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  • Evolutionary Algorithms: Optimal Repopulation Breakdowns

    - by Brian MacKay
    It's really all in the title, but here's a breakdown for anyone who is interested in Evolutionary Algorithms: In an EA, the basic premise is that you randomly generate a certain number of organisms (which are really just sets of parameters), run them against a problem, and then let the top performers survive. You then repopulate with a combination of crossbreeds of the survivors, mutations of the survivors, and also a certain number of new random organisms. Do that several thousand times, and efficient organisms arise. Some people also do things like introduce multiple "islands" of organisms, which are seperate populations that are allowed to crossbreed once in awhile. So, my question is: what are the optimal repopulation percentages? I have been keeping the top 10% performers, and repopulating with 30% crossbreeds and 30% mutations. The remaining 30% is for new organisms. I have also tried out the multiple island theory, and I'm interested in your results on that as well. It is not lost on me that this is exactly the type of problem an EA could solve. Are you aware of anyone trying that? Thanks in advance!

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  • Best open source Mixed Integer Optimization Solver

    - by Mark
    I am using CPLEX for solving huge optimization models (more than 100k variables) now I'd like to see if I can find an open source alternative, I solve mixed integer problems (MILP) and CPLEX works great but it is very expensive if we want to scale so I really need to find an alternative or start writing our own ad-hoc optimization library (which will be painful) Any suggestion/insight would be much appreciated

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  • Efficient Map Overlays in on Android Google Map...

    - by Ahsan
    Hi Friends, I want to do the following and am kind of stuck on these for a few days.... 1) I have used helloItemizedOverlay to add about 150 markers and it gets very very slow.....any idea what to do ? I was thinking about threads....(handler) ... 2) I was trying to draw poly lines ( I have encoded polylines, but have managed to decoded those) that move when I move the map.....(the only solution that I found was for Geopoints to be transformed into screen co-ordinates...which wont move if I move the map !) 3) I was looking for some sort of a timer function that executes a given function, say, every 1 minute or so.... 4) I was also looking for ways to clear the Google map from all the markers/lines etc.... Thanks a lot... :) - ahsan

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  • Python: unix socket -> broken pipe

    - by Heinrich Schmetterling
    I'm trying to get Python socket working as an alternative to calling the command line socat. This socat command works fine: echo 'cmd' | sudo socat stdio <path-to-socket> but when I run this python code, I get an error: >>> import socket >>> s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) >>> s.connect(<path-to-socket>) >>> s.send('cmd') Traceback (most recent call last): File "<stdin>", line 1, in <module> socket.error: (32, 'Broken pipe') Any ideas what the issue is? Thanks.

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  • Why doesn't Python require exactly four spaces per indentation level?

    - by knorv
    Whitespace is signification in Python in that code blocks are defined by their indentation. Furthermore, Guido van Rossum recommends using four spaces per indentation level (see PEP 8: Style Guide for Python Code). What was the reasoning behind not requiring exactly four spaces per indentation level as well? Are there any technical reasons? It seems like all the arguments that can be made for making whitespace define code blocks can also be used to argument for setting an exact whitespace length for one indentation level (say four spaces).

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  • The advantages and disadvantages of using ORM

    - by JHarley1
    Good Morning, I would like to discuss today the advantages and disadvantages of using ORM (such as ADO.NET). Advantages: Speeds-up Development - eliminates the need for repetitive SQL code. Reduces Development Time. Reduces Development Costs. Overcomes vendor specific SQL differences - the ORM knows how to write vendor specific SQL so you don't have to. Disadvantages: Loss in developer productivity whilst they learn to program with ORM. Developers loose understanding of what the code is actually doing - the developer is more in control using SQL. ORM has a tendency to be slow. ORM fail to compete against SQL queries for complex queries. In summary, I believe that the disadvantages of using an ORM (mainly the reduced time taken to perform repetitive tasks) is far outweighed by the disadvantages of ORM e.g. its difficulty to get to grips with. Can people point out were I am going wrong and suggest any further advantages/disadvantages. Many Thanks, J

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  • shell script output in html + email that html

    - by Kimi
    Using Solaris I have a monitoring script that uses other scripts as plugins. Theses pugins are also scripts which work in difffernt ways like: 1. Sending an alert while high memory uilization 2. High Cpu usage 3. Full disk Space 4. chekcking the core file dump Now all this is dispalyed on my terminal and I want to put them in a HTML file/format and send it as a body of the mail not as attachment. Thanks .

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  • Data Collection (Offline - no internet) and then syncing it to generate reports from server

    - by Nishant
    So, I have a new project I am planning on taking, and needed to know what skills will be required to achieve this project. The project is to do intensive data collection in the field where they don't have internet access. As part of the data collection, images will be uploaded as part of the data collection which will have to be resized, etc. Once the data collection occurs, this data needs to be consolidated and reported on. I am thinking there are two ways of generating the report. 1. Into a PDF that can be designed. 2. Is there a way to generate an executable file (since the PDF will be huge due to multiple images, etc) and the executable file is navigation friendly with drop-downs etc. It might not be an executable file, but could be a web page or some way that this can be delivered to the client in a friendly professional way. The PDF will have to be generated somehow so that it can be printed as a hard copy. What languages and skill sets will I need to accomplish this project?

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  • Function syntax puzzler in scalaz

    - by oxbow_lakes
    Following watching Nick Partidge's presentation on deriving scalaz, I got to looking at this example, which is just awesome: import scalaz._ import Scalaz._ def even(x: Int) : Validation[NonEmptyList[String], Int] = if (x % 2 ==0) x.success else "not even: %d".format(x).wrapNel.fail println( even(3) <|*|> even(5) ) //prints: Failure(NonEmptyList(not even: 3, not even: 5)) I was trying to understand what the <|*|> method was doing, here is the source code: def <|*|>[B](b: M[B])(implicit t: Functor[M], a: Apply[M]): M[(A, B)] = <**>(b, (_: A, _: B)) OK, that is fairly confusing (!) - but it references the <**> method, which is declared thus: def <**>[B, C](b: M[B], z: (A, B) => C)(implicit t: Functor[M], a: Apply[M]): M[C] = a(t.fmap(value, z.curried), b) So I have a few questions: How come the method appears to take a monad of one type parameter (M[B]) but can get passed a Validation (which has two type paremeters)? How does the syntax (_: A, _: B) define the function (A, B) => C which the 2nd method expects? It doesn't even define an output via =>

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  • Self Assessment Tests for Programmers

    - by THX1138.6
    I want to help the Dev team identify areas of knowledge (practical and theoretical) that they can work on. Though I am big believer in focusing on people's strengths being a good programmer requires (I think) being challenged by concepts and ideas that don't always come naturally. We work largely in the web app space using PHP & MySQL but better skills in data modelling, query optimisation, use of MVC and OOP etc. would help the team and the company a lot. I want to help the Dev team manage their careers, explore and expand their skills sets. Be all they can be and better than they were previously. I know its an idealistic goal but work must be about more than simply getting the work done. There should be some time to review, to learn, to grow and get better. Any thoughts, ideas, opinions and directions to tests or similar resources would be greatly appreciated.

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  • Setting article properties for a publication using RMO in C# .NET

    - by Pavan Kumar
    I am using transaction replication with push subscription. I am developing a UI for replication using RMO in C#.NET between different instances of the same database within same machine holding similar schema and structure. I am using Single subscriber and multiple publisher topology. During creation of publication i want to set a few article properties such as Keep the existing object unchanged ,allow schema changes at subscriber to false a,copy foriegn key constarint and copy check constraints to true. How do i set the article properties using RMO in C# .NET. I am using Visual Studio 2008 SP1.I also want to know as how we can select all the objects including Tables,Views,Stored Procedures for publishing at one stretch. I could do it for one table but i want to select all the tables at one stretch. This is the code snippet i used for selecting single table for publishing. TransArticle ta = new TransArticle(); ta.Name = "Article_1"; ta.PublicationName = "TransReplication_DB2"; ta.DatabaseName = "DB2"; ta.SourceObjectName = "person"; ta.SourceObjectOwner = "dbo"; ta.ConnectionContext = conn; ta.Create();

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  • Dynamics of the using keyword

    - by AngryHacker
    Consider the following code: // module level declaration Socket _client; void ProcessSocket() { _client = GetSocketFromSomewhere(); using (_client) { DoStuff(); // receive and send data Close(); } } void Close() { _client.Close(); _client = null; } Given that that the code calls the Close() method, which closes the _client socket and sets it to null, while still inside the `using' block, what exactly happens behind the scenes? Does the socket really get closed? Are there side effects? P.S. This is using C# 3.0 on the .NET MicroFramework, but I suppose the c#, the language, should function identically. The reason i am asking is that occasionally, very rarely, I run out of sockets (which is a very precious resource on a .NET MF devices).

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  • FireLog: proper installation...

    - by kent
    I have installed the firewiresdk26 on my dev mac... and in the Tools/ directory is FireLog. I have run the FireLog 2.0.0.pkg installer on my dev mac, but the payload it deploys is installed in my /System/Library tree, as opposed to my /Developer/SDKs tree. so when I try to include the header iokit/firewire/FireLog.h it does not get found. am I missing something? or doing something wrong? or is this an error in the installer (either FW26 or FireLog installers?) I realize that the FireLog installer is intended to be run on the machine to be debugged remotely and thus it makes sense that the framework is placed in the /System/Library path, however none of the installers gets it into my developer path... I guess I just have to move it over there by hand, but before I do that I wanted to see if I'm just overlooking something silly and need to read the docs with more concentration or something... anyone run into this before? [thx]

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  • Can immutable be a memory hog?

    - by ciscoheat
    Let's say we have a memory-intensive class like an Image, with chainable methods like Resize() and ConvertTo(). If this class is immutable, won't it take a huge amount of memory when I start doing things like i.Resize(500, 800).Rotate(90).ConvertTo(Gif), compared to a mutable one which modifies itself? How to handle a situation like this in a functional language?

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  • How to get Acknowlegement in TCP communication in Java

    - by Sunil Kumar Sahoo
    I have written a socket program in Java. Both server and client can sent/receive data to each other. But I found that if client sends data to server using TCP then internally TCP sends acknowledgement to the client once the data is received by the server. I want to detect or handle that acknowledgement. How can I read or write data in TCP so that I can handle TCP acknowledgement. Thanks Sunil Kumar Sahoo

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  • Able to ping but cannot browse after several hours running of my python program

    - by Shane
    It's a GUI program I wrote in python checking website/server status running on my XP SP3, multi threads are used to check different site/server. After several hours running, the program starts to get urlopen error timed out all the time, and this always happens right after a POST request from a server(not a certain one, might be A or B or C), and it's also not the first POST request causing the problem, normally after several hours running and it happens to make a POST request at an unknown moment, all you get from then on is urlopen error timed out. I'm still able to ping but cannot browse any site, once the program closed everything's fine. It's definitely the program causing this problem, well I just don't know how to debug/check what the problem is, also don't know if it's from OS side or my program wasting too many resources/connections(are you still able to ping when too many connections used?), would anybody please help me out?

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  • TcpListener.Start() does not open the port

    - by SoMoS
    Hello, I have a class that inherits from the TcpListener, this class Shadows the Start method just to call the base Start() and the base BeginAcceptTcpClient(). From time to time the method is called but the port is not opened (netstat does not show the port open). The class looks like this Public Class ExtendedTcpListener Inherits System.Net.Sockets.TcpListener Public Shadows Sub Start() SyncLock (m_stopLock) MyBase.Start() MyBase.BeginAcceptTcpClient(AddressOf Me.CompleteAcceptTcpClient, Me) My.Application.Log.WriteEntry("Extended Tcp Listener started ...", TraceEventType.Verbose) End SyncLock End Sub Any idea on what's happening or how to debug the issue? As the Start() is called without exception I expected to find the port always opened (the log is always written). Extra information: when the Start method works fine it works each time until app is restarted. When the Start method does not work it won't work again until the app is restarted.

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  • JVM/CLR Source-compatible Language Options

    - by Nathan Voxland
    I have an open source Java database migration tool (http://www.liquibase.org) which I am considering porting to .Net. The majority of the tool (at least from a complexity side) is around logic like "if you are adding a primary key and the database is Oracle use this SQL. If database is MySQL use this SQL. If the primary key is named and the database is Postgres use this SQL". I could fork the Java codebase and covert it (manually and/or automatically), but as updates and bug fixes to the above logic come in I do not want to have to apply it to both versions. What I would like to do is move all that logic into a form that can be compiled and used by both Java and .Net versions naively. The code I am looking to convert does not contain any advanced library usage (JDBC, System.out, etc) that would vary significantly from Java to .Net, so I don't think that will be an issue (at worst it can be designed around). So what I am looking for is: A language in which I can code common parts of my app in and compile it into classes usable by the "standard" languages on the target platform Does not add any runtime requirements to the system Nothing so strange that it scares away potential contributors I know Python and Ruby both have implementations on for the JVM and CLR. How well do they fit my requirements? Has anyone been successful (or unsuccesful) using this technique for cross-platform applications? Are there any gotcha's I need to worry about?

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