maptools: readShapeLines – R documentation

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readShapeLines

Read arc shape files into SpatialLinesDataFrame objects

Description

The use of this function is deprecated and it is not being maintained. Use rgdal::readOGR() or sf::st_read() instead - both of these read the coordinate reference system from the input file, while this deprecated function does not. For writing, use rgdal::writeOGR() or sf::st_write() instead.

The readShapeLines function reads data from an arc/line shapefile into a SpatialLinesDataFrame object; the shapefile may be of type polygon, but for just plotting for example coastlines, a SpatialLines object is sufficient. The writeLinesShape function writes data from a SpatialLinesDataFrame object to a shapefile. Note DBF file restrictions in write.dbf.

Usage

readShapeLines(fn, proj4string=CRS(as.character(NA)), verbose=FALSE,
 repair=FALSE, delete_null_obj=FALSE)
writeLinesShape(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 FALSE - 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.
`delete_null_obj`	if TRUE, null geometries will be removed together with their data.frame rows
`x`	a `SpatialLinesDataFrame` 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`

Details

The shpID values of the shapefile will be used as Lines ID values; when writing shapefiles, the object data slot row.names are added to the DBF file as column SL\_ID.

Value

a SpatialLinesDataFrame object

Author(s)

Roger Bivand

Examples

xx <- readShapeLines(system.file("shapes/fylk-val.shp", package="maptools")[1],
 proj4string=CRS("+proj=utm +zone=33 +datum=WGS84"))
plot(xx, col="blue")
summary(xx)
xxx <- xx[xx$LENGTH > 30000,]
plot(xxx, col="red", add=TRUE)
tmpfl <- paste(tempdir(), "xxline", sep="/")
writeLinesShape(xxx, tmpfl)
getinfo.shape(paste(tmpfl, ".shp", sep=""))
axx <- readShapeLines(tmpfl, proj4string=CRS("+proj=utm +zone=33 +datum=WGS84"))
plot(xxx, col="black", lwd=4)
plot(axx, col="yellow", lwd=1, add=TRUE)
unlink(paste(tmpfl, ".*", sep=""))
xx <- readShapeLines(system.file("shapes/sids.shp", package="maptools")[1],
 proj4string=CRS("+proj=longlat +datum=NAD27"))
plot(xx, col="blue")

maptools

Tools for Handling Spatial Objects

v1.1-1

GPL (>= 2)

Authors

Roger Bivand [cre, aut] (<https://orcid.org/0000-0003-2392-6140>), Nicholas Lewin-Koh [aut], Edzer Pebesma [ctb], Eric Archer [ctb], Adrian Baddeley [ctb], Nick Bearman [ctb], Hans-Jörg Bibiko [ctb], Steven Brey [ctb], Jonathan Callahan [ctb], German Carrillo [ctb], Stéphane Dray [ctb], David Forrest [ctb], Michael Friendly [ctb], Patrick Giraudoux [ctb], Duncan Golicher [ctb], Virgilio Gómez Rubio [ctb], Patrick Hausmann [ctb], Karl Ove Hufthammer [ctb], Thomas Jagger [ctb], Kent Johnson [ctb], Matthew Lewis [ctb] (<https://orcid.org/0000-0003-2244-4078>), Sebastian Luque [ctb], Don MacQueen [ctb], Andrew Niccolai [ctb], Edzer Pebesma [ctb], Oscar Perpiñán Lamigueiro [ctb], Ethan Plunkett [ctb], Ege Rubak [ctb] (<https://orcid.org/0000-0002-6675-533X>), Tom Short [ctb], Greg Snow [ctb], Ben Stabler [ctb], Murray Stokely [ctb], Rolf Turner [ctb]

Initial release

2021-03-14