readShapePoints {maptools} | R Documentation

## Read points shape files into SpatialPointsDataFrame objects

### Description

The `readShapePoints` reads data from a points shapefile into a `SpatialPointsDataFrame` object. The `writePointsShape` function writes data from a `SpatialPointsDataFrame` object to a shapefile. Both reading and writing can be carried out for 2D and 3D point coordinates. Note DBF file restrictions in `write.dbf`.

### Usage

    readShapePoints(fn, proj4string = CRS(as.character(NA)), verbose = FALSE,
     repair=FALSE)
    writePointsShape(x, fn, factor2char = TRUE, max_nchar=254)

### Arguments

`fn` | shapefile layer name, when writing omitting the extensions *.shp, *.shx and *.dbf, which are added in the function
`proj4string` | Object of class `CRS`; holding a valid proj4 string
`verbose` | default TRUE - report type of shapefile and number of shapes
`repair` | default FALSE: some shapefiles provided by Geolytics Inc. have values of object sizes stored in the *.shx index file that are eight bytes too large, leading the function to try to read past the end of file. If repair=TRUE, an attempt is made to repair the internal values, permitting such files to be read.
`x` | a `SpatialPointsDataFrame` object
`factor2char` | logical, default TRUE, convert factor columns to character
`max_nchar` | default 254, may be set to a higher limit and passed through to the DBF writer, please see Details in `write.dbf`

### Value

a SpatialPointsDataFrame object

### Author(s)

Roger Bivand

### See Also

`write.dbf`

### Examples

    library(maptools)
    xx <- readShapePoints(system.file("shapes/baltim.shp", package="maptools")[1])
    plot(xx)
    summary(xx)
    xxx <- xx[xx$PRICE < 40,]
    tmpfl <- paste(tempdir(), "xxpts", sep="/")
    writePointsShape(xxx, tmpfl)
    getinfo.shape(paste(tmpfl, ".shp", sep=""))
    axx <- readShapePoints(tmpfl)
    plot(axx, col="red", add=TRUE)
    unlink(paste(tmpfl, ".*", sep=""))
    xx <- readShapePoints(system.file("shapes/pointZ.shp", package="maptools")[1])
    dimensions(xx)
    plot(xx)
    summary(xx)

[Package maptools version 0.8-39 Index]