5

I found two basic ways to open shapefiles in R - using rgdal and maptools:

# 1
require(maptools)
shape_maptools <- readShapeLines("file.shp")

# 2
require(rgdal)
shape_rgdal <- readOGR(".", "file")

The data structures seem exactly the same in both cases (class SpatialLinesDataFrame, package sp). However, while rgdal reads the projection properly, maptools does not (you possibly have to assign the CRS manually):

> proj4string(shape_maptools)
[1] NA
> proj4string(shape_rgdal)
[1] "+proj=utm +zone=31 +ellps=intl +units=m +no_defs"

So, why would I ever use maptools to open shape files? I may only make a mistake of assigning the CRS manually!

May I conclude that both ways are equivalent, but using rgdal is always safer way to do open a  shapefile?

Community
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Tomas
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2 Answers2

4

The following comparison of maptools, rgdal and PBSMapping from the National Center for Ecological Analysis and Synthesis might interest you:

"Read and write ESRI Shapefiles with R"

maj
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1

maptools::readShapeLines() get problem with file name containing spacial character eg. German Umlaut.

rgdal can deal with such case

satart
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