Wikipedia:Reference desk/Archives/Computing/2009 September 12

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September 12

Producing an optimal route on Google Maps

I'm planning to visit a specific group of locations in the near future, but as I've never visited most of them before, I don't know the shortest order in which to visit them. I have coordinates (all are National Register of Historic Places sites, with coordinates taken from lists such as National Register of Historic Places listings in Mercer County, Ohio), so I'm interested in a way to put coords into Google to produce a route map. I know how to put coords into Google and get a route between them, but is it possible to give it coordinates for all sites and have it give me an order in which to visit them? If not, are there any free websites that have this option? Nyttend (talk) 03:38, 12 September 2009 (UTC)

In case it's at all helpful — I've put together a list here, and Toolserver is working fast enough that the geogrouptemplate is plotting everything properly on Google Maps. Locations, but not the shortest roads between them. Nyttend (talk) 05:19, 12 September 2009 (UTC)

What you're asking for -- an optimal route to visit n different destinations -- is an instance of the Traveling Salesman problem, which is one of the classic examples of an NP-complete computation problem. These problems become intractable fast as n increases. However, they can frequently be approximated efficiently. I would be astounded if anyone is offering a service to find the optimal route between n points, but there may be someone out there finding reasonably-good ones. --FOo (talk) 05:42, 12 September 2009 (UTC)

On modern computers solving the problem for up to something like 20 points can actually be done by a relatively simple dynamic programming algorithm. As long as we're talking about actual traveling between cities, a limit of 20 cities should be enough for just about anyone. Unfortunately user-friendly implementations of optimisation algorithms are a lot more expensive and rare than many other applications of computers. 84.239.160.214 (talk) 11:19, 12 September 2009 (UTC)

Country Specific Versions of MSN

My mate in the Gulf wants to download the Japanese version of MSN, with all of its emoticons and winks that are specific to the Japanese version. How does he do this? I already have the Japanese version, but the reason I do not know how to download it, is because I actually had no choice. I got it automatically, even though I am using a British PC, downloaded it from the UK, and used an email address that was created in the UK. Anyway, I don't mind, but my mate really wants to get it. How can he do this? --KageTora - (영호 (影虎)) (talk) 11:19, 12 September 2009 (UTC)

Have you tried downloading from the Japanese messenger website? --antilived^{T | C | G} 11:32, 12 September 2009 (UTC)

Thanks. He just tried that (after I told him your advice), and after a successful download and installation, he can't login. Does he need to make a new account? --KageTora - (영호 (影虎)) (talk) 13:20, 12 September 2009 (UTC)

I don't know but Microsoft might have a IP restriction for the Japanese Messenger. I, for example, can't use the mobile MSN available in China in NZ. --antilived^{T | C | G} 05:47, 13 September 2009 (UTC)

That can't be the problem, because I am in the UK now and I am having no problem with using the Japanese version, unless the Japanese version is specifically putting restrictions on IP addresses in the Middle East. I know what you mean, though, because I had trouble at first using MSN on my mobile (as it was only available in China and Taiwan) for a while, but that mysteriously cleared itself up. --KageTora - (영호 (影虎)) (talk) 17:12, 13 September 2009 (UTC)

MIDI playback in Python with real time MIDI events?

I'm trying to code a MIDI visualizer in Python (on Windows) using pygame, but I can't find anything helpful out there. There are a bunch of MIDI classes, but they're pretty damn old, very undocumented and as far as I can tell they're pretty much meant for dealing with controllers and synths. What I want is to get a local MIDI file, play it and have the means to "get" the events as they happen in sync with the music.

Am I asking for too much? I'm almost trying to code it myself using two different MIDI libraries I found, but that won't be much fun. Any light on this topic is much appreciated. Thanks! — Kieff | Talk 13:01, 12 September 2009 (UTC)

What does writing 'this' mean?

Often when I make a comment in an online forum someone replies with a "this". Only "this". I don't know what it means. What does it mean? From the context it seems like a good thing but I can't be sure. ReluctantPhilosopher (talk) 15:07, 12 September 2009 (UTC)

Can you link to an example? --KageTora - (영호 (影虎)) (talk) 15:10, 12 September 2009 (UTC)

I think something like

UserA: "We should all be worshipped as gods"
UserB: this

Yes they are complimenting or agreeing with you, - similar to QFR "Quoted for truth". At least that what I think it means.83.100.250.79 (talk) 15:16, 12 September 2009 (UTC)

clarify Actually I think it's used to draw attention to a post - so if you said something really stupid they might use "this" too.. 83.100.250.79 (talk) 15:18, 12 September 2009 (UTC)

Ah OK that's probably the right explanation - I was expecting something like that. Thanks! :) ReluctantPhilosopher (talk) 16:15, 12 September 2009 (UTC)

I have frequently seen it used to mean "I agree", and never to mean "look at this stupid post", but usage is likely to vary between forums, what with them being worlds unto themselves. 213.122.35.3 (talk) 17:02, 12 September 2009 (UTC)

How strange and not straightforward... I haven't seen that before, though, I guess there's a lot one doesn't see... --98.217.14.211 (talk) 18:01, 12 September 2009 (UTC)

According to this, it means "I agree". It might come from this - is this used often as a keyword? Zain Ebrahim (talk) 18:51, 12 September 2009 (UTC)

Yes, I think javascript (the 'language of the internet') also has a 'this' word [1], so I wouldn't be suprised that that is its origin.83.100.250.79 (talk) 19:00, 12 September 2009 (UTC)

Though that doesn't make much sense to me, as someone who has used it... You always do something with "this", you never use it alone. It would be one thing if they did something like this->awesome, or this.agree();, which would be dorky enough, but just "this"? Meaningless... --98.217.14.211 (talk) 19:24, 12 September 2009 (UTC)

Haha that is dorky for sure (I've done C programming). Anyways here is the latest thread on which 'this' was used and which led me here if you are curious: "this" in use ReluctantPhilosopher (talk) 20:56, 12 September 2009 (UTC)

I'm guessing this is simply an abbreviation of this is true. --70.253.156.55 (talk) 22:02, 13 September 2009 (UTC)

Disc CleanUp

Disc clean up in windows XP 'compresses old files'.What does this mean ? and does this in any way harm or remove the said file? Shraktu (talk) 20:24, 12 September 2009 (UTC)

It finds files that it thinks you don't access often and uses data compression on them to make them smaller. This has the downside of making accessing them slower and requiring more CPU activity than otherwise. Disk space is very cheap, so I wouldn't recommend doing this unless you're really short of space. -- Finlay McWalter • Talk 20:27, 12 September 2009 (UTC)

As a sidenote, compression doesn't always make access slower because it might be the hd and not the cpu that is the bottleneck. Anyway in a general case like this it probably will. --194.197.235.240 (talk) 21:31, 12 September 2009 (UTC)