My thought is that it might be that USB drives are usually MSDOS formatted. Usually not a problem but rgdal works with directories. Formatting in a Mac with Disk Utility might be a work-around, with the limitation that the USB will only work in Macs.
I would also try verbose=TRUE which may give more information. In the absence of other ideas contacting the package author can help. Ken > On 4 Mar 2017, at 3:32 am, D G. Rossiter <d.g.rossi...@cornell.edu> wrote: > > I ran across a Mac-only problem using readOGR(), which uses ogrInfo(), to > read a shapefile from a directory on a USB pen drive. I tested the behaviour > on a Windows 10 machine and did not get the problem. > > Trying to read from the USB drive, with relative and full paths: > >> setwd("/Volumes/ISPRS/“) # this is my connected USB drive >> list.files() > [1] "map7100.dbf" "map7100.prj" > [3] "map7100.sbn" "map7100.sbx" > [5] "map7100.shp" "map7100.shp.xml" > [7] "map7100.shx" >> file.exists("map7100.shp") > [1] TRUE >> usa <- readOGR(dsn=".", layer="map7100") > Error in ogrInfo(dsn = dsn, layer = layer, encoding = encoding, use_iconv = > use_iconv, : > Cannot open data source >> usa <- readOGR(dsn="/Volumes/ISPRS", layer="map7100") > Error in ogrInfo(dsn = dsn, layer = layer, encoding = encoding, use_iconv = > use_iconv, : > Cannot open data source > > But, readOGR reads the shapefile correctly if it’s located on the Mac’s > internal drive: > >> setwd("/Users/rossiter/data/edu/dgeostats/ex") >> file.exists("./ds/NEweather/map7100.shp") > [1] TRUE >> usa <- readOGR(dsn="./ds/NEweather", layer="map7100") > OGR data source with driver: ESRI Shapefile > Source: "./ds/NEweather", layer: "map7100" > with 7926 features > It has 19 fields > > All packages are up to date. Here is the sessionInfo(): > > R version 3.3.2 (2016-10-31) > Platform: x86_64-apple-darwin13.4.0 (64-bit) > Running under: OS X El Capitan 10.11.6 > > locale: > [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8 > > attached base packages: > [1] stats graphics grDevices utils datasets methods base > > other attached packages: > [1] ggplot2_2.2.1 sf_0.3-4 maptools_0.9-1 rgdal_1.2-5 > [5] sp_1.2-4 gstat_1.1-4 > > loaded via a namespace (and not attached): > [1] Rcpp_0.12.9 plyr_1.8.4 xts_0.9-7 tools_3.3.2 > [5] digest_0.6.12 evaluate_0.10 tibble_1.2 gtable_0.2.0 > [9] lattice_0.20-34 DBI_0.5-1 yaml_2.1.14 stringr_1.2.0 > [13] knitr_1.15.1 rprojroot_1.2 grid_3.3.2 spacetime_1.2-0 > [17] foreign_0.8-67 rmarkdown_1.3 udunits2_0.13 magrittr_1.5 > [21] backports_1.0.5 scales_0.4.1 intervals_0.15.1 htmltools_0.3.5 > [25] units_0.4-2 rsconnect_0.7 assertthat_0.1 colorspace_1.3-2 > [29] labeling_0.3 stringi_1.1.2 lazyeval_0.2.0 munsell_0.4.3 > [33] FNN_1.1 zoo_1.7-14 > > This is a problem because several of my students have OS/X machines and like > to work from USB-connected external drives. > > D G (David) Rossiter > Section of Soil & Crop Sciences > Cornell University > http://www.css.cornell.edu/faculty/dgr2/ > > _______________________________________________ > R-SIG-Mac mailing list > R-SIG-Mac@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-mac _______________________________________________ R-SIG-Mac mailing list R-SIG-Mac@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-mac