
> >>
> >> Antonio Olinto
> >>
> >>
> >
> >
>
> --
> Edzer Pebesma
> Institute for Geoinformatics  (ifgi),  University of Münster
> Heisenbergstraße 2, 48149 Münster, Germany; +49 251 83 33081
> Journal of Statistical Software:   http://www.jstatsoft.org/
> Computers & Geosciences:   http://elsevier.com/locate/cageo/
> Spatial Statistics Society http://www.spatialstatistics.info
>
>
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-- 
Antônio Olinto Ávila da Silva
Biólogo / Oceanógrafo
Instituto de Pesca (Fisheries Institute)
São Paulo, Brasil

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