[R-sig-Geo] Beginners question: From text-raster to grid / map

[Robert J. Hijmans]

Pep,

if you have a matrix m, e.g.,

m <- matrix(1:100, ncol=10, byrow=T)

you can do

library(raster)
r <- raster(m)
xmn <- 2
ymn <- 8
res <- 2
extent(r) <- c(xmn, xmn+ncol(r)*res, ymn, ymn+nrow(r)*res)
plot(r)
xyv <- rasterToPoints(r)


Robert

On Fri, Sep 17, 2010 at 1:49 PM, Crowe, Andrew <a.crowe at lancaster.ac.uk> wrote:
> You could add a header to the ascii file to give it the ESRI format which can then be read into R using the readAsciiGrid function from the maptools package and viewed with the image function
>
> The file should look something like this:
> ncols         4
> nrows         3
> xllcorner     2.0
> yllcorner     8.0
> cellsize      2.0
> NODATA_value  -9999
> 3 6 7 4
> 2 3 4 5
> 4 5 5 6
>
> R commands:
> library(maptools)
> ingrid <- readAsciiGrid("full_file_path")
> image(ingrid)
>
> HTH
>
> Andrew
>
> Dr Andrew Crowe
>
> Lancaster Environment Centre
> Lancaster University
> Lancaster    LA1 4YQ
> UK
>
>
> ________________________________
>
> From: r-sig-geo-bounces at stat.math.ethz.ch on behalf of PEP Serra Diaz
> Sent: Fri 17/09/2010 12:24 PM
> To: r-sig-geo at stat.math.ethz.ch
> Subject: Re: [R-sig-Geo] Beginners question: From text-raster to grid / map
>
>
>
> Sorry, the inteded data.frame is to be like this:
>
> X  Y  VALUE
> 2  8  4
> 4  8  5
> 6  8  5
> 8  8  6
> 2 10 2
> 4 10 3
> 6 10 4
> 8 10 5
> 2 12 3
> 4 12 6
> 6 12 7
> 8 12 4
>
>
>
> ----- Missatge original -----
> De: PEP Serra Diaz <Josep.Serra at uab.cat>
> Data: Divendres, Setembre 17, 2010 1:16 pm
> Assumpte: Beginners question: From text-raster to grid / map
>
>>
>> Dear R-SIGers,
>>
>> I would like to know which function to use in order to plot a map.
>>
>> I know my origin of coordinates (x=2,y=8), and my resolution (2)
>>
>> And I have an ASCII/txt file as an output matrix
>>
>> 3 6 7 4
>> 2 3 4 5
>> 4 5 5 6
>>
>> I would like to plot a map for these values and/or alternatively
>> get a table like that (in other words, assign coordinates to each
>> value of the text.file (matrix))
>>
>
>>
>> Thanks,
>>
>> Pep
>>
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo at stat.math.ethz.ch
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo at stat.math.ethz.ch
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>