Agus,
> any(is.na(SGRGBF40))
returns a RasterLayer with
> min value : 0
> max value : 1
TRUE == 1, so there is at least one NA value
also see:
count(SGRGBF40, NA)
summary(SGRGBF40, maxsamp=ncell(SGRGBF40))
Best, Robert
On Fri, Mar 25, 2011 at 6:58 AM, Agustin Lobo <alobolis...@gmail.com> wrote:
> Hi
>
> I've found that extract() introduces NAs:
> SGRGBF40 =
> brick("/media/Iomega_HDD/UAVetal/CALIBRACIONRADIOM/TESTCASA/CALSEL/SGRGB/SGRGBWBPS125F40.tif")
> calibf2 =
> readOGR(dsn="/media/Iomega_HDD/UAVetal/CALIBRACIONRADIOM/TESTCASA/CALSEL",layer="calibf2",stringsAsFactors=F)
> projection(SGRGBF40) = projection(calibf2)
> plot(subset(SGRGBF40,1))
> plot(calibf2,add=T)
> (overlay is ok now)
>
>> summary(SGRGBF40)
> Cells: 4646400
> NAs : 0 0 0
>
> 1 2 3
> Min. 2629 3 3
> 1st Qu. 34100 22200 18290
> Median 42470 27480 24680
> Mean 40900 28510 25360
> 3rd Qu. 48360 33100 29010
> Max. 65510 65510 64300
> summary based on a sample of 5000 cells, which is 0.107610192837466 %
> of all cells
> To make sure (NAs could outside the sample):
>> any(is.na(SGRGBF40))
> class : RasterLayer
> dimensions : 1760, 2640, 1 (nrow, ncol, nlayers)
> resolution : 1, 1 (x, y)
> extent : 0, 2640, -1759, 1 (xmin, xmax, ymin, ymax)
> projection : +proj=utm +zone=31 +ellps=intl +units=m +no_defs
> values : in memory
> min value : 0
> max value : 1
> So no NAs
> But:
>> summary(v)
> SGRGBWBPS125F40_1 SGRGBWBPS125F40_2 SGRGBWBPS125F40_3
> Min. :18444 Min. : 119.4 Min. : 3
> 1st Qu.:33227 1st Qu.:25516.4 1st Qu.:15633
> Median :37752 Median :36264.1 Median :22374
> Mean :40208 Mean :36275.1 Mean :29737
> 3rd Qu.:46899 3rd Qu.:48052.5 3rd Qu.:48116
> Max. :64992 Max. :63667.1 Max. :63826
> NA's : 5 NA's : 1.0
>
>
> Any explanation to this? Not a big problem (can use na.rm) but I'm
> concerned on this problem implying
> the means not being correct.
>
> Agus
>
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