The install.packages command looks through the .libPaths variable. Here&#39;s what mine defaults to on OSX:

    &gt; .libPaths()
    [1] &quot;/Library/Frameworks/R.framework/Resources/library&quot;

I don&#39;t install packages there by default, I prefer to have them installed in my home directory. In my .Rprofile, I have this line:

    .libPaths( &quot;/Users/tex/lib/R&quot; )

This adds the directory &quot;/Users/tex/lib/R&quot; to the front of the .libPaths variable. 

This is documented in the &#39;R Installation and Administration&#39; manual that came with your installation.

On my Linux box:

    R&gt; .libPaths()
    [1] &quot;/usr/local/lib/R/site-library&quot; &quot;/usr/lib/R/site-library&quot;      
    [3] &quot;/usr/lib/R/library&quot;           
    R&gt; 

meaning that the default path is the first of these. You can override that via an argument to both `install.packages()` (from inside R) or `R CMD INSTALL` (outside R).

You can also override by setting the R_LIBS_USER variable. 

Thanks for the direction from the above two answerers. James Thompson&#39;s suggestion worked best for Windows users.

1. Go to where your R program is installed. This is referred to as `R_Home` in the literature. Once you find it, go to the /etc subdirectory.

        C:\R\R-2.10.1\etc

2. Select the file in this folder named Rprofile.site. I open it with VIM. You will find this is a bare-bones file with less than 20 lines of code. I inserted the following inside the code:

        # my custom library path
        .libPaths(&quot;C:/R/library&quot;)
 
 (The comment added to keep track of what I did to the file.)

3. In R, typing the `.libPaths()` function yields the first target at `C:/R/Library`

NOTE: there is likely more than one way to achieve this, but other methods I tried didn&#39;t work for some reason.


You do not want the &#39;=&#39;

Use `.libPaths(&quot;C:/R/library&quot;)` in you `Rprofile`.site file

And make sure you have correct &quot; symbol (Shift-2)

Where can I find a detailed manual about PostgreSQL naming conventions? (table names vs. camel case, sequences, primary keys, constraints, indexes, etc...)


PostgreSQL naming conventions

# Background #

I&#39;m a first year CS student and I work part time for my dad&#39;s small business. I don&#39;t have any experience in real world application development. I have written scripts in Python, some coursework in C, but nothing like this.

My dad has a small training business and currently all classes are scheduled, recorded and followed up via an external web application. There is an export/&quot;reports&quot; feature but it is very generic and we need specific reports. We don&#39;t have access to the actual database to run the queries. I&#39;ve been asked to set up a custom reporting system. 

My idea is to create the generic CSV exports and import (probably with Python) them into a MySQL database hosted in the office every night, from where I can run the specific queries that are needed. I don&#39;t have experience in databases but understand the very basics. I&#39;ve read a little about database creation and normal forms.

We may start having international clients soon, so I want the database to not explode if/when that happens. We also currently have a couple big corporations as clients, with different divisions (e.g. ACME parent company, ACME healthcare division, ACME bodycare division)

The schema I have come up with is the following:

1. **From the client perspective:**
    * Clients is the main table
    * Clients are linked to the department they work for
        * Departments can be scattered around a country: HR in London, Marketing in Swansea, etc.
        * Departments are linked to the division of a company
    * Divisions are linked to the parent company  
2. **From the classes perspective:**
    * Sessions is the main table
        * A teacher is linked to each session
        * A statusid is given to each session. E.g. 0 - Completed, 1 - Cancelled
        * Sessions are grouped into &quot;packs&quot; of an arbitrary size
    * Each packs is assigned to a client

I &quot;designed&quot; (more like scribbled) the schema on a piece of paper, trying to keep it normalised to the 3rd form. I then plugged it into MySQL Workbench and it made it all pretty for me:&lt;br&gt; ([Click here for full-sized graphic][1])

[![alt text][2]][2]  
&lt;sub&gt;(source: [maian.org](http://maian.org/img/schema.png))&lt;/sub&gt;  


## Example queries I&#39;ll be running ##

* Which clients with credit still left are inactive (those without a class scheduled in the future)
* What is the attendance rate per client/department/division (measured by the status id in each session)
* How many classes has a teacher had in a month
* Flag clients who have low attendance rate
* Custom reports for HR departments with attendance rates of people in their division

# Question(s) #

* **Is this overengineered or am I headed the right way?**
* Will the need to join multiple tables for most queries result in a big performance hit?
* I have added a &#39;lastsession&#39; column to clients, as it is probably going to be a common query. Is this a good idea or should I keep the database strictly normalised?

Thanks for your time


  [1]: http://maian.org/img/schema.png
  [2]: https://i.stack.imgur.com/JU8cW.png

First-time database design: am I overengineering?

The `install.packages()` function in R is the automatic unzipping utility that gets and install packages in R.

1. How do I find out what directory R has chosen to store packages?

2. How can I change the directory in which R stores and accesses packages?

Where does R store packages?

The <code>install.packages()</code> function in R is the automatic unzipping utility that gets and install packages in R.
<ol>
<li>
How do I find out what directory R has chosen to store packages?
</li>
<li>
How can I change the directory in which R stores and accesses packages?
</li>
</ol>

Is there a way to import data from a JSON file into R? More specifically, the file is an array of JSON objects with string fields, objects, and arrays. The RJSON Package isn&#39;t very clear on how to deal with this http://cran.r-project.org/web/packages/rjson/rjson.pdf.

Importing data from a JSON file into R

Does anyone have examples/tutorials of exception handling in R? The official documentation is very terse. 

Exception handling in R

I just finished reading about [scoping in the R intro][1], and am very curious about the `&lt;&lt;-` assignment.

The manual showed one (very interesting) example for `&lt;&lt;-`, which I feel I understood. What I am still missing is the context of when this can be useful.

So what I would love to read from you are examples (or links to examples) on when the use of `&lt;&lt;-` can be interesting/useful.  What might be the dangers of using it (it looks easy to loose track of), and any tips you might feel like sharing.


  [1]: http://cran.r-project.org/doc/manuals/R-intro.html#Scope

How do you use &quot;&lt;&lt;-&quot; (scoping assignment) in R?

I&#39;m trying to write a function to accept a data.frame (`x`) and a `column` from it. The function performs some calculations on x and later returns another data.frame. I&#39;m stuck on the best-practices method to pass the column name to the function.

The two minimal examples `fun1` and `fun2` below produce the desired result, being able to perform operations on `x$column`, using `max()` as an example. However, both rely on the seemingly (at least to me) inelegant 

1. call to `substitute()` and possibly `eval()` 
2. the need to pass the column name as a character vector. 

&lt;!--&gt;

    fun1 &lt;- function(x, column){
      do.call(&quot;max&quot;, list(substitute(x[a], list(a = column))))
    }

    fun2 &lt;- function(x, column){
      max(eval((substitute(x[a], list(a = column)))))
    }

    df &lt;- data.frame(B = rnorm(10))
    fun1(df, &quot;B&quot;)
    fun2(df, &quot;B&quot;)

I would like to be able to call the function as `fun(df, B)`, for example. Other options I have considered but have not tried:

 - Pass `column` as an integer of the column number. I think this would avoid `substitute()`. Ideally, the function could accept either.
 - `with(x, get(column))`, but, even if it works, I think this would still require `substitute` 
 - Make use of `formula()` and `match.call()`, neither of which I have much experience with.

*Subquestion*: Is `do.call()` preferred over `eval()`?



Pass a data.frame column name to a function

I&#39;m having trouble with a data frame and couldn&#39;t really resolve that issue myself:&lt;br&gt;
The &lt;b&gt;dataframe&lt;/b&gt; has arbitrary &lt;b&gt;properties as columns&lt;/b&gt; and &lt;b&gt;each row&lt;/b&gt; represents one &lt;b&gt;data set&lt;/b&gt;.&lt;p&gt;
The question is:&lt;br&gt;
How to &lt;b&gt;get rid of columns where for &lt;i&gt;ALL&lt;/i&gt; rows the value is NA&lt;/b&gt;?


Remove columns from dataframe where ALL values are NA

Is there a package naming convention for Python like Java&#39;s `com.company.actualpackage`? Most of the time I see simple, potentially colliding package names like &quot;[web][1]&quot;.

If there is no such convention, is there a reason for it? What do you think of using the Java naming convention in the Python world?


  [1]: http://webpy.org/

Python package name conventions

In order to be able to compare two versions of a package, I need to able to choose which version of the package that I load.  R&#39;s package system is set to by default to overwrite existing packages, so that you always have the latest version.  How do I override this behaviour?

My thoughts so far are:

I could get the package sources, edit the descriptions to give different names and build, in effect, two different packages.  I&#39;d rather be able to work directly with the binaries though, as it is much less hassle.

I don&#39;t necessarily need to have both versions of the packages loaded at the same time (just installed somewhere at the same time).  I could perhaps mess about with `Sys.getenv(&#39;R_HOME&#39;)` to change the place where R installs the packages, and then `.libpaths()` to change the place where R looks for them.  This seems hacky though, so does anyone have any better ideas?

How do you use multiple versions of the same R package?

OK here&#39;s what I would like: in the Eclipse package explorer, I see the following: (dot represents a clickable arrow that I can use to expand the folder)

&lt;ul&gt;
&lt;li&gt;PROJECT
&lt;ul&gt;&lt;li&gt; Source Folder 
         &lt;ul&gt;&lt;li&gt;Package
&lt;ul&gt; Class &lt;/ul&gt;&lt;li&gt;Package.SubPackage&lt;ul&gt;Foo&lt;/ul&gt;&lt;ul&gt;Bar&lt;/ul&gt;&lt;li&gt;Package.OtherSubPackage&lt;li&gt;Package.OtherSubPackage.VerySubPackage
&lt;li&gt;OtherPackage &lt;ul&gt; Foobar &lt;/ul&gt;&lt;li&gt; OtherPackage.SubPackage
&lt;ul&gt; Baz&lt;/ul&gt;&lt;/ul&gt;&lt;/ul&gt;&lt;/ul&gt;&lt;/ul&gt;


Long story short, I want to have many packages, each with many subpackages, in a source folder (and several source folders, so making more won&#39;t solve the problem)--so on the order of a couple hundred packages per source folder--ten to twenty packages each with fifteen subpackages. Therefore, I want the hierarchy to look like this:

&lt;ul&gt;
&lt;li&gt;PROJECT
&lt;ul&gt;&lt;li&gt; Source Folder 
         &lt;ul&gt;&lt;li&gt;Package
&lt;ul&gt; Class
&lt;li&gt;Package.SubPackage
&lt;ul&gt; Foo&lt;/ul&gt;
&lt;ul&gt;Bar&lt;/ul&gt;&lt;li&gt;Package.OtherSubPackage&lt;ul&gt;&lt;li&gt;Package.OtherSubPackage.VerySubPackage&lt;/ul&gt;&lt;/ul&gt;&lt;/ul&gt;
&lt;ul&gt;&lt;li&gt;OtherPackage &lt;ul&gt; Foobar
&lt;li&gt; OtherPackage.SubPackage
&lt;ul&gt; Baz&lt;/ul&gt;&lt;/ul&gt;&lt;/ul&gt;&lt;/ul&gt;&lt;/ul&gt;


so I can open or close a package and see a list of subpackages instead of having package and subpackage all at the same level in the hierarchy--which again makes far too many packages simultaneously displayed. Note this is *not* a question about filesystem; the file system works fine as far as I can tell--it is only a question about the _visual display_ in the Eclipse package explorer.

So: is there a way to add levels to the hierarchy? Thanks!! (Eclipse Helios on OS X 10.6)

How to view hierarchical package structure in Eclipse package explorer

I use some .sty-files that are not part of texlive and want to have them in a subdirectory of the folder with my main.tex. I used the following line to load the package:

    \usepackage{sty/prettythesis}

This works, but compiling the main.tex with xelatex and using [rubber][1] gives me a warning:

    sty/prettythesis.sty: You have requested package `sty/prettythesis&#39;,
    but the package provides `prettythesis&#39;. (page 1)

Is there a way to prevent this warning or handle this case without having to include &quot;sty\&quot; in all .sty-files&#39; \ProvidesPackage command or set the TEXINPUTS environment variable (which seems not to be possible from the main.tex itself)?


  [1]: https://launchpad.net/rubber

How to load latex .sty files from a subdirectory?

I seem to be sharing a lot of code with coauthors these days. Many of them are novice/intermediate R users and don&#39;t realize that they have to install packages they don&#39;t already have.

Is there an elegant way to call `installed.packages()`, compare that to the ones I am loading and install if missing?

Content Type	Original Author	Original Content on Stackoverflow
Question	Milktrader	View Question on Stackoverflow
Solution 1 - R	James Thompson	View Answer on Stackoverflow
Solution 2 - R	Dirk Eddelbuettel	View Answer on Stackoverflow
Solution 3 - R	Milktrader	View Answer on Stackoverflow
Solution 4 - R	Dave	View Answer on Stackoverflow

Where does R store packages?

R Problem Overview

R Solutions

Solution 1 - R

Solution 2 - R

Solution 3 - R

Solution 4 - R

First-time database design: am I overengineering?

PostgreSQL naming conventions

Attributions