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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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• Ruby - calling constructor without arguments & removal of new line characters

  - by Raj

  I am a newbie at Ruby, I have written down a sample program. I dont understand the following: Why constructor without any arguments are not called in Ruby? How do we access the class variable outside the class' definition? Why does it always append newline characters at the end of the string? How do we strip it? Code: class Employee attr_reader :empid attr_writer :empid attr_writer :name def name return @name.upcase end attr_accessor :salary @@employeeCount = 0 def initiaze() @@employeeCount += 1 puts ("Initialize called!") end def getCount return @@employeeCount end end anEmp = Employee.new print ("Enter new employee name: ") anEmp.name = gets() print ("Enter #{anEmp.name}'s employee ID: ") anEmp.empid = gets() print ("Enter salary for #{anEmp.name}: ") anEmp.salary = gets() theEmpName = anEmp.name.split.join("\n") theEmpID = anEmp.empid.split.join("\n") theEmpSalary = anEmp.salary.split.join("\n") anEmp = Employee.new() anEmp = Employee.new() theCount = anEmp.getCount puts ("New employee #{theEmpName} with employee ID #{theEmpID} has been enrolled, welcome to hell! You have been paid as low as $ #{theEmpSalary}") puts ("Total number of employees created = #{theCount}") Output: Enter new employee name: Lionel Messi Enter LIONEL MESSI 's employee ID: 10 Enter salary for LIONEL MESSI : 10000000 New employee LIONEL MESSI with employee ID 10 has been enrolled, welcome to hell! You have been paid as low as $ 10000000 Total number of employees created = 0 Thanks

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• merging javascript arrays for json

  - by Nat

  I serially collect information from forms into arrays like so: list = {"name" : "John", "email" : "[email protected]", "country" : "Canada", "color" : "blue"}; identifier = "first_round"; list = {"name" : "Harry", "email" : "[email protected]", "country" : "Germany"}; identifier = "second_round"; I want to combine them into something (I may have braces where I need brackets) like: list_all = { "first_round" : {"name" : "John", "email" : "[email protected]", "country" : "Canada", "color" : "blue"} , "second_round" : {"name" : "Harry", "email" : "[email protected]", "country" : "Germany"} }; so I can access them like: alert(list_all.first_round.name) -> John (Note: the name-values ("name", "email", "color") in the two list-arrays are not quite the same, the number of items in each list-array is limited but not known in advance; I need to serially add only one array to the previous structure each round and there may be any number of rounds, i.e. "third-round" : {...}, "fourth-round" : {...} and so on.) Ultimately, I'd like it to be well-parsed for JSON. I use the jquery library, if that helps.

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• Facebook like button issue.

  - by Ross Hale

  Hello community, We're having some trouble getting our like button to work. It seemed to work last week but suddenly it's stopped working. Basically when clicking "Like", we get an error saying: You failed to provide a valid list of administators. You need to supply the administors using either a "fb:app_id" meta tag, or using a "fb:admins" meta tag to specify a comma-delimited list of Facebook users. Our section looks like this: <html xmlns="http://www.w3.org/1999/xhtml" xmlns:og="http://opengraphprotocol.org/schema/" xmlns:fb="http://www.facebook.com/2008/fbml" xml:lang="en" lang="en"> <head> <meta property="fb:app_id" content="number"/> <meta property="fb:admins" content="number"/> <meta property="og:title" content="title"/> <meta property="og:type" content="website"/> <meta property="og:url" content="url with trailing slash"/> <meta property="og:image" content="url to image"/> <meta property="og:site_name" content="Site Name"/> </head> Help?

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• How to reference other documents in a couchDB view (joining like functionality)

  - by Surfrdan

  We have a CouchDB representation of an XML database which we use to power a javascript based frontend for manipulating the XML documents. The basic structure is a simple 3 level hierachy. i.e. A - B - C A: Parent doucument (type A) B: any number of child documents of parent type A C: any number of child documents of parent type B We represent these 3 document types in CouchDB with a 'type' attribute: e.g. { "_id":"llgc-id:433", "_rev":"1-3760f3e01d7752a7508b047e0d094301", "type":"A", "label":"Top Level A document", "logicalMap":{ "issues":{ "1":{ "URL":"http://hdl.handle.net/10107/434-0", "FILE":"llgc-id:434" }, "2":{ "URL":"http://hdl.handle.net/10107/467-0", "FILE":"llgc-id:467" etc... } } } } { "_id":"llgc-id:433", "_rev":"1-3760f3e01d7752a7508b047e0d094301", "type":"B", "label":"a B document", } What I want to do is produce a view which returns documents just like the A type but includes the label attribute from the B document within the logicalMap list e.g. { "_id":"llgc-id:433", "_rev":"1-3760f3e01d7752a7508b047e0d094301", "type":"A", "label":"Top Level A document", "logicalMap":{ "issues":{ "1":{ "URL":"http://hdl.handle.net/10107/434-0", "FILE":"llgc-id:434", "LABEL":"a B document" }, "2":{ "URL":"http://hdl.handle.net/10107/467-0", "FILE":"llgc-id:467", "LABEL":"another B document" etc... } } } } I'm struggling to get my head around the best way to perform this. It looks like it should be fairly simple though!

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• problem with binarysearch algorithm

  - by arash

  hi friends,the code below belongs to binary search algorithm,user enter numbers in textbox1 and enter the number that he want to fing with binarysearch in textbox2.i have a problem with it,that is when i enter for example 15,21 in textbox1 and enter 15 in textbox2 and put brakpoint on the line i commented below,and i understood that it doesnt put the number in textbox2 in searchnums(commented),for more explanation i comment in code.thanks in advance public void button1_Click(object sender, EventArgs e) { int searchnums = Convert.ToInt32(textBox2.Text);//the problem is here,the value in textbox2 doesnt exist in searchnums and it has value 0. int result = binarysearch(searchnums); MessageBox.Show(result.ToString()); } public int binarysearch(int searchnum) { string[] source = textBox1.Text.Split(','); int[] nums = new int[source.Length]; for (int i = 0; i < source.Length; i++) { nums[i] = Convert.ToInt32(source[i]); } int first =0; int last = nums.Length; int mid = (int)Math.Floor(nums.Length / 2.0); while (1<= nums.Length) { if (searchnum < nums[mid]) { last = mid - 1; } if (searchnum > nums[mid]) { first = mid + 1; } else { return nums[mid]; } } return -1; }

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• Flag bit computation and detection

  - by Majid

  Hi all, In some code I'm working on I should take care of ten independent parameters which can take one of two values (0 or 1). This creates 2^10 distinct conditions. Some of the conditions never occur and can be left out, but those which do occur are still A LOT and making a switch to handle all cases is insane. I want to use 10 if statements instead of a huge switch. For this I know I should use flag bits, or rather flag bytes as the language is javascript and its easier to work with a 10 byte string with to represent a 10-bit binary. Now, my problem is, I don't know how to implement this. I have seen this used in APIs where multiple-selectable options are exposed with numbers 1, 2, 4, 8, ... , n^(n-1) which are decimal equivalents of 1, 10, 100, 1000, etc. in binary. So if we make call like bar = foo(7), bar will be an object with whatever options the three rightmost flags enable. I can convert the decimal number into binary and in each if statement check to see if the corresponding digit is set or not. But I wonder, is there a way to determine the n-th digit of a decimal number is zero or one in binary form, without actually doing the conversion?

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• Very slow guards in my monadic random implementation (haskell)

  - by danpriduha

  Hi! I was tried to write one random number generator implementation, based on number class. I also add there Monad and MonadPlus instance. What mean "MonadPlus" and why I add this instance? Because of I want to use guards like here: -- test.hs -- import RandomMonad import Control.Monad import System.Random x = Rand (randomR (1 ::Integer, 3)) ::Rand StdGen Integer y = do a <-x guard (a /=2) guard (a /=1) return a here comes RandomMonad.hs file contents: -- RandomMonad.hs -- module RandomMonad where import Control.Monad import System.Random import Data.List data RandomGen g => Rand g a = Rand (g ->(a,g)) | RandZero instance (Show g, RandomGen g) => Monad (Rand g) where return x = Rand (\g ->(x,g)) (RandZero)>>= _ = RandZero (Rand argTransformer)>>=(parametricRandom) = Rand funTransformer where funTransformer g | isZero x = funTransformer g1 | otherwise = (getRandom x g1,getGen x g1) where x = parametricRandom val (val,g1) = argTransformer g isZero RandZero = True isZero _ = False instance (Show g, RandomGen g) => MonadPlus (Rand g) where mzero = RandZero RandZero `mplus` x = x x `mplus` RandZero = x x `mplus` y = x getRandom :: RandomGen g => Rand g a ->g ->a getRandom (Rand f) g = (fst (f g)) getGen :: RandomGen g => Rand g a ->g -> g getGen (Rand f) g = snd (f g) when I run ghci interpreter, and give following command getRandom y (mkStdGen 2000000000) I can see memory overflow on my computer (1G). It's not expected, and if I delete one guard, it works very fast. Why in this case it works too slow? What I do wrong?

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• Count bits used in int

  - by sigvardsen

  If you have the binary number 10110 how can I get it to return 5? e.g a number that tells how many bits are used? There are some likewise examples listed below: 101 should return 3 000000011 should return 2 11100 should return 5 101010101 should return 9 How can this be obtained the easiest way in Java? I have come up with the following method but can i be done faster: public static int getBitLength(int value) { int l = 1; if (value >> 16 > 0) { value = value >> 16; l += 16; } if (value >> 8 > 0) { value = value >> 8; l += 8; } if (value >> 4 > 0) { value = value >> 4; l += 4; } if (value >> 2 > 0) { value = value >> 2; l += 2; } if (value >> 1 > 0) { value = value >> 1; l += 1; } return l; }

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• KODO: how set up fetch plan for bidirectional relationships?

  - by BestPractices

  Running KODO 4.2 and having an issue inefficient queries being generated by KODO. This happens when fetching an object that contains a collection where that collection has a bidrectional relationship back to the first object. Class Classroom { List<Student> _students; } Class Student { Classroom _classroom; } If we create a fetch plan to get a list of Classrooms and their corresponding Students by setting up the following fetch plan: fetchPlan.addField(Classroom.class,”_students”); This will result in two queries (get the classrooms and then get all students that are in those classrooms), which is what we would expect. However, if we include the reference back to the classroom in our fetch plan in order for the _classroom field to get populated by doing fetchPlan.addField(Student.class, “_classroom”), this will result in X number of additional queries where X is the number of students in each classroom. Can anyone explain how to fix this? KODO already has the original Classroom objects at the point that it's executing the queries to retrieve the Classroom objects and set them in each Student object's _classroom field. So I would expect KODO to simply set those objects in the _classroom field on each Student object accordingly and not go back to the database. Once again, the documentation is sorely lacking with Kodo/JDO/OpenJPA but from what I've read it should be able to do this more efficiently. Note-- EAGER_FETCH.PARALLEL is turned on and I have tried this with caching (query and data caches) turned on and off and there is no difference in the resultant queries.

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• Newsletter send using AJAX to avoid PHP timeout

  - by simPod

  I need to send newsletters. I have already a PHP script that sends mass emails but it won't work for long as email database is growing because of PHP max script run time. So, to avoid it I came up with a solution: I would call my PHP script using AJAX in javascript and I will give it $_GET parameter with a count 20 so the script would sent only 20 emails. Than AJAX would receive success response, and call my script again and again till all emails are send. Is it possible? I'm asking because I have never seen such a solution so I'm wondering if it is real (It's kinda hard to implement this into my PHP framework so I'm asking experts here first) To sum it up here's a code skeleton: <script> var emailCount = 1000; //would get this from DB var runCount = 20; //number of emails sent in one cycle var from = 0; //start number function sendMail(){ if(from<emailCount){ jQuery.ajaxfunction({ path: 'script.php?from='+from+'&count='+runCount successFc: function(){ from+=runCount; sendMail(); } }) } } sendMail(); </script> So, are there any obstacles? Thanks a lot.

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• Calculate the retrieved rows in database Visual C#

  - by Tanya Lertwichaiworawit

  I am new in Visual C# and would want to know how to calculate the retrieved data from a database. Using the above GUI, when "Calculate" is click, the program will display the number of students in textBox1, and the average GPA of all students in textBox2. Here is my database table "Students": I was able to display the number of students but I'm still confused to how I can calculate the average GPA Here's my code: private void button1_Click(object sender, EventArgs e) { string connection = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Database1.accdb"; OleDbConnection connect = new OleDbConnection(connection); string sql = "SELECT * FROM Students"; connect.Open(); OleDbCommand command = new OleDbCommand(sql, connect); DataSet data = new DataSet(); OleDbDataAdapter adapter = new OleDbDataAdapter(command); adapter.Fill(data, "Students"); textBox1.Text = data.Tables["Students"].Rows.Count.ToString(); double gpa; for (int i = 0; i < data.Tables["Students"].Rows.Count; i++) { gpa = Convert.ToDouble(data.Tables["Students"].Rows[i][2]); } connect.Close(); }

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• Is there a way to increase performance on my simple textfilter?

  - by djerry

  Hey guys, I'm writing a filter that will pick out items. I have a list of Objects. The objects contain a number, name and some other irrelevant items. At the moment, the list contains 200 items. When typing in a textbox, i'm looking if the string matches a part of the number/name of the objects in the list. If so, add them to the listbox. Here's the code for my textbox textchanged event : private void txtTelnumber_TextChanged(object sender, TextChangedEventArgs e) { lstOverview.Items.Clear(); string data = ""; foreach (ucTelListItem telList in _allUsers) { data = telList.User.H323 + telList.user.E164; if (data.Contains(txtTelnumber.Text)) lstOverview.Items.Add(telList); } } I sometimes see a little delay when entering a character, especially when i go from 4 records to 200 records (so when i had a filter and 4 records matched, and i backspace and the whole list appears again). My list is a list of usercontrols, cause i found it takes less time to load the usercontrols from a list, then to have to initialize a new usercontrol each time. Can i do something about the code, or is it just adding the usercontrol the listbox that causes the small delay (small delay = <1 sec)? Thanks in advance.

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• CEIL is one too high for exact integer divisions

  - by Synetech

  This morning I lost a bunch of files, but because the volume they were one was both internally and externally defragmented, all of the information necessary for a 100% recovery is available; I just need to fill in the FAT where required. I wrote a program to do this and tested it on a copy of the FAT that I dumped to a file and it works perfectly except that for a few of the files (17 out of 526), the FAT chain is one single cluster too long, and thus cross-linked with the next file. Fortunately I know exactly what the problem is. I used ceil in my EOF calculation because even a single byte over will require a whole extra cluster: //Cluster is the starting cluster of the file //Size is the size (in bytes) of the file //BPC is the number of bytes per cluster //NumClust is the number of clusters in the file //EOF is the last cluster of the file’s FAT chain DWORD NumClust = ceil( (float)(Size / BPC) ) DWORD EOF = Cluster + NumClust; This algorithm works fine for everything except files whose size happens to be exactly a multiple of the cluster size, in which case they end up being one cluster too much. I thought about it for a while but am at a loss as to a way to do this. It seems like it should be simple but somehow it is surprisingly tricky. What formula would work for files of any size?

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• Better way to summarize data about stop times?

  - by Vimvq1987

  This question is close to this: http://stackoverflow.com/questions/2947963/find-the-period-of-over-speed Here's my table: Longtitude Latitude Velocity Time 102 401 40 2010-06-01 10:22:34.000 103 403 50 2010-06-01 10:40:00.000 104 405 0 2010-06-01 11:00:03.000 104 405 0 2010-06-01 11:10:05.000 105 406 35 2010-06-01 11:15:30.000 106 403 60 2010-06-01 11:20:00.000 108 404 70 2010-06-01 11:30:05.000 109 405 0 2010-06-01 11:35:00.000 109 405 0 2010-06-01 11:40:00.000 105 407 40 2010-06-01 11:50:00.000 104 406 30 2010-06-01 12:00:00.000 101 409 50 2010-06-01 12:05:30.000 104 405 0 2010-06-01 11:05:30.000 I want to summarize times when vehicle had stopped (velocity = 0), include: it had stopped since "when" to "when" in how much minutes, how many times it stopped and how much time it stopped. I wrote this query to do it: select longtitude, latitude, MIN(time), MAX(time), DATEDIFF(minute, MIN(Time), MAX(time)) as Timespan from table_1 where velocity = 0 group by longtitude,latitude select DATEDIFF(minute, MIN(Time), MAX(time)) as minute into #temp3 from table_1 where velocity = 0 group by longtitude,latitude select COUNT(*) as [number]from #temp select SUM(minute) as [totaltime] from #temp3 drop table #temp This query return: longtitude latitude (No column name) (No column name) Timespan 104 405 2010-06-01 11:00:03.000 2010-06-01 11:10:05.000 10 109 405 2010-06-01 11:35:00.000 2010-06-01 11:40:00.000 5 number 2 totaltime 15 You can see, it works fine, but I really don't like the #temp table. Is there anyway to query this without use a temp table? Thank you.

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• Every flash uploader giving bad progress values.

  - by Mike Boers

  The file upload script I wrote early last year for an internal website has been misbehaving oddly on a number of machines. On some machines it consistently works fine, on others it consistently misbehaves. I am having exactly the same problem with YUI Uploader, SWFUpload (2.2 and 2.5a), and Uploadify. On the misbehaving machines, the progress event (or callback as the case may be) is reporting the upload going far too quickly. It is progressing around 9 or 10MB/s, instead of the 50 or 60kb/s that is actually going on. The progress bar fills up very quickly, and then no more progress events are triggered. A few minutes later the completion event will trigger when the upload is actually done. I must emphasize that the file upload does proceed normally, even though the progress being reported is very wrong. The progress events are reporting a correct file size, but the reported amount uploaded is usually way too high, and it appears that it is always a multiple of 2^16 (65536). I'm only having this problem with Firefox 3.5 on Windows XP, all of which have various subversions of Flash 10. Has anyone heard of this happening, or have any idea what is going on? (I'm off to go file a number of bug reports, but hopefully someone here has some previous experience with this.)

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• Growing user control not updating

  - by user328259

  I am developing in C# and .Net 2.0. I have a user control that draws cells (columnar) depending upon the maximum number of cells. There are some drawing routines that generate the necessary cells. There is a property NumberOfCells that adjust the height of this control; CELLHEIGHT_CONSTANT * NumberOfCells. The OnPaint() method is overridden (code that draws the Number of cells). There is another user control that contains a panel which contains the userControl1 from above. There is a property NumberCells that changes userControl1's NumberOfCells. UserControl2 is then placed on a windows form. On that form there is a NumericUpDown control (only increments from 1). When the user increments by 1, I adjust the VerticalScroll.Maximum by 1 as well. Everything works well and good BUT when I increment once, the panel updates fine (inserts a vertical scrolll when necessary) but cells are not being added! I've tried Invalidating on userControl2 AND on the form but nothing seems to draw the newly added cells. Any assistance is appreciated. Thank you in advance. Lawrence

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• Algorithm for count-down timer that can add on time

  - by Person

  I'm making a general timer that has functionality to count up from 0 or count down from a certain number. I also want it to allow the user to add and subtract time. Everything is simple to implement except for the case in which the timer is counting down from some number, and the user adds or subtracts time from it. For example: (m_clock is an instance of SFML's Clock) float Timer::GetElapsedTime() { if ( m_forward ) { m_elapsedTime += m_clock.GetElapsedTime() - m_elapsedTime; } else { m_elapsedTime -= m_elapsedTime - m_startingTime + m_clock.GetElapsedTime(); } return m_elapsedTime; } To be a bit more clear, imagine that the timer starts at 100 counting down. After 10 seconds, the above function would look like 100 -= 100 - 100 + 10 which equals 90. If it was called after 20 more seconds it would look like 90 -= 90 - 100 + 30 which equals 70. This works for normal counting, but if the user calls AddTime() ( just m_elapsedTime += arg ) then the algorithm for backwards counting fails miserably. I know that I can do this using more members and keeping track of previous times, etc. but I'm wondering whether I'm missing some implementation that is extremely obvious. I'd prefer to keep it as simple as possible in that single operation.

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• Unit testing with Mocks. Test behaviour not implementation

  - by Kenny Eliasson

  Hi.. I always had a problem when unit testing classes that calls other classes, for example I have a class that creates a new user from a phone-number then saves it to the database and sends a SMS to the number provided. Like the code provided below. public class UserRegistrationProcess : IUserRegistration { private readonly IRepository _repository; private readonly ISmsService _smsService; public UserRegistrationProcess(IRepository repository, ISmsService smsService) { _repository = repository; _smsService = smsService; } public void Register(string phone) { var user = new User(phone); _repository.Save(user); _smsService.Send(phone, "Welcome", "Message!"); } } It is a really simple class but how would you go about and test it? At the moment im using Mocks but I dont really like it [Test] public void WhenRegistreringANewUser_TheNewUserIsSavedToTheDatabase() { var repository = new Mock<IRepository>(); var smsService = new Mock<ISmsService>(); var userRegistration = new UserRegistrationProcess(repository.Object, smsService.Object); var phone = "0768524440"; userRegistration.Register(phone); repository.Verify(x => x.Save(It.Is<User>(user => user.Phone == phone)), Times.Once()); } [Test] public void WhenRegistreringANewUser_ItWillSendANewSms() { var repository = new Mock<IRepository>(); var smsService = new Mock<ISmsService>(); var userRegistration = new UserRegistrationProcess(repository.Object, smsService.Object); var phone = "0768524440"; userRegistration.Register(phone); smsService.Verify(x => x.Send(phone, It.IsAny<string>(), It.IsAny<string>()), Times.Once()); } It feels like I am testing the wrong thing here? Any thoughts on how to make this better?

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• How to Declare Complex Nested C# Type for Web Service

  - by TheArtTrooper

  I would like to create a service that accepts a complex nested type. In a sample asmx file I created: [WebService(Namespace = "http://tempuri.org/")] [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] // To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. // [System.Web.Script.Services.ScriptService] public class ServiceNest : System.Web.Services.WebService { public class Block { [XmlElement(IsNullable = false)] public int number; } public class Cell { [XmlElement(IsNullable = false)] public Block block; } public class Head { [XmlElement(IsNullable = false)] public Cell cell; } public class Nest { public Head head; } [WebMethod] public void TakeNest(Nest nest) { } } When I view the asmx file in IE the test page shows the example SOAP post request as: <?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <soap:Body> <TakeNest xmlns="http://schemas.intellicorp.com/livecompare/"> <nest> <head> <cell> <block xsi:nil="true" /> </cell> </head> </nest> </TakeNest> </soap:Body> </soap:Envelope> It hasn't expanded the <block> into its number member. Looking at the WSDL, the types all look good. So is this just a limitation of the post demo page creator? Thanks.

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• How do I create efficient instance variable mutators in Matlab?

  - by Trent B

  Previously, I implemented mutators as follows, however it ran spectacularly slowly on a recursive OO algorithm I'm working on, and I suspected it may have been because I was duplicating objects on every function call... is this correct? %% Example Only obj2 = tripleAllPoints(obj1) obj.pts = obj.pts * 3; obj2 = obj1 end I then tried implementing mutators without using the output object... however, it appears that in MATLAB i can't do this - the changes won't "stick" because of a scope issue? %% Example Only tripleAllPoints(obj1) obj1.pts = obj1.pts * 3; end For application purposes, an extremely simplified version of my code (which uses OO and recursion) is below. classdef myslice properties pts % array of pts nROW % number of rows nDIM % number of dimensions subs % sub-slices end % end properties methods function calcSubs(obj) obj.subs = cell(1,obj.nROW); for i=1:obj.nROW obj.subs{i} = myslice; obj.subs{i}.pts = obj.pts(1:i,2:end); end end function vol = calcVol(obj) if obj.nROW == 1 obj.volume = prod(obj.pts); else obj.volume = 0; calcSubs(obj); for i=1:obj.nROW obj.volume = obj.volume + calcVol(obj.subs{i}); end end end end % end methods end % end classdef

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• Dynamically generate client-side HTML form control using JavaScript and server-side Python code in Google App Engine

  - by gisc

  I have the following client-side front-end HTML using Jinja2 template engine: {% for record in result %} <textarea name="remark">{{ record.remark }}</textarea> <input type="submit" name="approve" value="Approve" /> {% endfor %} Thus the HTML may show more than 1 set of textarea and submit button. The back-end Python code retrieves a variable number of records from a gql query using the model, and pass this to the Jinja2 template in result. When a submit button is clicked, it triggers the post method to update the record: def post(self): if self.request.get('approve'): updated_remark = self.request.get('remark') record.remark = db.Text(updated_remark) record.put() However, in some instances, the record updated is NOT the one that correspond to the submit button clicked (eg if a user clicks on record 1 submit, record 2 remark gets updated, but not record 1). I gather that this is due to the duplicate attribute name remark. I can possibly use JavaScript/jQuery to generate different attribute names. The question is, how do I code the back-end Python to get the (variable number of) names generated by the JavaScript? Thanks.

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• Drawing an honeycomb with as3

  - by vitto

  Hi, I'm trying to create an honeycomb with as3 but I have some problem on cells positioning. I've already created the cells (not with code) and for cycled them to a funcion and send to it the parameters which what I thought was need (the honeycomb cell is allready on a sprite container in the center of the stage). to see the structure of the cycle and which parameters passes, please see the example below, the only thing i calculate in placeCell is the angle which I should obtain directly inside tha called function Note: the angle is reversed but it isn't important, and the color are useful in example only for visually divide cases. My for cycle calls placeCell and passes cell, current_case, counter (index) and the honeycomb cell_lv (cell level). I thought it was what i needed but I'm not skilled in geometry and trigonometry, so I don't know how to position cells correctly: function placeCell (cell:Sprite, current_case:int, counter:int, cell_lv:int):void { var margin:int = 2; var angle:Number = (360 / (cell_lv * 6)) * (current_case + counter); var radius:Number = (cell.width + margin) * cell_lv; cell.x = radius * Math.cos (angle); cell.y = radius * Math.sin (angle); trace ("LV " + cell_lv + " current_case " + current_case + " counter " + counter + " angle " + angle + " radius " + radius) } how can I do to solve it?

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• Pairs from single list

  - by Apalala

  Often enough, I've found the need to process a list by pairs. I was wondering which would be the pythonic and efficient way to do it, and found this on Google: pairs = zip(t[::2], t[1::2]) I thought that was pythonic enough, but after a recent discussion involving idioms versus efficiency, I decided to do some tests: import time from itertools import islice, izip def pairs_1(t): return zip(t[::2], t[1::2]) def pairs_2(t): return izip(t[::2], t[1::2]) def pairs_3(t): return izip(islice(t,None,None,2), islice(t,1,None,2)) A = range(10000) B = xrange(len(A)) def pairs_4(t): # ignore value of t! t = B return izip(islice(t,None,None,2), islice(t,1,None,2)) for f in pairs_1, pairs_2, pairs_3, pairs_4: # time the pairing s = time.time() for i in range(1000): p = f(A) t1 = time.time() - s # time using the pairs s = time.time() for i in range(1000): p = f(A) for a, b in p: pass t2 = time.time() - s print t1, t2, t2-t1 These were the results on my computer: 1.48668909073 2.63187503815 1.14518594742 0.105381965637 1.35109519958 1.24571323395 0.00257992744446 1.46182489395 1.45924496651 0.00251388549805 1.70076990128 1.69825601578 If I'm interpreting them correctly, that should mean that the implementation of lists, list indexing, and list slicing in Python is very efficient. It's a result both comforting and unexpected. Is there another, "better" way of traversing a list in pairs? Note that if the list has an odd number of elements then the last one will not be in any of the pairs. Which would be the right way to ensure that all elements are included? I added these two suggestions from the answers to the tests: def pairwise(t): it = iter(t) return izip(it, it) def chunkwise(t, size=2): it = iter(t) return izip(*[it]*size) These are the results: 0.00159502029419 1.25745987892 1.25586485863 0.00222492218018 1.23795199394 1.23572707176 Results so far Most pythonic and very efficient: pairs = izip(t[::2], t[1::2]) Most efficient and very pythonic: pairs = izip(*[iter(t)]*2) It took me a moment to grok that the first answer uses two iterators while the second uses a single one. To deal with sequences with an odd number of elements, the suggestion has been to augment the original sequence adding one element (None) that gets paired with the previous last element, something that can be achieved with itertools.izip_longest().

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• Generic callbacks

  - by bobobobo

  Extends So, I'm trying to learn template metaprogramming better and I figure this is a good exercise for it. I'm trying to write code that can callback a function with any number of arguments I like passed to it. // First function to call int add( int x, int y ) ; // Second function to call double square( double x ) ; // Third func to call void go() ; The callback creation code should look like: // Write a callback object that // will be executed after 42ms for "add" Callback<int, int, int> c1 ; c1.func = add ; c1.args.push_back( 2 ); // these are the 2 args c1.args.push_back( 5 ); // to pass to the "add" function // when it is called Callback<double, double> c2 ; c2.func = square ; c2.args.push_back( 52.2 ) ; What I'm thinking is, using template metaprogramming I want to be able to declare callbacks like, write a struct like this (please keep in mind this is VERY PSEUDOcode) <TEMPLATING ACTION <<ANY NUMBER OF TYPES GO HERE>> > struct Callback { double execTime ; // when to execute TYPE1 (*func)( TYPE2 a, TYPE3 b ) ; void* argList ; // a stored list of arguments // to plug in when it is time to call __func__ } ; So for when called with Callback<int, int, int> c1 ; You would automatically get constructed for you by < HARDCORE TEMPLATING ACTION > a struct like struct Callback { double execTime ; // when to execute int (*func)( int a, int b ) ; void* argList ; // this would still be void*, // but I somehow need to remember // the types of the args.. } ; Any pointers in the right direction to get started on writing this?

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