[R] error with as.factor raster

[Prof Brian Ripley]

On 16/12/2013 15:14, Lauria, Valentina wrote:
> Dear List members,
>
> I am trying to map the habitat suitability of Nephrops and one of my predictor is a categorical variable.
>
> However when I utilised the command "as.factor" (before to create my rasters stack) I get the error message "Error in 1:ncol(r) : argument of length 0".
>
> Could anyone help me?

Yes.  This is a bug in package raster.  So please follow the posting 
guide and report to the maintainer, with the 'at a minimum' information 
missing here (a crucial part being the version of raster).

Using 1:ncol() is bad practice (seq_len is designed for that purpose), 
but the raster maintainer misuses it ca 100x.

>
>> r4 <- raster("C:/POSTDOC/NEPHROPS_Habitat_Mapping/NEPHROPS_HabMod_PAPER1/Scotland/IN_eunis_sed.tif")
>> plot(r4)
>> is.factor(r4)
> [1] TRUE
>> as.factor(r4)
> class       : RasterLayer
> dimensions  : 250, 413, 103250  (nrow, ncol, ncell)
> resolution  : 0.01484784, 0.01484784  (x, y)
> extent      : -7.774709, -1.642552, 54.95371, 58.66567  (xmin, xmax, ymin, ymax)
> coord. ref. : +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0
> data source : C:\POSTDOC\NEPHROPS_Habitat_Mapping\NEPHROPS_HabMod_PAPER1\Scotland\IN_eunis_sed.tif
> names       : IN_eunis_sed
> values      : 1, 6  (min, max)
> attributes  :
> Error in 1:ncol(r) : argument of length 0
>> levels(r4)
> [[1]]
>    ID    OBJECTID Value Count sediment
>    0           1               1         2716        R
>     1           2               2         2249       CS
>     2           3               3         2647       MS
>     3           4              4         6819        M
>     4            5             5          889      MXS
>     5            6             6         3647        S
>
>
> Thank you very much in advance.
> Best Regards,
> Valentina
>
>
>
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>
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>


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595