CODEWITHSUNDEEP
rshapefilergdal
Mark Miller
Mark Miller

Reputation: 13103

Read shape file with readOGR verses readShapePoly

I have read a shapefile using readShapePoly in the maptools package, but cannot read that same file with readOGR. I am hoping someone may be able to help me read the shapefile with readOGR.

I downloaded the file orcounty.shp from here: http://geography.uoregon.edu/geogr/topics/maps.htm

I also downloaded the associated files: orcounty.shx, orcounty.sbx, orcounty.sbn, and orcounty.dbf and put all five files in the folder: c:/users/mark w miller/gis_in_R/shapefile_example/

The following code reads the shapefile and displays some attributes:

library(maptools)

setwd('c:/users/mark w miller/gis_in_R/shapefile_example/')

# Oregon county census data (polygons)
orcounty.poly <- readShapePoly('orcounty.shp', proj4string=CRS("+proj=longlat"))
orcounty.line <- readShapeLines('orcounty.shp', proj4string=CRS("+proj=longlat"))

# see projection
summary(orcounty.poly)

Object of class SpatialPolygonsDataFrame
Coordinates:
         min        max
x -124.55840 -116.46944
y   41.98779   46.23626
Is projected: FALSE 
proj4string : [+proj=longlat]
Data attributes:

However, when I try to read that same shapefile using the following code I receive an error:

library(rgdal)

# read shapefile
oregon.map <- readOGR(dsn="c:/users/mark w miller/gis_in_R/shapefile_example/", layer="orcounty")

# convert to dataframe
oregon.map_df <- fortify(oregon.map)

The error message says:

Error in ogrInfo(dsn = dsn, layer = layer, encoding = encoding, use_iconv = use_iconv) : 
  Cannot open file

I can read Natural Earth http://www.naturalearthdata.com/ shapefiles using:

library(rgdal)

setwd("c:/users/mark w miller/gis_in_R/")

# read shapefile
wmap <- readOGR(dsn="ne_110m_physical", layer="ne_110m_land")

So, apparently there is a difference between the Natural Earth shapefiles and the Oregon shapefile orcounty.shp.

Thank you for any advice on how to read orcounty.shp with readOGR. My question is similar to the question here: rgdal / readOGR - unable to read shapefile from .zip

Upvotes: 14

Views: 25557

Answers (4)

Robert Hijmans
Robert Hijmans

Reputation: 47081

raster::shapefile wraps around readOGR to take care of paths and tildes; just pass the full file name.

 library(raster)
 x <- shapefile("c:/users/orcounty.shp')

or 

 y <- shapefile("~/users/orcounty.shp")

Upvotes: 0

MikeRSpencer
MikeRSpencer

Reputation: 1316

For anyone ending up here with this error on a Linux box, I found the problem was using a home path shortcut. i.e.

# Works
readOGR(dsn="/home/user/dir", layer="file")

# Doesn't work
readOGR(dsn="~/dir", layer="file")

I have no idea why.

Upvotes: 3

EdJo1924
EdJo1924

Reputation: 21

I used the file ne_110m_land

Try with this:

setwd('D:/JMSR/codes.R/mapas')
unzip("ne_110m_land.zip")
ogrInfo(".", "ne_110m_land")
wmap <- readOGR(".", "ne_110m_land")

Upvotes: 1

Paulo E. Cardoso
Paulo E. Cardoso

Reputation: 5856

Try to remove your last '/' from file path.

readOGR(dsn = 'c:/users/mark w miller/gis_in_R/shapefile_example',
        layer = 'orcounty')

Upvotes: 18

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