Message-ID: <BANLkTikroj9r+AbSeiWZiQxBiNWsuBf9_A@mail.gmail.com>
Date: 2011-05-25T06:25:02Z
From: Pierre Roudier
Subject: raster: creating a layer of NA
In-Reply-To: <BANLkTinTFFv8dOXYU+ByuJB7MH3-b4chxA@mail.gmail.com>
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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--
Scientist
Landcare Research, New Zealand