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• How to contain the Deepwater Horizon oil spill? [closed]

  - by Yarin

  This is obviously not programming, but it's important and we're smart people, so let's give it a shot. (BP has actually begun soliciting suggestions for how to deal with the crisis http://www.deepwaterhorizonresponse.com/go/doc/2931/546759/, confirming that they don't have a clue) I'll start with my own proposal... Anchored Chute: A large-diameter, collapsible, flexible tube/hose with a wide mouth on one end is anchored over the leak. There's no need for a hermetic seal, the opening just needs to be big enough to form a canopy over the leak area. The rest of the tubing can just be dumped on the sea floor. Since oil is denser than water, the oily water that flows into the mouth eventually inflates the tube and raises the opposite end to the surface, where it can be collected (Like those inflatable dancing air socks at car dealerships). Further buoyancy could be added with floats attached to the tube at intervals. I think this method would not be as susceptible to the problems BP had with the containment dome, where a rigid, metal casing froze up with crystallized hydrates, as we would not be trying to contain the full pressure of the well, but would be using the natural buoyancy of the oil to channel its flow, and with a much larger opening.

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• Select all points in a matrix within 30m of another point

  - by pinnacler

  So if you look at my other posts, it's no surprise I'm building a robot that can collect data in a forest, and stick it on a map. We have algorithms that can detect tree centers and trunk diameters and can stick them on a cartesian XY plane. We're planning to use certain 'key' trees as natural landmarks for localizing the robot, using triangulation and trilateration among other methods, but programming this and keeping data straight and efficient is getting difficult using just Matlab. Is there a technique for sub-setting an array or matrix of points? Say I have 1000 trees stored over 1km (1000m), is there a way to say, select only points within 30m radius of my current location and work only with those? I would just use a GIS, but I'm doing this in Matlab and I'm unaware of any GIS plugins for Matlab. I forgot to mention, this code is going online, meaning it's going on a robot for real-time execution. I don't know if, as the map grows to several miles, using a different data structure will help or if calculating every distance to a random point is what a spatial database is going to do anyway. I'm thinking of mirroring two arrays, one sorted by X and the other by Y. Then bubble sorting to determine the 30m range in that. I do the same for both arrays, X and Y, and then have a third cross link table that will select the individual values. But I don't know, what that's called, how to program that and I'm sure someone already has so I don't want to reinvent the wheel. Cartesian Plane GIS

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• Fetch main model and translations in one query with globalize2

  - by J. Pablo Fernández

  Is there a way to fetch the model and the translations in one query when using globalize2? For example, having a model called Language which have two fields, code and name of which the second is translatable I do the following: en = Language.find_by_code("en") and it runs this query: SELECT SQL_NO_CACHE * FROM `languages` WHERE (`languages`.`code` = 'en') LIMIT 1 and when I do: en.name it runs: SELECT SQL_NO_CACHE * FROM `language_translations` WHERE (`language_translations`.language_id = 123 AND (`language_translations`.`locale` IN ('en','root'))) and if I do it again it'll re-run the query. Is there a way to fetch all the translated data in the first query? I've tried: en = Language.find_by_code("en", :joins => "JOIN language_translations ON language_translations.language_id = languages.id") but it made no difference. UPDATE: this is being discussed as an issue in globalize2: http://github.com/joshmh/globalize2/issues/#issue/33

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• When is it good to start using project management applications?

  - by Mr.Gando

  Hello, I was wondering, when is the right time or the correct project size to start using project management applications ( like Redmine or Trac ). I have a serious project, for now it's only me developing, but I use redmine to set my project versions, issues, and estimations. I think it's a good idea, because you never know when somebody else is going to join the team, and also allows me to organize myself effectively. I ask this question because I was Teaching Assistant at my university for one year in a row for a course, and I got questions about this very very often. While I'm a believer of the KISS principle, I think that learning to use this tools early is a win-win most of the time. I really believe that we can avoid this question to become argumentative, and that there's somewhat of a consensus about this issue, which I consider quite important in todays software development world. So, when is the right time ? what is the correct project/team size ?

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• MySQL, how can I SELECT WHERE one field value doesn't occurs in another?

  - by Jules

  I'm trying to do a search on my test server, speed isn't so important. I want to find if a phrase, the whole contents of one field, occurs in any part (as a whole) doesn't occur in another field. Heres my current query which finds if the phrase does occur SELECT pads.padid, pads.programname, keywords.word FROM Pads JOIN keywords ON Pads.Padid = keywords.Padid WHERE pads.Programname = keywords.word AND RemoveMeDate = '2001-01-01 00:00:00' My problem is that the field word contains other words too. I need to produce a count of where there isn't a keywords record with keywords.word equal to pads.programname ? EDIT: So if I have these records Pads: PadID=3 ProgramName=my prog PadID=4 ProgramName=Bad prog PadID=5 ProgramName=Good prog PadID=6 ProgramName=other prog Keywords: PadID=3 word=fox prog PadID=3 word=pig prog PadID=4 word=big prog PadID=4 word=nice prog PadID=5 word=fox prog PadID=6 word=bad prog PadID=6 word=fox prog The query I want would retun a count of 3 and record 6 has bad prog

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• When to choose which machine learning classifier?

  - by LM

  Suppose I'm working on some classification problem. (Fraud detection and comment spam are two problems I'm working on right now, but I'm curious about any classification task in general.) How do I know which classifier I should use? (Decision tree, SVM, Bayesian, logistic regression, etc.) In which cases is one of them the "natural" first choice, and what are the principles for choosing that one? Examples of the type of answers I'm looking for (from Manning et al.'s "Introduction to Information Retrieval book": http://nlp.stanford.edu/IR-book/html/htmledition/choosing-what-kind-of-classifier-to-use-1.html): a. If your data is labeled, but you only have a limited amount, you should use a classifier with high bias (for example, Naive Bayes). [I'm guessing this is because a higher-bias classifier will have lower variance, which is good because of the small amount of data.] b. If you have a ton of data, then the classifier doesn't really matter so much, so you should probably just choose a classifier with good scalability. What are other guidelines? Even answers like "if you'll have to explain your model to some upper management person, then maybe you should use a decision tree, since the decision rules are fairly transparent" are good. I care less about implementation/library issues, though. Also, for a somewhat separate question, besides standard Bayesian classifiers, are there 'standard state-of-the-art' methods for comment spam detection (as opposed to email spam)? [Not sure if stackoverflow is the best place to ask this question, since it's more machine learning than actual programming -- if not, any suggestions for where else?]

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• Understanding Thread/BeginInvoke? [beginner]

  - by Moberg

  Consider the code: class Work { public void DoStuff(string s) { Console.WriteLine(s); // .. whatever } } class Master { private readonly Work work = new Work(); public void Execute() { string hello = "hello"; // (1) is this an ugly hack ? var thread1 = new Thread(new ParameterizedThreadStart(o => this.work.DoStuff((string)o))); thread1.Start(hello); thread1.Join(); // (2) is this similar to the one above? new Action<string>(s => this.work.DoStuff(s)).BeginInvoke(hello, null, null); } } Is (1) an acceptable way of easy starting some work in a seperate thread? If not a better alternative would be much appreciated. Is (2) doing the same? I guess what I ask is if a new thread is started, or.. Hope you can help a beginner to a better understanding :) /Moberg

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• jQuery tag editor function

  - by Mad Hatter

  I'm using jQuery Tag Editor (http://blog.crazybeavers.se/wp-content/demos/jquery.tag.editor/) for a school project. Everything works perfect, but i'm not able to retrieve the array of tags that I added. This is my code: $("#allTags").click(function () { var tags = $("#tagEditor").tagEditor().getTags(); alert(tags); }); The array doesn't return anything. This is the code from the jQuery Tag Editor: (function ($) { $.fn.extend({ tagEditor: function (options) { var defaults = { separator: ',', items: [], className: 'tagEditor', confirmRemoval: false, confirmRemovalText: 'Do you really want to remove the tag?', completeOnSeparator: false, completeOnBlur: false, initialParse: true, } var options = $.extend(defaults, options); var listBase, textBase = this, hiddenText; var itemBase = []; this.getTags = function () { return itemBase.join(options.separator); }; ...

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• Not able to pass multiple override parameters using nose-testconfig 0.6 plugin in nosetests

  - by Jaikit

  Hi, I am able to override multiple config parameters using nose-testconfig plugin only if i pass the overriding parameters on commandline. e.g. nosetests -c nose.cfg -s --tc=jack.env1:asl --tc=server2.env2:abc But when I define the same thing inside nose.cfg, than only the value for last parameter is modified. e.g. tc = server2.env2:abc tc = jack.env1:asl I checked the plugin code. It looks fine to me. I am pasting the part of plugin code below: parser.add_option( "--tc", action="append", dest="overrides", default = [], help="Option:Value specific overrides.") configure: if options.overrides: self.overrides = [] overrides = tolist(options.overrides) for override in overrides: keys, val = override.split(":") if options.exact: config[keys] = val else: ns = ''.join(['["%s"]' % i for i in keys.split(".") ]) # BUG: Breaks if the config value you're overriding is not # defined in the configuration file already. TBD exec('config%s = "%s"' % (ns, val)) Let me know if any one has any clue.

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• Is using os.path.abspath to validate an untrusted filename's location secure?

  - by mcmt

  I don't think I'm missing anything. Then again I'm kind of a newbie. def GET(self, filename): name = urllib.unquote(filename) full = path.abspath(path.join(STATIC_PATH, filename)) #Make sure request is not tricksy and tries to get out of #the directory, e.g. filename = "../.ssh/id_rsa". GET OUTTA HERE assert full[:len(STATIC_PATH)] == STATIC_PATH, "bad path" return open(full).read() Edit: I realize this will return the wrong HTTP error code if the file doesn't exist (at least under web.py). I will fix this.

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• Joining different models in Django

  - by Andrew Roberts

  Let's say I have this data model: class Workflow(models.Model): ... class Command(models.Model): workflow = models.ForeignKey(Workflow) ... class Job(models.Model): command = models.ForeignKey(Command) ... Suppose somewhere I want to loop through all the Workflow objects, and for each workflow I want to loop through its Commands, and for each Command I want to loop through each Job. Is there a way to structure this with a single query? That is, I'd like Workflow.objects.all() to join in its dependent models, so I get a collection that has dependent objects already cached, so workflows[0].command_set.get() doesn't produce an additional query. Is this possible?

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• Using a "vo" for joined data?

  - by keithjgrant

  I'm building a small financial system. Because of double-entry accounting, transactions always come in batches of two or more, so I've got a batch table and a transaction table. (The transaction table has batch_id, account_id, and amount fields, and shared data like date and description are relegated to the batch table). I've been using basic vo-type models for each table so far. Because of this table structure structure, though, transactions will almost always be selected with a join on the batch table. So should I take the selected records and splice them into two separate vo objects, or should I create a "shared" vo that contains both batch and transaction data? There are a few cases in which batch records and/or transaction records. Are there possible pitfalls down the road if I have "overlapping" vo classes?

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• How to select DISTINCT rows without having the ORDER BY field selected

  - by JannieT

  So I have two tables students (PK sID) and mentors (PK pID). This query SELECT s.pID FROM students s JOIN mentors m ON s.pID = m.pID WHERE m.tags LIKE '%a%' ORDER BY s.sID DESC; delivers this result pID ------------- 9 9 3 9 3 9 9 9 10 9 3 10 etc... I am trying to get a list of distinct mentor ID's with this ordering so I am looking for the SQL to produce pID ------------- 9 3 10 If I simply insert a DISTINCT in the SELECT clause I get an unexpected result of 10, 9, 3 (wrong order). Any help much appreciated.

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• Printing array with delimiters in Perl

  - by Mark B

  I have an array in Perl I want to print with space delimiters between each element, except every 10th element which should be newline delimited. There aren't any spaces in the elements if that matters. I've written a function to do it with for and a counter, but I wondered if there's a better/shorter/canonical Perl way, perhaps a special join syntax or similar. My function to illustrate: sub PrintArrayWithNewlines { my $counter = 0; my $newlineIndex = shift @_; foreach my $item (@_) { ++$counter; print "$item"; if($counter == $newlineIndex) { $counter = 0; print "\n"; } else { print " "; } } }

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• Making pygtksourceview work in windows

  - by Dani

  So, I'm trying to get gtksourceview python bindings work under windows (I'm developing a cross platform gtk application that shows code, so gtksourceview seemed like a natural choice). I have pygtk installed and working (I followed the instructions in http://www.pygtk.org/downloads.html) I tried the instructions in http://projects.gnome.org/gtksourceview/ for gtksourceview. Here is what I did: Downloaded and extracted the latest gtksourceview window binaries from: http://ftp.gnome.org/pub/gnome/binaries/win32/gtksourceview/2.10/gtksourceview-2.10.0.zip The website said gtksourceview needs libxml, so I downloaded and extracted the latest libxml window binaries from: http://xmlsoft.org/sources/win32/libxml2-2.7.6.win32.zip Added the folders containing dll files to the PATH (in my computer they were c:\opt\gtksourceview\bin; C:\opt\libxml2-2.7.6.win32\bin) Installed pygtksourceview with the windows installer: http://ftp.gnome.org/pub/gnome/binaries/win32/pygtksourceview/2.10/pygtksourceview-2.10.0.win32-py2.6.exe Renamed the file libxml2.dll to libxml2-2.dll (after running depends on the gtksourceview dll) Now, the gtksouceview widget seems to work, until I'm trying to set the code's language. When I do that python crashes. Here is how I crash it in the console (the simplest way i could come up with): >>>import gtksourceview2 >>>lang = gtksourceview2.language_manager_get_default().get_language('cpp') >>>lang.get_style_ids() I'm hoping I'm not the first person to use gtksourceview in python on windows. Any ideas what I should try?

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• A quick over view of facebook's db?

  - by Matt

  Hey guys I find it hard to believe that Facebook uses simple sql, surely it would use some other method but lets assume for now it does use sql how would the code assimilating the 'wall' work? Lets say that there is three tables (just for the example) Friends: id (entry key) - uid(your id) - fid (your mates' id) Wall:id (entry key) - username - comment - time - commentcount comments: id (entry key) - wid (wall id (original comment)) - reply - time Lets forget about the like part and report etc, as well as mod things (ip, ban etc.) How would this work? Select wall.id, wall.username, wall.comment, wall.time, wall.commentcount, comments.wid, comments.reply, comments.time FROM wall inner join comments ON wall.id=comments.wid ORDER BY wall.time; That's your own wall but how do they get friend's? A heap of unions?

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• Understanding MongoDB (and NoSQL in general) and how to make the best use of it

  - by Earlz

  Hello, I am beginning to think that my next project I am wanting to do would work better with a NoSQL solution. The project would either involve a ton of 2-column tables or a ton of dynamic queries with dynamically generated columns in a traditional SQL database. So I feel a NoSQL database would be much cleaner. I'm looking at MongoDB and it looks pretty promising. Anyway, I'm attempting to make sense of it all. Also, I will be using MongoMapper in Ruby. Anyway though, I'm confused as to how to layout things in such a freeform database. I've read http://stackoverflow.com/questions/2170152/nosql-best-practices and the answer there says that normalization is usually bad in a NoSQL DB. So how would be the best way of laying out say a simple blog with users, posts, and comments? My natural thought was to have three collections for each and then link them by a unique ID. But this apparently is wrong? So, what are some of the ways to lay out such a thing? My concern with the answer given in the other question is, what if the author's name changed? You'd have to go through updating a ton of posts and comments. But is this an okay thing to do with NoSQL?

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• Problem with update sql with excel

  - by phenevo

  Hi, I have a problem with this query: Update Provinces Set Provinces.DefaultName=T2.Defaultname from Provinces inner join OPENROWSET('Microsoft.Jet.OLEDB.4.0', 'Excel 8.0;Database=C:\provinces.xlsx;HDR=YES', 'SELECT Code, Defaultname FROM [Arkusz1$]') T2 On Provinces.Code = t2.Code where Provinces.Code = T2.Code I get error: Msg 7399, Level 16, State 1, Line 1 The OLE DB provider "Microsoft.Jet.OLEDB.4.0" for linked server "(null)" reported an error. The provider did not give any information about the error. Msg 7303, Level 16, State 1, Line 1 Cannot initialize the data source object of OLE DB provider "Microsoft.Jet.OLEDB.4.0" for linked server "(null)". What is a reason of this unpleasent situation ?

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• Deleting orphans with JPA

  - by homaxto

  I have a one-to-one relation where I use CascadeType.PERSIST. This has over time build up a huge amount of child records that has not been deleted, to such an extend that it is reflected in the performance. Now I wish to add some code that cleans up the database removing all the child records that are not referenced by a parent. At the moment we are talking 400K+ records, at I need to run the code on all customer installations just to be sure they do not run into the same problem. I think the best solution would be to run a named query (because we support two databases) that deletes the necessary records, and this is where I get into problems, because how should I write it in JPQL? The result I want can be defined like the following sql statement, which unfortunaltely does not run on MySQL. DELETE FROM child c1 WHERE c1.pk NOT IN (SELECT DISTINCT p.pk FROM child c2 JOIN parent p ON p.child = c2.pk);

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• Using game of life or other virtual environment for artificial (intelligence) life simulation? [clos

  - by Berlin Brown

  One of my interests in AI focuses not so much on data but more on biologic computing. This includes neural networks, mapping the brain, cellular-automata, virtual life and environments. Described below is an exciting project that includes develop a virtual environment for bots to evolve in. "Polyworld is a cross-platform (Linux, Mac OS X) program written by Larry Yaeger to evolve Artificial Intelligence through natural selection and evolutionary algorithms." http://en.wikipedia.org/wiki/Polyworld " Polyworld is a promising project for studying virtual life but it still is far from creating an "intelligent autonomous" agent. Here is my question, in theory, what parameters would you use create an AI environment? Possibly a brain environment? Possibly multiple self contained life organisms that have their own "brain" or life structures. I would like a create a spin on the game of life simulation. What if you have a 64x64 game of life grid. But instead of one grid, you might have N number of grids. The N number of grids are your "life force" If all of the game of life entities die in a particular grid then that entire grid dies. A group of "grids" makes up a life form. I don't have an immediate goal. First, I want to simulate an environment and visualize what is going on in the environment with OpenGL and see if there are any interesting properties to the environment. I then want to add "scarce resources" and see if the AI environment can manage resources adequately.

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• MySQL GROUP_CONCAT + IN() = missing data :-(

  - by Andrew Heath

  Example: Table: box boxID color 01 red 02 blue 03 green Table: boxHas boxID has 01 apple 01 pear 01 grapes 01 banana 02 lime 02 apple 02 pear 03 chihuahua 03 nachos 03 baby crocodile I want to query on the contents of each box, and return a table with each ID, color, and a column that concatenates the contents of each box, so I use: SELECT box.boxID, box.color, GROUP_CONCAT(DISTINCT boxHas.has SEPARATOR ", ") AS contents FROM box LEFT JOIN boxHas ON box.boxID=boxHas.boxID WHERE boxHas.has IN ('apple','pear') GROUP BY box.boxID ORDER BY box.boxID and I get the following table of results: boxID color contents 01 red apple, pear 02 blue apple, pear My question to you is: why isn't it listing ALL the has values in the contents column? Why is my WHERE statement also cropping my GROUP_CONCAT? The table I thought I was going to get is: boxID color contents 01 red apple, banana, grapes, pear 02 blue apple, lime, pear Although I want to limit my boxID results based upon the WHERE statement, I do not want to limit the contents field for valid boxes. :-/ Help?

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• Mercurial How To Merge 2 Repositories that share a common ancestor but are not clones of the same re

  - by sylvanaar

  I am using hg-subversion, and I have 2 different hg repositories one from our svn trunk, and one from a branch of the trunk. I would like to link them somehow. At some point in the history both Hg repositories will be identical is there some way to join them? In other words is there a way to relate the repositories from within Hg? The technique I am currently using is to just export the second repository over top of the working copy of the revision they share, and then commit that working copy as a branch in Hg, but I lose the history this way. Any advice would be great

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• Safe to KILL a mysql process REPLACEing records in a large myisam table?

  - by threecheeseopera

  I have a REPLACE query running for a few days now on a few MyISAM tables, the largest having 20+million records. I need it to stop. It is, basically: REPLACE INTO really_large_table (a,b,c,d) SELECT e,f,g,h FROM big_table INNER JOIN huge_table ON big_table.x LIKE CONCAT('%', huge_table.y, '%'); I need to KILL it, and I am worried that I may corrupt really_large_table. Because the sub-query itself takes a significant amount of time, the REPLACEing probably occurs (relatively) infrequently; if this is true, does this make it less likely for the data to become corrupted? For the curious, here is the SO question asked about the query I am trying to kill.

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• g++ and c++0x specification support

  - by SepiDev

  although it's been said that the support for c++0x new features in g++ are in experimental mode, many gcc developer claimed that you can use most of the new features in your codes and get the program to work. but when I try to compile this simple program it results in segmentation fault. Why? #include <thread> #include <iostream> void my_thread_func() { std::cout<<"hello"<<std::endl; } int main() { std::thread t(my_thread_func); t.join(); } g++ -std=c++0x -Wall -o run main.cc

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• List Directories and get the name of the Directory

  - by chrissygormley

  Hello, I am trying to get the code to list all the directories in a folder, change directory into that folder and get the name of the current folder. The code I have so far is below and isn't working at the minute. I seem to be getting the parent folder name. import os for directories in os.listdir(os.getcwd()): dir = os.path.join('/home/user/workspace', directories) os.chdir(dir) current = os.path.dirname(dir) new = str(current).split("-")[0] print new I also have other files in the folder but I do not want to list them. I have tried the below code but I haven't got it working yet either. for directories in os.path.isdir(os.listdir(os.getcwd())): Can anyone see where I am going wrong? Thanks

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