raster::extract NAs introduced?
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 <alobolistas at 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