Comments for Cerebral Mastication

Comment on Principal Component Analysis (PCA) vs Ordinary Least Squares (OLS): A Visual Explanation by JD Long

JD Long — Wed, 07 Dec 2011 13:07:56 +0000

Matt, thanks for catching the typo!

I enjoy writing in the tone of “on the couch with a beer.” I find it helps simple things seem simple and complex things seem approachable. Writing formally as if in a journal article tends to make simple things seem obfuscated and complex things impossible… at least that’s my experience. Thanks for reading.

Comment on Principal Component Analysis (PCA) vs Ordinary Least Squares (OLS): A Visual Explanation by Matt

Matt — Wed, 07 Dec 2011 02:18:29 +0000

Typo in the line after the first picture. “Two of these errors are illustrated for the x ~ y case in the following picture” Should be “y ~ x”, as that is the red line.

Nice post, interesting stuff and appreciate the “sitting on the couch with a beer” tone of your writing ^_^

Comment on Fast Two Way Sync in Ubuntu! by Keep your files in sync between computers for free | Decision Science News

Keep your files in sync between computers for free | Decision Science News — Sun, 20 Nov 2011 04:13:12 +0000

[...] uses lsyncd to keep his R files (specifically, R Studio output) in sync with his local machine. Post 1. Post 2. At DSN, we use lsyncd to create a magic folder on our server that pushes R plots generated [...]

Comment on Connecting to SQL Server from R using RJDBC by sk

sk — Fri, 18 Nov 2011 17:04:58 +0000

this post helped me lot – thanks!
only the sqljdbc4.jar is really needed, maybe this is worth mentioning as well (for people being even more spooked by java than you). anyway – thanks again!

Comment on Details of two-way sync between two Ubuntu machines by Nick P.

Nick P. — Tue, 08 Nov 2011 20:15:08 +0000

Thanks for replying so fast, i have already found a solution to this. So i post it in case come in handy to someone else. The problem was that the lsyncd daemon is launched using root priviledges. So ssh was preventing access to my .ssh rsa files of my simple user account.

I just generated ssh keys for root account like this:

$ ssh-keygen
(type enter to all default options)
$ cat ~/.ssh/id_rsa.pub | ssh @ ‘cat >> .ssh/authorized_keys’

After that, your setup works like a charm!!!

Comment on Details of two-way sync between two Ubuntu machines by JD Long

JD Long — Tue, 08 Nov 2011 20:02:35 +0000

Ugh… nothing jumps out at me as to why this is happening. Sorry that I’m not much help. Try looking at the lsyncd logs and possibly upping the level of verbosity of the logging.

Comment on Details of two-way sync between two Ubuntu machines by Nick P.

Nick P. — Tue, 08 Nov 2011 17:37:25 +0000

Hello, very nice and interesting article!! I have followed your tutorial in order to apply it in two servers but i have a problem with lsyncd daemon in /init.d/. I have Ubuntu server (oneiric) installed.

My problem is that even if i have set up private keys for ssh in both servers, i get the following error in lsyncd.log file:

Contacting server…
Permission denied, please try again.
Permission denied, please try again.
Permission denied (publickey,gssapi-with-mic,password).
Fatal error: Lost connection with the server

It seems strange since when i run the command of the lsyncd.config file (i.e /usr/bin/unison -batch /home/jal/Documents ssh://12.34.56.78//home/jal/Documents) it connects to ssh without password (using ssh keys) and performs the synchronization just fine.

Any ideas?

P.S my ~/.ssh permissions are 755

Comment on Details of two-way sync between two Ubuntu machines by JD Long

JD Long — Mon, 01 Aug 2011 17:21:47 +0000

Bruno, I bet this is happening to me and I didn’t realize it. I suspect I just saw Unison running and assumed that was the daemon. I agree it’s less than ideal.

Comment on Details of two-way sync between two Ubuntu machines by Bruno Leon

Bruno Leon — Mon, 01 Aug 2011 17:18:43 +0000

They are launched in series not parallel.
I also found out that if you create / delete / recreate a file within the agregate period, only on unison shell is spawned.

This tend to show that events are aggregated when they belong to the same file.
Different file events for files in the same folder do not agregate though.

This is no blocking issue because it works, but still having unison launched for nothing is just not ideal.

Comment on Details of two-way sync between two Ubuntu machines by JD Long

JD Long — Mon, 01 Aug 2011 17:03:05 +0000

Bruno, I set a wait period of ~ 15 seconds. It appears that having a wait period works like an aggregation. I’m not seeing a huge number of Unison events stack up. This may be some logic in Unison that’s helping me out. Are you seeing Unison run 100 times in parallel or is it running unison 100 times in series? It may be possible that I’m getting Unison events in series and I don’t realize it.