R for the web

May 27, 2011

(This article was first published on binfalse » R, and kindly contributed to R-bloggers)

There is a nice R module for apache: rApache. So you can easily publish statistics.

To install rApache first install the following packages from the Debian/Ubuntu repository:

1	aptitude install apache2 apache2-mpm-prefork apache2-prefork-dev r-base-dev

So the basics are done. Lets install rApache. Grab the latest version:

1	wget http://biostat.mc.vanderbilt.edu/rapache/files/rapache-latest.tar.gz

extract the contents and cd into it. The installation process should be clear, I had to give a hint for the apxs2 location:

1
2
3

./configure --with-apxs=/usr/bin/apxs2
make
make install

To notify apache about the new module you need to create two more files. First one is /etc/apache2/mods-available/r.conf:

1
2
3
4
5
6
7
8
9

<Location /R>
ROutputErrors
SetHandler r-script
RHandler sys.source
</Location>

<Location /RApacheInfo>
SetHandler r-info
</Location>

Now all files in /R are assumed to be R-scripts, in /RApacheInfo you’ll find some information about your installation.
The second file is /etc/apache2/mods-available/r.load:

1	LoadModule R_module /usr/lib/apache2/modules/mod_R.so

This file just defines which lib to load.
To finish the installation you need to load the rApache module and restart the webserver via:

1 2	a2enmod r /etc/init.d/apache2 restart

That’s it. You can test whether all was successful by browsing to localhost/RApacheInfo, hopefully you’ll see some config stuff. To prepare some own tests create a directory /var/www/R (assuming your document-root is /var/www) and paste something like this in a file called test:

1 2	y = rnorm(100) print(y)

Browsing to localhost/R/test you should see something like this:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

[1] -0.4969626136 -0.0004799614 1.3858672447 -0.1888848545 0.5577465024
[6] -0.6463581808 1.3594363388 1.8160182284 -1.8602721944 0.3249432873
[11] 1.0861606647 -0.5075055497 -0.5152062853 0.4851131375 0.2924883195
[16] -0.5542238124 1.2741001461 0.2627202474 -0.8986869795 -0.8628182849
[21] -0.0788598913 0.4843055866 -0.2747585510 -1.1928500793 1.6193763442
[26] 0.3452218627 0.9518228897 -0.5858433386 1.9585346877 -0.2582043114
[31] -1.7989436202 1.2713761553 0.9045031014 -0.3456065867 0.3739555330
[36] 0.7512315203 -0.5289340037 -0.7700091217 -1.5103278314 -1.5195628428
[41] -0.8100795062 1.1027597227 0.0194147933 0.7819879165 -0.3914496199
[46] -0.4650911293 0.5889685176 -0.9659270213 1.0570030616 -0.0657166412
[51] -0.2077095857 0.6421821337 -0.1911934111 -3.1567052058 0.2704713187
[56] -0.5154689593 0.0923834868 -1.2100314635 0.6693369266 -1.2093881229
[61] 1.6755264101 1.2151146432 0.6683583636 -0.2982231602 1.4830922366
[66] 1.6505026636 -0.1769048244 0.3516470621 -0.0053594481 -0.3776870673
[71] -0.4797554602 1.2207702646 1.2762816419 -2.6137169267 -1.4423704831
[76] -0.4251822440 0.8007722424 -0.4985947758 -2.0685396392 -1.6844317212
[81] -0.2509955532 0.7906569225 -0.1259848747 -0.1352738978 -1.4943405839
[86] -2.4272199144 -0.5778250558 1.2579971393 -1.0476874144 0.2305160769
[91] -0.2920446292 0.1823053837 1.8858770756 1.4158084170 -1.2539321864
[96] 1.2667650232 0.1272379338 1.2726069769 0.8745111042 0.3848103655

To create a graphic you need to change the content type to an image type. A small example might give you an idea:

1
2
3
4
5
6
7
8

setContentType ("image/png")
temp <- tempfile ()
y = rnorm (100)
png (temp, type="cairo")
plot (1:100, y, t='l')
dev.off ()
sendBin (readBin (temp, 'raw', n=file.info(temp)$size))
unlink (temp)

Reload the page and you’ll see a more or less nice plot :-P
That’s it for the moment, for a more interactive interface take a look at the ggplot2 mod.

Download:
R: web-image.R
(Please take a look at the man-page)

To leave a comment for the author, please follow the link and comment on his blog: binfalse » R.