[R-sig-Geo] Antw: transfer raster values to dataframe

[Ross Ahmed]

Great, many thanks Matteo.


On 14/03/2013 22:00, "Matteo Mattiuzzi" <matteo.mattiuzzi at boku.ac.at>
wrote:

>And of coarse the last step was not completely right:
>...
>myPointsDf <- as.data.frame(myPointsSp)
>vals <- extract(myRaster,myPointsSp)
>myPointsDf <- cbind(myPointsDf,vals)
>
>
>
>so now the values are in your data.frame, or maybe also this is ok:
>
>
>myDf <- extract(myRaster,myPointsSp,df=TRUE)
>
>
>
>
>
>>>> Ross Ahmed  14.03.13 22.00 Uhr >>>
>I need to transfer the values from a raster to a dataframe
>programatically.
>Hopefully code below should explain what I need but let me know if not.
>
># make spatial points
>set.seed(1234)
>myPointsSp <- data.frame(x=rnorm(10, mean=1.23347499, sd=0.002),
>y=rnorm(10, mean=52.00096, sd=0.002))
>coordinates(myPointsSp) <- c('x', 'y')
>proj4string(myPointsSp) <- CRS("+proj=longlat +ellps=WGS84 +datum=WGS84")
>
># make raster
>myExtent <- extent((bbox(myPointsSp)))
>myRaster <- raster(ext=myExtent,crs="+proj=longlat +ellps=WGS84
>+datum=WGS84", ncol=2, nrow=2)
>
># assign values to raster
>myRaster[] <- rnorm(4)
>
># cell number of raster that points fall in
>myPointsDf <- as.data.frame(myPointsSp)
>myPointsDf$cell.number <- cellFromXY(myRaster, myPointsSp)
>
># this is what I need - value of cell number transferring to myPointsDf.
>How
>can 
># I do this programatically?
>myPointsDf$cell.value <- c(0.3574899,  0.3054585,  0.7327708, 0.7327708,
>-1.2390943, 0.3054585,
>                           -1.2390943, -1.2390943,  0.3574899, 0.3574899)
>
>
>Thanks
>Ross
>
>
>
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