SpatialPixelsDataFrame-class {sp} | R Documentation

## Class "SpatialPixelsDataFrame" ~~~

### Description

Class for spatial attributes that have spatial locations on a regular grid.

### Objects from the Class

Objects can be created by calls of the form `as(x, "SpatialPixelsDataFrame")`, where `x` is of class SpatialPointsDataFrame-class, or by importing through rgdal. Ordered full grids are stored instead or unordered non-NA cells;

### Slots

`bbox`:
  Object of class `"matrix"`; bounding box
`proj4string`:
  Object of class `"CRS"`; projection
`grid`:
  see GridTopology-class; grid parameters
`grid.index`:
  integer; index of points in the list to points in the full (ordered) grid. x cycles fastest; all coordinates increase from low to hight except y, which decreases from high to low
`data`:
  Object of class AttributeList-class containing the attribute data

### Extends

Class `"SpatialPixels"`, directly. Class `"Spatial"`, by class `"SpatialPixels"`.

### Methods

coordinates
  `signature(x = "SpatialPixelsDataFrame")`: retrieves (and calculates!) coordinates
[
  `signature(x = "SpatialPixelsDataFrame")`: selects row(s) and/or attribute(s), and returns an object of class `SpatialPixelsDataFrame`; rows refer here to the pixel numbers, not grid lines. For selecting a square block in a grid, coerce to a SpatialGridDataFrame-class first, and use `[` on that object
[[
  `signature(x = "SpatialPixelsDataFrame")`: retrieves an attribute, dropping everything else (topology)
[[<-
  `signature(x = "SpatialPixelsDataFrame")`: assigns or replaces an attribute
as.matrix
  `signature(x = "SpatialPixelsDataFrame")`: coerce to matrix

### Note

### Author(s)

Edzer J. Pebesma, e.pebesma@geo.uu.nl

### References

### See Also

`SpatialPixels-class`, which does not contain the attribute data

### Examples

    data(meuse.grid) # only the non-missing valued cells
    coordinates(meuse.grid) = c("x", "y") # promote to SpatialPointsDataFrame
    gridded(meuse.grid) <- TRUE # promote to SpatialPixelsDataFrame
    meuse.grid[["idist"]] = 1 - meuse.grid[["dist"]] # assigns new attribute
    image(meuse.grid["idist"]) # note the single [

    # toy example:
    df = data.frame(z = c(1:6,NA,8,9),
        xc = c(1,1,1,2,2,2,3,3,3),
        yc = c(rep(c(0, 1.5, 3),3)))
    coordinates(df) = ~xc+yc
    gridded(df) = TRUE
    image(df["z"])
    # draw labels to verify:
    cc = coordinates(df)
    z=df[["z"]]
    zc=as.character(z)
    zc[is.na(zc)]="NA"
    text(cc[,1],cc[,2],zc)

[Package sp version 0.7-12 Index]