Category Archives: Uncategorized

data mining for oil sources

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Jon Udell writes about where the US gets its oil (the majority comes from Canada, not the middle east). He follows the data with the story of how he discovered the answer and presented the data using DabbleDB.

I agree with Jon when he says “we’re really close to the point where non-specialists will be able to find data online, ask questions of it, produce answers that bear on public policy issues, and share those answers online for review and discussion.” It’ll likely need another generation of tools before we work out the glitches and hiccups in the data flow and it’ll require the generation who grew up with the web to expect such tools at their fingertips and put them to use. I look forward to seeing what comes next.

animated sorting algorithms

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David Martin, an assistant professor at Boston College, has published a fabulous sorting visualization (via HMK).

These should be a must-see for every computer science student. He includes some good notes about what we should be looking for and why we might care (excerpted below). Often people publish marvelous visualizations, but people who are new to the subject matter can miss key aspects of what they might learn from the detailed visual cues. It is great to see the combination here.

These visualizations are intended to:

* Show how each algorithm operates.
* Show that there is no best sorting algorithm.
* Show the advantages and disadvantages of each algorithm.
* Show that worse-case asymptotic behavior is not the deciding factor in choosing an algorithm.
* Show that the initial condition (input order and key distribution) affects performance as much as the algorithm choice.

The ideal sorting algorithm would have the following properties:

* Stable: Equal keys aren’t reordered.
* Operates in place, requiring O(1) extra space.
* Worst-case O(n·lg(n)) key comparisons.
* Worst-case O(n) swaps.
* Adaptive: Speeds up to O(n) when data is nearly sorted or when there are few unique keys.

There is no algorithm that has all of these properties, and so the choice of sorting algorithm depends on the application.

video and voice chat added to gmail

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InformationWeek reports on google’s new voice and video chat. Since I gotta check all all the new video tech, I dove right in. Hmm… who do I know who uses a gmail account who will be logged in right now?

So, I open gmail to check out my contacts, of which I have none. But, lo and behold, I can use my AOL buddy list. I sign in and ping my friend (name omitted to protect the innocent):

ultrasaurus03 (6:52:12 PM): yt?
friend (6:53:48 PM): Yes.
friend (6:53:51 PM): Youre’ okay with this?
friend (6:53:53 PM): “Your IM conversation with ultrasaurus03 will be saved in ultrasaurus03’s IM history in Gmail from now on. Learn more at http://x.aim.com/gmail.”

OK, kindly big brother google is now tracking my every thought. Not an issue for this experiment, but duly noted.

Friend agrees to participate in my random technology experience. I tell him to hang on and I choose the video option. Ack! now I need to install…

Good thing I’m running Windows XP. It actually takes more than a few seconds to install…

maybe a minute or so…

but then I need to restart my browser.

Whew! I’m back. I login to gmail… and …

oh, gee. Not only do I need to have XP, but my friend does too. Time to find another friend.

Ok, now I’ve pinged another friend (via AIM) who has XP. He signs up for a gmail account. We add each other to our buddy lists. Then he installs the software. Whew.

Now we’re ready to chat… after one weird interaction (or lack thereof):

We’re actually communicating:

It’s a bit weird that it doesn’t seem to know he doesn’t have a camera — I really don’t need a large blank box on my screen while we have an audio conversation, but the quality of the audio is really quite good. I’m using the sucky built-in mic on my laptop but it doesn’t seem to be an issue like it is on some systems.

The official Google blog says “Gmail voice and video chat will be rolled out globally over the next day or so for Macs and PCs” — that was 3 days ago and no Mac version yet, but it is good to hear it is coming.

Interesting that Google chose to use audio-video technology from Vidyo rather than the ubiquitous Flash video. I would guess the decision not to use Flash stemmed from the superior audio conversation experience, since they did go with Flash video for the Google video site.