Why is install.package() - building the package from scratch?
<p>I installed RStudio and R recently on a new laptop</p>

<p>I installed RTools after I noticed that my "packages" (it's source code) - was being downloaded in a temp. folder under "Users...\AppData\ etc. and I couldn't find the actual package and use them.</p>

<p>The RTools then builds the package from source - I think</p>

<p>This did not happen with my earlier RStudio and R isntalls. The packages were downloaded "cleanly" - I don't remember it going to through the source code build process</p>

<pre><code>&gt; install.packages("caret")
also installing the dependencies ‘nloptr’, ‘lme4’, ‘pbkrtest’, ‘car’

Packages which are only available in source form, and may need compilation of
  C/C++/Fortran: ‘nloptr’ ‘lme4’ ‘caret’
Do you want to attempt to install these from sources?
</code></pre>

<p>When I say 'y' to this question - it builds it all right.</p>

<p>Versions:
OS: Windows 10
RStudio: 0.99.903
R: 3.3.1</p>

<p>(P.S. I have not been able to install the 'caret' package, the others I could going through this process.)</p>