[R] Aggregate data to lower resolution

Miluji Sb milujisb at gmail.com
Fri Jul 22 23:52:13 CEST 2016


Dear Jean,

Thank you so much for your reply and the solution, This does work. I was
wondering is this similar to 'rasterFromXYZ'? Thanks again!

Sincerely,

Milu

On Fri, Jul 22, 2016 at 3:06 PM, Adams, Jean <jvadams at usgs.gov> wrote:

> Milu,
>
> Perhaps an approach like this would work.  In the example below, I
> calculate the mean GDP for each 1 degree by 1 degree.
>
> temp$long1 <- floor(temp$longitude)
> temp$lat1 <- floor(temp$latitude)
> temp1 <- aggregate(GDP ~ long1 + lat1, temp, mean)
>
>   long1 lat1        GDP
> 1   -69  -55 0.90268640
> 2   -68  -55 0.09831317
> 3   -72  -54 0.22379000
> 4   -71  -54 0.14067290
> 5   -70  -54 0.00300380
> 6   -69  -54 0.00574220
>
> Jean
>
> On Thu, Jul 21, 2016 at 3:57 PM, Miluji Sb <milujisb at gmail.com> wrote:
>
>> Dear all,
>>
>> I have the following GDP data by latitude and longitude at 0.5 degree by
>> 0.5 degree.
>>
>> temp <- dput(head(ptsDF,10))
>> structure(list(longitude = c(-68.25, -67.75, -67.25, -68.25,
>> -67.75, -67.25, -71.25, -70.75, -69.25, -68.75), latitude = c(-54.75,
>> -54.75, -54.75, -54.25, -54.25, -54.25, -53.75, -53.75, -53.75,
>> -53.75), GDP = c(1.683046, 0.3212307, 0.0486207, 0.1223268, 0.0171909,
>> 0.0062104, 0.22379, 0.1406729, 0.0030038, 0.0057422)), .Names =
>> c("longitude",
>> "latitude", "GDP"), row.names = c(4L, 17L, 30L, 43L, 56L, 69L,
>> 82L, 95L, 108L, 121L), class = "data.frame")
>>
>> I would like to aggregate the data 1 degree by 1 degree. I understand that
>> the first step is to convert to raster. I have tried:
>>
>> rasterDF <- rasterFromXYZ(temp)
>> r <- aggregate(rasterDF,fact=2, fun=sum)
>>
>> But this does not seem to work. Could anyone help me out please? Thank you
>> in advance.
>>
>> Sincerely,
>>
>> Milu
>>
>>         [[alternative HTML version deleted]]
>>
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>>
>
>

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