title: Errors installing plyr / rcpp
body: <p>I have two computers and in one of them I can't manage to install the plyr package for R.
  This is the error I get:</p>
  
  <pre><code>* installing *source* package ‘plyr’ ...
  ** package ‘plyr’ successfully unpacked and MD5 sums checked
  ** libs
  g++ -I/usr/share/R/include -DNDEBUG   -I"/usr/lib/R/site-library/Rcpp/include"   -fpic  -O2 -pipe -g  -c RcppExports.cpp -o RcppExports.o
  RcppExports.cpp: En la función ‘SEXPREC* plyr_loop_apply(SEXP, SEXP)’:
  RcppExports.cpp:15:9: error: ‘input_parameter’ no es un miembro de ‘Rcpp::traits’
  RcppExports.cpp:15:40: error: expected primary-expression before ‘int’
  RcppExports.cpp:15:40: error: expected ‘;’ before ‘int’
  RcppExports.cpp:16:9: error: ‘input_parameter’ no es un miembro de ‘Rcpp::traits’
  RcppExports.cpp:16:49: error: expected primary-expression before ‘&gt;’ token
  RcppExports.cpp:16:50: error: ‘::type’ no se ha declarado
  RcppExports.cpp:16:57: error: expected ‘;’ before ‘f’
  RcppExports.cpp:17:36: error: ‘n’ no se declaró en este ámbito
  RcppExports.cpp:17:39: error: ‘f’ no se declaró en este ámbito
  RcppExports.cpp: En la función ‘SEXPREC* plyr_split_indices(SEXP, SEXP)’:
  RcppExports.cpp:31:9: error: ‘input_parameter’ no es un miembro de ‘Rcpp::traits’
  RcppExports.cpp:31:54: error: expected primary-expression before ‘&gt;’ token
  RcppExports.cpp:31:55: error: ‘::type’ no se ha declarado
  RcppExports.cpp:31:62: error: expected ‘;’ before ‘group’
  RcppExports.cpp:32:9: error: ‘input_parameter’ no es un miembro de ‘Rcpp::traits’
  RcppExports.cpp:32:40: error: expected primary-expression before ‘int’
  RcppExports.cpp:32:40: error: expected ‘;’ before ‘int’
  RcppExports.cpp:33:65: error: ‘group’ no se declaró en este ámbito
  RcppExports.cpp:33:72: error: ‘n’ no se declaró en este ámbito
  make: *** [RcppExports.o] Error 1
  ERROR: compilation failed for package ‘plyr’
  * removing ‘/home/rgalhama/R/x86_64-pc-linux-gnu-library/2.15/plyr’
  Warning in install.packages :
    installation of package ‘plyr’ had non-zero exit status
  </code></pre>
  
  <p>It looks like the package can't be compiled, but I can't figure out why.
  Before the installation starts, I get this warning message:</p>
  
  <blockquote>
    <p>Warning in install.packages :   dependency ‘Rcpp’ is not available</p>
  </blockquote>
  
  <p>I have installed rcpp from the system (as sudo apt-get install r-cran-rcpp), since I don't find a way to install it from R:</p>
  
  <blockquote>
    <p>install.packages("Rcpp", repos='<a href="http://cran.us.r-project.org" rel="noreferrer">http://cran.us.r-project.org</a>') Installing package(s) into
    ‘/home/rgalhama/R/x86_64-pc-linux-gnu-library/2.15’ (as ‘lib’ is
    unspecified) Warning in install.packages :   package ‘Rcpp’ is not
    available (for R version 2.15.2)</p>
  </blockquote>
  
  <p>But still I don't know if these errors are related.</p>
  
  <p>Any ideas?</p>
  
  <p>Thanks!</p>