R portable: not able to install some packages
<p>I have the Rportable 3.3.1 version. Some packages (such as ggplot2) were installed without problem. But some packages that must be compiled from binaries cannot be installed. I have Rtools version 3.4.0.1962 installed on my computer but it seems that it is not detected by Rportable.
The packages that create a problem are:</p>

<ul>
<li>httpuv</li>
<li>jsonlite</li>
<li>sourcetools</li>
</ul>

<p>Which all return the following error:</p>

<pre><code>&gt;install.packages("jsonlite")
Package which is only available in source form, and may need compilation of C/C++/Fortran: ‘jsonlite’
These will not be installed
</code></pre>

<p>How can I tell Rportable where to locate Rtools to compile packages source?</p>