sp: stack – R documentation

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stack

rearrange data in SpatialPointsDataFrame or SpatialGridDataFrame for plotting with spplot (levelplot/xyplot wrapper)

Description

rearrange SpatialPointsDataFrame for plotting with spplot or levelplot

Usage

spmap.to.lev(data, zcol = 1:n, n = 2, names.attr)
## S3 method for class 'SpatialPointsDataFrame'
stack(x, select, ...)
## S3 method for class 'SpatialGridDataFrame'
stack(x, select, ...)

Arguments

`data`	object of class (or extending) SpatialPointsDataFrame or SpatialGridDataFrame
`zcol`	z-coordinate column name(s), or a column number (range) (after removing the spatial coordinate columns: 1 refers to the first non-coordinate column, etc. )
`names.attr`	names of the set of z-columns (these names will appear in the plot); if omitted, column names of `zcol`
`n`	number of columns to be stacked
`x`	same as `data`
`select`	same as `zcol`
`...`	ignored

Value

spmap.to.lev returns a data frame with the following elements:

`x`	x-coordinate for each row
`y`	y-coordinate for each row
`z`	column vector with each of the elements in columns `zcol` of `data` stacked
`name`	factor; name of each of the stacked `z` columns

stack is an S3 method: it return a data.frame with a column values that has the stacked coordinates and attributes, and a column ind that indicates the variable stacked; it also replicates the coordinates.

Examples

library(lattice)
data(meuse.grid) # data frame
coordinates(meuse.grid) = c("x", "y") # promotes to SpatialPointsDataFrame
meuse.grid[["idist"]] = 1 - meuse.grid[["dist"]] # add variable
# the following is made much easier by spplot:
levelplot(z~x+y|name, spmap.to.lev(meuse.grid, z=c("dist","idist"), names.attr =
	c("distance", "inverse of distance")), aspect = "iso")
levelplot(values~x+y|ind, as.data.frame(stack(meuse.grid)),aspect = "iso")
gridded(meuse.grid) = TRUE
levelplot(z~x+y|name, spmap.to.lev(meuse.grid, z=c("dist","idist"), names.attr =
	c("distance", "inverse of distance")), aspect = "iso")
levelplot(values~x+y|ind, as.data.frame(stack(meuse.grid)), asp = "iso")

sp

Classes and Methods for Spatial Data

v1.4-5

GPL (>= 2)

Authors

Edzer Pebesma [aut, cre], Roger Bivand [aut], Barry Rowlingson [ctb], Virgilio Gomez-Rubio [ctb], Robert Hijmans [ctb], Michael Sumner [ctb], Don MacQueen [ctb], Jim Lemon [ctb], Finn Lindgren [ctb], Josh O'Brien [ctb], Joseph O'Rourke [ctb]

Initial release