[R-SIG-Mac] Mac-only problem using readOGR() to read a shapefile from a directory on a USB pen drive

Mon Mar 6 18:56:30 CET 2017

It would be informative to try ogrInfo from the shell prompt (i.e., outside of R) to find out if this is an R problem or an ogrInfo problem.

-Don

-- 
Don MacQueen

Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062

On 3/4/17, 3:40 AM, "R-SIG-Mac on behalf of D G. Rossiter" <r-sig-mac-bounces at r-project.org on behalf of d.g.rossiter at cornell.edu> wrote:

    Thanks to Ken Beath, this indeed was the problem. I tested by formatting a USB drive to Mac format with Disk Info, copying the shapefiles onto it, and then reading with readOGR().

    Problem solved, although the Mac-formatted USB drive could not be used to transfer files to and from Windows machines.

    D G (David) Rossiter
    Section of Soil & Crop Sciences
    Cornell University
    http://www.css.cornell.edu/faculty/dgr2/

      1. Re:  Mac-only problem using readOGR(), which uses ogrInfo(),
         to read a shapefile from a directory on a USB pen drive (Ken Beath)

    From: Ken Beath <ken at kjbeath.com.au<mailto:ken at kjbeath.com.au>>
    Subject: Re: [R-SIG-Mac] Mac-only problem using readOGR(), which uses ogrInfo(), to read a shapefile from a directory on a USB pen drive
    Date: 3 March 2017 at 20:28:33 GMT-5
    To: "D G. Rossiter" <d.g.rossiter at cornell.edu<mailto:d.g.rossiter at cornell.edu>>
    Cc: "r-sig-mac at r-project.org<mailto:r-sig-mac at r-project.org>" <r-sig-mac at r-project.org<mailto:r-sig-mac at r-project.org>>

    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.rossiter at cornell.edu<mailto:d.g.rossiter at 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/

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