Month: February 2007

No, that’s not good either

I wrote about some work I’ve been doing on the Waypoint Generator in Rants and Revelations » Getting there, still some collateral damage. In that, I said I wanted to do some more testing. Well, I did. I reloaded the entire DAFIF dataset. The test took 4 straight days to run, and that’s not including losing a day or so when my router lost its mind. And what this test told me is that the new algorithm for eliminating duplicate points is overzealous.
For instance, it classified two Canadian airports, CYEE Midland/Huronia and CNL8 Wyevale/Boker Field, as being the same. They’re actually nearly two nautical miles apart.

I was calling points the same if the types matched and they’re within 0.05 degrees latitude and 0.05 degrees longitude of each other. Unfortunately that is just about 3 nautical miles in the north/south direction, which this test has shown is too wide a net.

The problem is that I want to spot duplicates when a waypoint changes id, AND when they update the coordinates. I’ve seen places where they’ve updated the coordinates by half a degree, especially in the case of user-entered data.

I think what I’m going to have to do is trust that the coordinates aren’t going to change a whole bunch at the same time the id changes. So what I’ll do is call something a duplicate if it’s within 0.05 degrees if the ids match, but within 0.01 degrees if the ids don’t match. That’s less than a nautical mile, and it would be pretty odd to find two airports within a nautical mile of each other. (A lot less odd to find heliports or reporting points, unfortunately.)

Damn, this means another multi-day test run, unfortunately.

If your VCR is flashing 12:00…

I saw (and stole) a sig quote once that said “If your VCR is flashing 12:00, then maybe Linux isn’t the OS for you”. Today I had a similar experience.

I host a bunch of mailing lists on Mailman at my domain list.xcski.com. Some of them I run, and some, like the ones for the Linux Users Group of Rochester (LUGOR), I just host and let somebody else run. One of the things that Mailman does is automatically send out a monthly ‘password reminder’ – as well as reminding people that they belong to one or more mailing lists and giving them the password and url they need to know if they need to make changes to their subscription, it’s also a good way for Mailman to test if the address is still valid so it can unsubscribe invalid addresses automatically.

The monthly mailing list reminder looks like:


This is a reminder, sent out once a month, about your list.xcski.com
mailing list memberships. It includes your subscription info and how
to use it to change it or unsubscribe from a list.

You can visit the URLs to change your membership status or
configuration, including unsubscribing, setting digest-style delivery
or disabling delivery altogether (e.g., for a vacation), and so on.

In addition to the URL interfaces, you can also use email to make such
changes. For more info, send a message to the '-request' address of
the list (for example, mailman-request@DOMAINNAME) containing just
the word 'help' in the message body, and an email message will be sent
to you with instructions.

If you have questions, problems, comments, etc, send them to
mailman-owner@DOMAINNAME. Thanks!

Passwords for YOUR_EMAIL_ADDRESS:

List Password // URL
---- --------

followed by the name of each list you subscribe to, the password you use for that list, and the url to change your user options (or unsubscribe) for that list.

Frequently on the first of the month, I get an email or two from people who see these emails and rather than following the instructions and doing their own list maintenance, write to me and say “please unsubscribe me” or “please change my address to foo” or whatever, and I have a form letter that basically says “read the instructions and do it yourself”. But today I got a new variation:

It seems I have been added to this list by mistake. It looks as though this
address was found from the lugor mailing list. Please remove me from the
xcski mailing list.

My response was along the lines of “If you can’t tell the difference between a domain name and a list name, maybe Linux isn’t the OS for you.” Harsh, maybe, but hey, it amuses me and I get so few pleasures from mailing list hosting.