title: Errors installing "dplyr" in r
body: <p>Question: unable to install dplyr in R... code below. Anyone offer any solutions?
  I'm on a mac osx sierra and R Version 1.0.136</p>
  
  <pre><code>&gt; install.packages("dplyr")
  
    There is a binary version available but the source version
    is later:
        binary source needs_compilation
  dplyr  0.5.0  0.7.0              TRUE
  
  Do you want to install from sources the package which needs compilation?
  y/n: 
  y
  installing the source package ‘dplyr’
  
  trying URL 'https://cran.rstudio.com/src/contrib/dplyr_0.7.0.tar.gz'
  Content type 'application/x-gzip' length 690938 bytes (674 KB)
  ==================================================
  downloaded 674 KB
  
  * installing *source* package ‘dplyr’ ...
  ** package ‘dplyr’ successfully unpacked and MD5 sums checked
  ** libs
  xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
  ERROR: compilation failed for package ‘dplyr’
  * removing ‘/Library/Frameworks/R.framework/Versions/3.4/Resources/library/dplyr’
  * restoring previous ‘/Library/Frameworks/R.framework/Versions/3.4/Resources/library/dplyr’
  Warning in install.packages :
    installation of package ‘dplyr’ had non-zero exit status
  
  The downloaded source packages are in
  
  
  ‘/private/var/folders/ll/6vx1dr1n5bb9zwbv1z9v53z00000gn/T/RtmpitMpQn/downloaded_packages’
  &gt; library(dplyr)
  Error: package or namespace load failed for ‘dplyr’ in loadNamespace(i, c(lib.loc, .libPaths()), versionCheck = vI[[i]]):
   there is no package called ‘DBI’
  </code></pre>
  
  <p>Not sure why this isn't working! Tried to download manually and it didn't work either (similar/same warnings/errors)</p>