raster: creating a layer of NA

Wed, May 25, 2011 11:12 PM

Hi Agus,

That happens because I defined Arith functions for Raster* objects and
numeric values, but not for Raster* objects and logical values. NA is
a logical value, see class(NA). I will add that.

Here are two more work arounds:

r <- D10N2009[[1]] * as.numeric(NA)

r <- calc(D10N2009[[1]], fun=function(x) x * NA)

Robert

On Wed, May 25, 2011 at 3:41 AM, Lyndon Estes <lestes at princeton.edu> wrote:

Based on the example by Pierre:

logo <- raster(system.file("external/rlogo.grd", package="raster"))
# Use this rastre to create a new, void Raster object
r <- raster(logo)

show(r)

class ? ? ? : RasterLayer
dimensions ?: 77, 101, 7777 ?(nrow, ncol, ncell)
resolution ?: 1, 1 ?(x, y)
extent ? ? ?: 0, 101, 0, 77 ?(xmin, xmax, ymin, ymax)
projection ?: +proj=merc +ellps=WGS84
values ? ? ?: none

# Set to NA
r[] <- NA

show(r)

class ? ? ? : RasterLayer
dimensions ?: 77, 101, 7777 ?(nrow, ncol, ncell)
resolution ?: 1, 1 ?(x, y)
extent ? ? ?: 0, 101, 0, 77 ?(xmin, xmax, ymin, ymax)
projection ?: +proj=merc +ellps=WGS84
values ? ? ?: in memory
min value ? : NA
max value ? : NA

So this should work for your raster:

D10N2009[] <- NA


Cheers, Lyndon


On Wed, May 25, 2011 at 2:32 AM, Roman Lu?trik <roman.lustrik at gmail.com> wrote:

I would use setValues on individual layer.

Cheers,
Roman



On Wed, May 25, 2011 at 8:25 AM, Pierre Roudier <pierre.roudier at gmail.com>wrote:

Hi Agustin,

What about this:

# Create a Raster object
logo <- raster(system.file("external/rlogo.grd", package="raster"))
# Use this rastre to create a new, void Raster object
r <- raster(logo)
show(r)

Pierre

2011/5/25 Agustin Lobo <alobolistas at gmail.com>:

HI!

I must create a layer with all missing values. I try:

show(D10N2009)

class ? ? ? : RasterBrick
dimensions ?: 393, 606, 35 ?(nrow, ncol, nlayers)
resolution ?: 0.008928571, 0.008928571 ?(x, y)
extent ? ? ?: -2.004464, 3.40625, 40.49554, 44.00446 ?(xmin, xmax, ymin,

ymax)

projection ?: +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs

+towgs84=0,0,0

values ? ? ?:

/media/Iomega_HDD/FLUXPYR/VGTFLUXPYR1/D10/FLXP_NDD10_2009.vrt

min values ?: 0 0 0 0 0 0 0 0 0 0 ...
max values ?: 255 255 255 255 255 255 255 255 255 255 ...

delme = D10N2009[[1]]*0
show(delme)

class ? ? ? : RasterLayer
dimensions ?: 393, 606, 238158 ?(nrow, ncol, ncell)
resolution ?: 0.008928571, 0.008928571 ?(x, y)
extent ? ? ?: -2.004464, 3.40625, 40.49554, 44.00446 ?(xmin, xmax, ymin,

ymax)

projection ?: +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs

+towgs84=0,0,0

values ? ? ?: in memory
min value ? : 0
max value ? : 0

But

delme = D10N2009[[1]]*NA

Error in D10N2009[[1]] * NA : non-numeric argument to binary operator

I also try

NAvalue(delme) <- 0

but no trace of the NAs:

show(delme)

class ? ? ? : RasterLayer
dimensions ?: 393, 606, 238158 ?(nrow, ncol, ncell)
resolution ?: 0.008928571, 0.008928571 ?(x, y)
extent ? ? ?: -2.004464, 3.40625, 40.49554, 44.00446 ?(xmin, xmax, ymin,

ymax)

projection ?: +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs

+towgs84=0,0,0

values ? ? ?: in memory
min value ? : 0
max value ? : 0

By now I write with NAflag=0 and read back, but there must be a
cleaner way of generating a layer with all NA values
(it's a missing layer for a particular time)

Thanks!

Agus

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raster: creating a layer of NA

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