> Any suggestion?
Yes, to provide a more complete description of the method and the context
in which it should be useful. If you cannot do that, you probably should
not use the method.
Here is aggregation with "some probability function" that, at least for the
example data, has the property you desire (class frequencies are similar).
library(raster)
# create example data
r <- raster()
set.seed(999)
values(r) <- round(runif(ncell(r))*3)
# aggregate with random sampling
a <- aggregate(r, fact=10, fun=function(x, ...) sample(x, 1))
# get frequencies
fr <- freq(r)
fa <- freq(a)
# as percentage
fr[,2] <- round(100 * fr[,2] / sum(fr[,2]))
fa[,2] <- round(100 * fa[,2] / sum(fa[,2]))
# combine
f <- cbind(fr, fa[,2])
colnames(f)[2:3] <- c('original', 'aggregated')
f
Best, Robert
On Thu, Oct 11, 2012 at 3:23 AM, Robert Pazur <[email protected]> wrote:
> Since the description in literature is not very detailed, i can only guess
> that its based on some probability function.
> Any suggestion?
>
> Robert Pazur
>
>
> 2012/10/10 Robert J. Hijmans <[email protected]>
>
>> I am sure there is a way. Can you describe how this is done? Robert
>>
>> On Wed, Oct 10, 2012 at 5:51 AM, Robert Pazur <[email protected]>wrote:
>>
>>> Dear all,
>>>
>>> using land cover fine scale data set with defined categories:
>>> is there a way ( perhaps in raster, or sp library) how to aggregate this
>>> raster by keeping the overall proportion of each land cover
>>> classes constant (as much as possible)?
>>> this aggregation procedure were described as "adjusted" by several
>>> authors
>>> :
>>>
>>> -Verburg, P. H., Denijs, T., Ritsemavaneck, J., Visser, H., & Dejong, K.
>>> (2004). A method to analyse neighbourhood characteristics of land use
>>> patterns. Computers, Environment and Urban Systems, 28(6), 667â690.
>>> doi:10.1016/j.compenvurbsys.2003.07.001 *page 8*
>>>
>>> -Schmit, C., Rounsevell, M., & Lajeunesse, I. (2006). The limitations of
>>> spatial land use data in environmental analysis. Environmental Science &
>>> Policy, 9(2), 174â188. doi:10.1016/j.envsci.2005.11.006 *page 5*
>>>
>>> -Dendoncker, N., Schmit, C., & Rounsevell, M. (2008). Exploring spatial
>>> data uncertainties in landâuse change scenarios. International Journal of
>>> Geographical Information Science, 22(9), 1013â1030.
>>> doi:10.1080/13658810701812836 *page 3*
>>> *
>>>
>>> *
>>> Thanks in advance,
>>> Robert.
>>>
>>>
>>> -------------------------------------------------------
>>> Robert Pazur<
>>> http://www.sav.sk/index.php?lang=sk&charset=&doc=user-org-user&user_no=6225
>>> >
>>>
>>>
>>> Institute of Geography
>>> Slovak Academy Of Sciences
>>>
>>> Mobile : +421 948 001 705
>>> Skype : ruegdeg
>>>
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>>>
>>>
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>>
>
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