Functions to convert between spatstats raster format im and sps SpatialGridDataFrame as well as one-way conversion from rasters rasterLayer to im. S4-style as() coercion can be used between im and SpatialGridDataFrame objects., = NULL)



object to coerce from

column name of levels(from) to be treated as a factor; if NULL defaults to last column of from. Ignored if from is not a raster with factor values.



signature(from = "SpatialGridDataFrame", to = "im")


signature(from = "im", to = "SpatialGridDataFrame")


A SpatialGridDataFrame object may contain several columns of data such that several values are associated with each grid cell. In contrast an im object can only contain a single variable value for each cell. In the first data column is used. To convert another column to im format simply extract this column first as shown in the example below.


In spatstat all spatial objects are assumed to be planar. This means that spatstat is not designed to work directly with geographic (longitude and latitude) coordinates. If a sp object is declared to have geographic (unprojected) coordinates maptools refuses to convert directly to spatstat format. Rather, these should be projected first using e.g. spTransform. If you know what you are doing, and really want to force coercion, you can overwrite the proj4string of the sp object with NA, proj4string(x) <- CRS(NA), which will fool the system to think that the data is in local planar coordinates. This is probably not a good idea!

See also


Edzer Pebesma, Roger Bivand


run <- FALSE if (require("spatstat.geom", quietly=TRUE)) run <- TRUE if (run) { ## Extract an example SpatialGridDataFrame and plot it data(meuse.grid) # A data.frame gridded(meuse.grid) = ~x+y # Now a SpatialPixelsDataFrame fullgrid(meuse.grid) <- TRUE # Finally a SpatialGridDataFrame mg_dist <- meuse.grid["dist"] # A SpatialGridDataFrame with a single column image(mg_dist, axes=TRUE) }
if (run) { ## Convert to im format and plot it mg_im <- as(mg_dist, "im") plot(mg_im) }
if (run) { ## Convert back to SpatialGridDataFrame and plot it again mg2 <- image(mg2, axes=TRUE) }
run <- run && require(raster, quietly=TRUE)
#> #> Attaching package: ‘raster’
#> The following objects are masked from ‘package:spatstat.geom’: #> #> area, rotate, shift
if (run) { ## Convert SpatialGridDataFrame -> RasterLayer -> im and plot it r <- as(mg2, "RasterLayer") r_im <- plot(r_im) }
if (run) { rr <- raster(nrow=2, ncol=3) values(rr) <- 1:6 rr <- as.factor(rr) rrr <- rr f <- levels(rrr)[[1]] f$name <- c("vector", "of", "values") f$name2 <- letters[1:6] levels(rrr) <- f print(levels(rrr)) }
#> [[1]] #> ID name name2 #> 1 1 vector a #> 2 2 of b #> 3 3 values c #> 4 4 vector d #> 5 5 of e #> 6 6 values f #>
if (run) { iii <- plot(iii) }
if (run) { iv <-, = "name") plot(iv) }
if (run) { }