Many thanks Mike - that worked straight out-of-the-box :)

One more (potentially silly) query - I have searched around but can't seem to find a suitable  method for what must be a very common problem:

Now I have my image or SpatialGridDataFrame with a ppp pattern plotted over the top of it - how might I go about adding an attribute/column to the each point in the ppp dataset relating to the intensity score of the grid cell it lies within. 

Again, thanks for your assistance with this.
Stepen 



On 31/03/2011, at 1:30 PM, Michael Sumner wrote:

> If image(gridData) works, then image(xbrks, ybrks, gridData) should
> work as well, and plot with the correct spatial coordinates - this
> assumes that xbrks and ybrks correspond to the dimensions of gridData
> - either exactly (the centres) or longer by one element (the corners).
> 
> In the sp package you can do x <-  image2Grid(list(x = xbrks, y =
> ybrks, z = gridData)) to get a SpatialGridDataFrame, and then with
> maptools you can easily convert to spatstat's "im":
> 
> library(maptools)
> x.im <- as.im(x)
> 
> Either of those will help to plot or image() the data in the proper
> space and overplot points.
> 
> Cheers, Mike.
> 
> On Thu, Mar 31, 2011 at 2:21 PM,  <stepen.condors@gmail.com> wrote:
>> Hi all,
>> I have the following datasets and am trying to generate a spatial grid which can be plotted (somewhat like the object created by spatstat's quadratcount):
>> 
>> Dataset 1: A table containing a known number of cells, each value relating to the intensity at a given cell.
>> 
>>> str(gridData)
>> table [1:250, 1:400] 0 0 0 0 0 0 1.72 0 0 0 ...
>> - attr(*, "dimnames")=List of 2
>> ..$ : chr [1:250] "A" "B" "C" "D" ...
>> ..$ : chr [1:400] "A" "B" "C" "D" ...
>> 
>> Datasets 2&3: vectors of xbreaks and ybreaks - specifying the eastings and northings of the grid cells I want to plot.
>> 
>>> str(xbrks)
>> num [1:401] 1740000 1740100 1740200 1740300 1740400 ...
>> 
>>> str(ybrks)
>> num [1:251] 5420000 5420100 5420200 5420300 5420400 ...
>> 
>> 
>> Given these three datatsets, what would be the easiest way to turn this into a plottable (spatially located) grid, that I can then overlay ppp onto?
>> 
>> I am aware that I can simply plot the table as an image, but obviously this is not spatially referenced in anyway so I wouldn't then be able to overlay a point data set and allow the pts and grid polygons to interact.
>> 
>> Any assistance is greatly appreciated.
>> Stepen
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo@r-project.org
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>> 
> 
> 
> 
> -- 
> Michael Sumner
> Institute for Marine and Antarctic Studies, University of Tasmania
> Hobart, Australia
> e-mail: mdsumner@gmail.com
On 31/03/2011, at 1:30 PM, Michael Sumner wrote:

> If image(gridData) works, then image(xbrks, ybrks, gridData) should
> work as well, and plot with the correct spatial coordinates - this
> assumes that xbrks and ybrks correspond to the dimensions of gridData
> - either exactly (the centres) or longer by one element (the corners).
> 
> In the sp package you can do x <-  image2Grid(list(x = xbrks, y =
> ybrks, z = gridData)) to get a SpatialGridDataFrame, and then with
> maptools you can easily convert to spatstat's "im":
> 
> library(maptools)
> x.im <- as.im(x)
> 
> Either of those will help to plot or image() the data in the proper
> space and overplot points.
> 
> Cheers, Mike.
> 
> On Thu, Mar 31, 2011 at 2:21 PM,  <stepen.condors@gmail.com> wrote:
>> Hi all,
>> I have the following datasets and am trying to generate a spatial grid which can be plotted (somewhat like the object created by spatstat's quadratcount):
>> 
>> Dataset 1: A table containing a known number of cells, each value relating to the intensity at a given cell.
>> 
>>> str(gridData)
>>  table [1:250, 1:400] 0 0 0 0 0 0 1.72 0 0 0 ...
>>  - attr(*, "dimnames")=List of 2
>>  ..$ : chr [1:250] "A" "B" "C" "D" ...
>>  ..$ : chr [1:400] "A" "B" "C" "D" ...
>> 
>> Datasets 2&3: vectors of xbreaks and ybreaks - specifying the eastings and northings of the grid cells I want to plot.
>> 
>>> str(xbrks)
>>  num [1:401] 1740000 1740100 1740200 1740300 1740400 ...
>> 
>>> str(ybrks)
>>  num [1:251] 5420000 5420100 5420200 5420300 5420400 ...
>> 
>> 
>> Given these three datatsets, what would be the easiest way to turn this into a plottable (spatially located) grid, that I can then overlay ppp onto?
>> 
>> I am aware that I can simply plot the table as an image, but obviously this is not spatially referenced in anyway so I wouldn't then be able to overlay a point data set and allow the pts and grid polygons to interact.
>> 
>> Any assistance is greatly appreciated.
>> Stepen
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo@r-project.org
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>> 
> 
> 
> 
> -- 
> Michael Sumner
> Institute for Marine and Antarctic Studies, University of Tasmania
> Hobart, Australia
> e-mail: mdsumner@gmail.com


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