[GRASS-stats] R image problem with SpatialGridDataFrame

[Ahmadou Dicko]

Hi,

More a R-Sig-Geo question but I'm sure there is connection with the rgrass7
package.
You have some errors because the argument of the image function are not the
right one.
I think you should take a look at the help of the
image.SpatialPixelsDataFrame function (?image.SpatialPixelsDataFrame)

You will see that something along these lines should work

image(year_aegypti, "repro.rate", col = topo.colors(20))
spplot(year_aegypti, "repro.rate")

A final tips when using a Spatial*DataFrame object, it's better to access
directly the column like this 'year_aegypti$repro.rate' instead of
'year_aegypti at data$repro.rate'

Hope it helps



On Wed, Sep 16, 2015 at 2:31 PM, Marisa Donnelly <madonnelly at ucdavis.edu>
wrote:

> Hello,
> I am trying to plot the image of the data from a SpatialGridDataFrame with
> two variables per pixel in R studio. Here is the line I am using and the
> error message I receive after.
>
> > image(year_aegypti at data$repro.rate, col = topo.colors(20))
> Error in image.default(year_aegypti at data$repro.rate, col =
> topo.colors(20)) :
>   argument must be matrix-like
>
> Additionally, here is the structure of the SpatialGridDataFrame I am using
>
>  str(year_aegypti)
> Formal class 'SpatialGridDataFrame' [package "sp"] with 4 slots
>   ..@ data       :'data.frame': 60950 obs. of  2 variables:
>   .. ..$ year_tmean.Aegypti: num [1:60950] NA NA NA NA NA NA NA NA NA NA
> ...
>   .. ..$ repro.rate        : num [1:60950] NA NA NA NA NA NA NA NA NA NA
> ...
>   ..@ grid       :Formal class 'GridTopology' [package "sp"] with 3 slots
>   .. .. ..@ cellcentre.offset: num [1:2] -374000 -606000
>   .. .. ..@ cellsize         : num [1:2] 4000 4000
>   .. .. ..@ cells.dim        : int [1:2] 230 265
>   ..@ bbox       : num [1:2, 1:2] -376000 -608000 544000 452000
>   .. ..- attr(*, "dimnames")=List of 2
>   .. .. ..$ : NULL
>   .. .. ..$ : chr [1:2] "min" "max"
>   ..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slot
>   .. .. ..@ projargs: chr "+proj=aea +lat_1=34 +lat_2=40.5 +lat_0=0
> +lon_0=-120 +x_0=0 +y_0=-4000000 +no_defs +a=6378137 +rf=298.257222101
> +towgs84=0.000,"| __truncated__
>
> I would like to plot only the second variable in the dataframe,
> $year_tmean.Aegypti, but can't quite figure out how. There are NAs in both
> variables, in addition to real numbers.
>
> When I try spplot I get the following error:
>  spplot(year_aegypti at data$repro.rate)
> Error in (function (classes, fdef, mtable)  :
>   unable to find an inherited method for function ‘spplot’ for signature
> ‘"numeric"’
>
> Does anyone have any ideas for solving these issues?
> Thanks!
> Marisa Donnelly
> Ph.D. Student
> Graduate Group in Epidemiology
> University of California, Davis
> madonnelly at ucdavis.edu
>
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-- 
Ahmadou H. DICKO
statistician economist (Ingénieur Statisticien Économiste)
PhD candidate in Climate change economics
Faculty of economics and managment - Cheikh Anta Diop University
West African Science Service Center on Climate Change and Adaptated Land
Use (WASCAL)
Center for Development Research (ZEF) - University of Bonn
email : ahmadou.dicko at ucad.edu.sn
twitter : @dickoah
github : github/dickoa <https://github.com/dickoa>
tel : +221 33 827 55 16
portable: +221 77 123 81 69
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