No problem Wade. My first posts to the list were a hoot.

Any way,  I've shown you how to extract the data using the extent of your
second raster, turning that into a data
frame should be obvious.  You have "cell numbers" so you can also get the
 xy ( xyFromCell)
you can also use cellStats()  and sample() to perform some of the other
tasks you want to.

so just use the help  ?cellStats()   ?sample()   and you should be able to
figure it out.
If not, post your attemps here ( code please, that way we can copy to our
console and run )



On Wed, Jun 6, 2012 at 1:28 PM, Wall, Wade A ERDC-RDE-CERL-IL <
Wade.A.Wall@usace.army.mil> wrote:

> Thank you for your assistance, and apologies for not posting an example.
>
> Wade
>
> -----Original Message-----
> From: steven mosher [mailto:moshersteven@gmail.com]
> Sent: Wednesday, June 06, 2012 3:12 PM
> To: Wall, Wade A ERDC-RDE-CERL-IL
> Cc: r-sig-geo@r-project.org
> Subject: Re: [R-sig-Geo] Working with raster data in R
>
>  The best way to get help is to build a "toy"  working example of the
> problem you face.
>
> 1. Create two rasters, where one is the subset of the other.
> 2. post that code here and what you tried.
> 3 decribe what you want to do in a bit more detail.
>
> You will find that if you post working code and your attemps to solve the
> problem ( as the rules for posting suggest ) that you will get help. So,
>
> First   <- raster(xmn = -180, xmx = 180, ymn = -90, ymx = 90,
>                   ncol = 72, nrow = 36,
>                   crs = "+proj=longlat +datum=WGS84 +ellps=WGS84
> +towgs84=0,0,0")
>
> First[]<-runif(ncell(First))
>
> Second <- crop(First, extent(-70,-50,20,40))
>
> ## put some different values in second
>
> Second[]<-runif(ncell(Second))
>
>
> ##
>
> #now extract the values from the first raster based on the extent of the
> second
>
> Extracted  <- extract(First,extent(Second),cellnumbers=TRUE)
>
>
> That's a start.
>
>
>
>
>
>
> On Wed, Jun 6, 2012 at 10:46 AM, Wall, Wade A ERDC-RDE-CERL-IL <
> Wade.A.Wall@usace.army.mil> wrote:
>
>
>        Hi all,
>
>        I am new to working with raster data, so forgive my ignorance up
> front.
>
>        I have two raster files that I have imported into R using raster().
> The second raster file is a subset of grids within the first raster file
> that covers an area. I would like to create an object (dataframe?) with the
> values from the first raster based on the spatial coordinates of the second
> raster, but cannot figure out how to do this, although it seems to be
> fairly simple.
>
>        Secondly, is there a way to bootstrap values from a raster file.
> For example, I would like to bootstrap X number of grid values and
> calculate the mean value.
>
>        Basically, I want to know if the values in the second raster (the
> subset) are less than the values in the first raster and want to test this
> through bootstrapping the first raster. If there is a better way, please
> let me know.
>
>        Thanks,
>
>        Wade A. Wall
>        US Army ERDC-CERL
>        P.O. Box 9005
>        Champaign, IL  61826-9005
>        1-800-872-2375 ext. 7320 <tel:1-800-872-2375%20ext.%207320>
>        1-217-353-6511 ext. 7320 <tel:1-217-353-6511%20ext.%207320>
>
>        _______________________________________________
>        R-sig-Geo mailing list
>        R-sig-Geo@r-project.org
>        https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
>
>
>

	[[alternative HTML version deleted]]

