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• Query MySQL data from Excel (or vice-versa)

  - by Charles

  I'm trying to automate a tedious problem. I get large Excel (.xls or .csv, whatever's more convenient) files with lists of people. I want to compare these against my MySQL database.* At the moment I'm exporting MySQL tables and reading them from an Excel spreadsheet. At that point it's not difficult to use =LOOKUP() and such commands to do the work I need, and of course the various text processing I need to do is easy enough to do in Excel. But I can't help but think that this is more work than it needs to be. Is there some way to get at the MySQL data directly from Excel? Alternately, is there a way I could access a reasonably large (~10k records) csv file in a sql script? This seems to be rather basic, but I haven't managed to make it work so far. I found an ODBC connection for MySQL but that doesn't seem to do what I need. In particular, I'm testing whether the name matches or whether any of four email addresses match. I also return information on what matched for the benefit of the next person to use the data, something like "Name 'Bob Smith' not found, but 'Robert Smith' matches on email address robert.smith@foo".

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• Why do my Sax Parser produce no results after using InputStream Read?

  - by Andy Barlow

  Hello, I have this piece of code which I'm hoping will be able to tell me how much data I have downloaded (and soon put it in a progress bar), and then parse the results through my Sax Parser. If I comment out basically everything above the //xr.parse(new InputSource(request.getInputStream())); line and swap the xr.parse's over, it works fine. But at the moment, my Sax parser tells me I have nothing. Is it something to do with is.read (buffer) section? Also, just as a note, request is a HttpURLConnection with various signatures. /*Input stream to read from our connection*/ InputStream is = request.getInputStream(); /*we make a 2 Kb buffer to accelerate the download, instead of reading the file a byte at once*/ byte [ ] buffer = new byte [ 2048 ] ; /*How many bytes do we have already downloaded*/ int totBytes,bytes,sumBytes = 0; totBytes = request.getContentLength () ; while ( true ) { /*How many bytes we got*/ bytes = is.read (buffer); /*If no more byte, we're done with the download*/ if ( bytes <= 0 ) break; sumBytes+= bytes; Log.v("XML", sumBytes + " of " + totBytes + " " + ( ( float ) sumBytes/ ( float ) totBytes ) *100 + "% done" ); } /* Parse the xml-data from our URL. */ // OLD, and works if comment all the above //xr.parse(new InputSource(request.getInputStream())); xr.parse(new InputSource(is)) /* Parsing has finished. */; Can anyone help me at all?? Kind regards, Andy

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• Why does adding Crossover to my Genetic Algorithm gives me worse results?

  - by MahlerFive

  I have implemented a Genetic Algorithm to solve the Traveling Salesman Problem (TSP). When I use only mutation, I find better solutions than when I add in crossover. I know that normal crossover methods do not work for TSP, so I implemented both the Ordered Crossover and the PMX Crossover methods, and both suffer from bad results. Here are the other parameters I'm using: Mutation: Single Swap Mutation or Inverted Subsequence Mutation (as described by Tiendil here) with mutation rates tested between 1% and 25%. Selection: Roulette Wheel Selection Fitness function: 1 / distance of tour Population size: Tested 100, 200, 500, I also run the GA 5 times so that I have a variety of starting populations. Stop Condition: 2500 generations With the same dataset of 26 points, I usually get results of about 500-600 distance using purely mutation with high mutation rates. When adding crossover my results are usually in the 800 distance range. The other confusing thing is that I have also implemented a very simple Hill-Climbing algorithm to solve the problem and when I run that 1000 times (faster than running the GA 5 times) I get results around 410-450 distance, and I would expect to get better results using a GA. Any ideas as to why my GA performing worse when I add crossover? And why is it performing much worse than a simple Hill-Climb algorithm which should get stuck on local maxima as it has no way of exploring once it finds a local max?

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• How to modify ASCII table in C ? [closed]

  - by drigoSkalWalker

  Like this: My ASCII Chart 0 1 2 3 4 5 6 7 8 9 A B C D E F 0 NUL SOH STX ETX EOT ENQ ACK BEL BS HT LF VT FF CR SO SI 1 DLE DC1 DC2 DC3 DC4 NAK SYN ETB CAN EM SUB ESC FS GS RS US 2 SP ! " # $ % & ' ( ) * + , - . / 3 0 1 2 3 4 5 6 7 8 9 : ; ? 4 @ A B C D E F G H I J K L M N O 5 P Q R S T U V W X Y Z [ \ ] ^ _ 6 ` a b c d e f g h i j k l m n o 7 p q r s t u v w x y z { | } ~ DEL I want to call a function, alter the ASCII sequence in this function and when it returns, the ASCII sequence back to the original. Thanks in advance! EDIT: What I want is it: I want to change the order of chars, for examble, A is 65, if I want to make A equal a 0? without to make a function to do it, for example, I could accomplish it with a function that compare an array of chars, and store it in another way with the correct value (the new table), but do it is too expensive, is there another way? thanks in advance again!

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• Threads, Sockets, and Designing Low-Latency, High Concurrency Servers

  - by lazyconfabulator

  I've been thinking a lot lately about low-latency, high concurrency servers. Specifically, http servers. http servers (fast ones, anyway) can serve thousands of users simultaneously, with very little latency. So how do they do it? As near as I can tell, they all use events. Cherokee and Lighttpd use libevent. Nginx uses it's own event library performing much the same function of libevent, that is, picking a platform optimal strategy for polling events (like kqueue on *bsd, epoll on linux, /dev/poll on Solaris, etc). They all also seem to employ a strategy of multiprocess or multithread once the connection is made - using worker threads to handle the more cpu intensive tasks while another thread continues to listen and handle connections (via events). This is the extent of my understanding and ability to grok the thousand line sources of these applications. What I really want are finer details about how this all works. In examples of using events I've seen (and written) the events are handling both input and output. To this end, do the workers employ some sort of input/output queue to the event handling thread? Or are these worker threads handling their own input and output? I imagine a fixed amount of worker threads are spawned, and connections are lined up and served on demand, but how does the event thread feed these connections to the workers? I've read about FIFO queues and circular buffers, but I've yet to see any implementations to work from. Are there any? Do any use compare-and-swap instructions to avoid locking or is locking less detrimental to event polling than I think? Or have I misread the design entirely? Ultimately, I'd like to take enough away to improve some of my own event-driven network services. Bonus points to anyone providing solid implementation details (especially for stuff like low-latency queues) in C, as that's the language my network services are written in.

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• string Comparison

  - by muhammad-aslam

  I want to compare two user input strings, but not able to do so... #include "stdafx.h" #include "iostream" #include "string" using namespace std; int _tmain(int argc, _TCHAR* argv0[]) { string my_string; string my_string2; cout<<"Enter string"<<endl; cin>>my_string; cout<<"Enter 2nd string"<<endl; cin>>my_string2; cout<<my_string<<" "<<my_string2; strcmp(my_string,my_string2); int result; result= strcmp(my_string,my_string2); cout<<result<<endl; return 0; } This error is appearing. Error 1 error C2664: 'strcmp' : cannot convert parameter 1 from 'std::string' to 'const char *' c:\users\asad\documents\visual studio 2008\projects\string\string\string.cpp 23 String

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• Toggling list image and expand all jquery accordion w/ unordered lists

  - by Evan

  I have a functioning jquery accordion using pure unordered lists. I'm trying to incorporate 2 pieces of functionality. Here is my functioning accordion code and a demo of it working. http://jsbin.com/itibi4/ Toggling Arrows. i'm tring to get the parent bullets to be a toggling arrow and point down when clicked while the child bullets stay as bullets instead of an arrow. Would I be able to get some help with this? .inactive { background-image:url("http://img547.imageshack.us/img547/4103/arrowp.gif"); background-position:4px -31px; background-repeat:no-repeat; cursor:pointer; padding-left:20px; padding-top:10px; } .active { background-image: url("http://img547.imageshack.us/img547/4103/arrowp.gif"); background-position: 4px 12px; background-repeat:no-repeat; font-weight:bold; } Expand All / Collapse All also, i'm trying to incorporate an expand all / collapse all functionality. this is code to the same demo the code is from a previous project, which i've added below the unordered list menu, but i'm having difficulty incorporating it into this project. Would I be able to get some help with this? $('.swap').click(function() { if($(this).text() == 'Click to Collapse All FAQs') { $('ul.menu').slideUp('normal'); $('ul.menu li a').removeClass('active'); $(this).text($(this).text() == 'Click to Expand All FAQs' ? 'Click to Collapse All FAQs' : 'Click to Expand All FAQs'); } else { $('ul.menu').slideDown('normal'); $('ul.menu li a').addClass('active'); $(this).text($(this).text() == 'Click to Expand All FAQs' ? 'Click to Collapse All FAQs' : 'Click to Expand All FAQs'); } } Thank you so much for your help! Evan

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• Textually diffing JSON

  - by Richard Levasseur

  As part of my release processes, I have to compare some JSON configuration data used by my application. As a first attempt, I just pretty-printed the JSON and diff'ed them (using kdiff3 or just diff). As that data has grown, however, kdiff3 confuses different parts in the output, making additions look like giant modifies, odd deletions, etc. It makes it really hard to figure out what is different. I've tried other diff tools, too (meld, kompare, diff, a few others), but they all have the same problem. Despite my best efforts, I can't seem to format the JSON in a way that the diff tools can understand. Example data: [ { "name": "date", "type": "date", "nullable": true, "state": "enabled" }, { "name": "owner", "type": "string", "nullable": false, "state": "enabled", } ...lots more... ] The above probably wouldn't cause the problem (the problem occurs when there begin to be hundreds of lines), but thats the gist of what is being compared. Thats just a sample; the full objects are 4-5 attributes, and some attributes have 4-5 attributes in them. The attribute names are pretty uniform, but their values pretty varied. In general, it seems like all the diff tools confuse the closing "}" with the next objects closing "}". I can't seem to break them of this habit. I've tried adding whitespace, changing indentation, and adding some "BEGIN" and "END" strings before and after the respective objects, but the tool still get confused.

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• CMBufferQueueCreate fail, required parameters?

  - by Agustin

  Reading the documentation about iOS SDK CMBufferQueueCreate, it says that getDuration and version are required, all the others callbacks can be NULL. but running the following code: CFAllocatorRef allocator; CMBufferCallbacks *callbacks; callbacks = malloc(sizeof(CMBufferCallbacks)); callbacks->version = 0; callbacks->getDuration = timeCallback; callbacks->refcon = NULL; callbacks->getDecodeTimeStamp = NULL; callbacks->getPresentationTimeStamp = NULL; callbacks->isDataReady = NULL; callbacks->compare = NULL; callbacks->dataBecameReadyNotification = NULL; CMItemCount capacity = 4; OSStatus s = CMBufferQueueCreate(allocator, capacity, callbacks, queue); NSLog(@"QUEUE: %x", queue); NSLog(@"STATUS: %i", s); with timeCallback: CMTime timeCallback(CMBufferRef buf, void *refcon){ return CMTimeMake(1, 1); } and queue is: CMBufferQueueRef* queue; queue creations fails (queue = 0) and returns a status of: kCMBufferQueueError_RequiredParameterMissing = -12761, The callbacks variable is correctly initialized, at least the debugger says so. Somebody have played arround with CMBufferQueue? google doesn't know about that! Thanks

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• How can I add a "Loading...Please wait..." feature?

  - by Rob

  I have a very simple table on my website, that displays different URL's. I have an input field where I can type in a URL and click 'Submit' to add additional URL's. However, I want to add an MD5 grabbing feature to this, using @md5_file(); to grab the MD5 of the URL and check to make sure it's the MD5 it should be, before adding it to the database. However it may take a few seconds for it to grab the MD5 and compare it, so I would like to add a little bit of text, like "Processing...Please wait..." while it does the comparing, and then once it's compared I want that text to go away. I've never done this before, or even though about doing it so I have no idea where to start. I'll go ahead and put javascript as a tag for this, since I'm guessing it would be done with javascript, but I really have no idea. I don't think it's possible with PHP, but again, I have no idea. Any suggestions?

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• getting a tiled image collection on the iPad (deepzoom)

  - by Chris B

  I have a set of tiled image collections created via microsoft's deep zoom composer, and a silverlight app that currently consumes them for display via MultiScaleImage - it's all working pretty well - I'd just like to get some experience with iPad programming and have a couple of ideas for some ipad applications. All my ideas rely on me being able to display/manipulate these tiled image sets (on the iPad). I just picked up a iMac to facilitate this. I'm not seeing any objective-c / cocoa-touch libraries for this though, so am assuming I will have to roll my own. (Saw the seadragon ajax component, which is pretty slick, but I'm dealing with collections here, which it doesn't support. I would also like to roll this as a native app just to get the experience). The only open source project I found for displaying/manipulating the tiled image sets was Openzoom -a flash component. I'm not to familiar with actionscript either (python, java, c#, and c are the only languages I have really used), but briefly inspecting the code I didn't really have any issues with it and can probably use it for hints on how to swap the tiles in and out, etc.. But, as I'm pretty new to obj-c/cocoa-touch, some pointers in the right direction would be appreciated. 1) Are there any other projects out there I am missing, or is openzoom my best bet for some reference? 2) Should I be trying to do this display in the UIKit framework, or should I do it as an OpenGL display? 3) Any other suggestions/pointers that I didn't think to ask.

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• What's correct way to remove a boost::shared_ptr from a list?

  - by Catskul

  I have a std::list of boost::shared_ptr<T> and I want to remove an item from it but I only have a pointer of type T* which matches one of the items in the list. However I cant use myList.remove( tPtr ) I'm guessing because shared_ptr does not implement == for its template argument type. My immediate thought was to try myList.remove( shared_ptr<T>(tPtr) ) which is syntactically correct but it will crash from a double delete since the temporary shared_ptr has a separate use_count. std::list< boost::shared_ptr<T> > myList; T* tThisPtr = new T(); // This is wrong; only done for example code. // stand-in for actual code in T using // T's actual "this" pointer from within T { boost::shared_ptr<T> toAdd( tThisPtr ); // typically would be new T() myList.push_back( toAdd ); } { //T has pointer to myList so that upon a certain action, // it will remove itself romt the list //myList.remove( tThisPtr); //doesn't compile myList.remove( boost::shared_ptr<T>(tThisPtr) ); // compiles, but causes // double delete } The only options I see remaining are to use std::find with a custom compare, or to loop through the list brute force and find it myself, but it seems there should be a better way. Am I missing something obvious, or is this just too non-standard a use to be doing a remove the clean/normal way?

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• Synchronizing files between Linux servers, through FTP

  - by Daniel Magliola

  I have the following configuration of servers: 1 central linux server, a VPS 8 satellite linux servers, "crappy shared hostings" I have a bunch of files that I need to have in all servers. Right now i'm copying them everywhere manually, but I want to be able to copy them to the central server, and then have a scheduled process that runs every now and then and synchronizes them (only outwardly, no need to try to find "new" files in the satellite servers). There are a couple of catches though: I can't have any custom software in the satellite servers, or do strange command line things that'll auto connect to them and send the files directly. I know this is the way these kinds of things are normally done, but the satellite servers are crappy shared hosting ones where I have absolutely no control over anything. I need to send the files over FTP I also need to have, in my central server, a list of the files that are available in each of the satellite servers, to make sure they are ready before I send traffic to them. If I were to do this manually, the steps would be: get the list of files in a satellite server compare to my own, and send the files that are missing get the list of files again, and store it in my central database. I'd like to know what tools are out there that can alleviate as much of this as possible, first the syncing, and then the "getting the list of files available in the other server". I'm going to be doing everything from PHP, not sure if there are good tools to "use FTP from PHP", which i'm pretty sure i'll have to do for step 3 at least. Thanks in advance for any ideas! Daniel

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• [C#][XNA 3.1] How can I host two different XNA windows inside one Windows Form?

  - by secutos

  I am making a Map Editor for a 2D tile-based game. I would like to host two XNA controls inside the Windows Form - the first to render the map; the second to render the tileset. I used the code here to make the XNA control host inside the Windows Form. This all works very well - as long as there is only one XNA control inside the Windows Form. But I need two - one for the map; the second for the tileset. How can I run two XNA controls inside the Windows Form? While googling, I came across the terms "swap chain" and "multiple viewports", but I can't understand them and would appreciate support. Just as a side note, I know the XNA control example was designed so that even if you ran 100 XNA controls, they would all share the same GraphicsDevice - essentially, all 100 XNA controls would share the same screen. I tried modifying the code to instantiate a new GraphicsDevice for each XNA control, but the rest of the code doesn't work. The code is a bit long to post, so I won't post it unless someone needs it to be able to help me. Thanks in advance.

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• % style macros not supported in some C++/CLI project property pages under VS2010?

  - by Dave Foster

  We're currently evaluating VS2010 and have upgraded our VS2008 C++/CLI project to the new .vcxproj format. I've noticed that a certain property we had set in the project settings did not get translated properly. Under Configuration Properties - Managed Resources - Resource Logical Name, we used to have (in VS2008) the setting: $(IntDir)\$(RootNamespace).$(InputName).resources which indicated that all .resx files were to compile into OurLib.SomeForm.resources inside of the assembly. (the Debug portion is dropped when assembled) According to MSDN, the $(InputName) macro no longer exists and should be replaced with %(Filename). However, when translating the above line to swap those macros, it does not seem to ever expand. The second .resx file it tries to compile, I get a "LINK : fatal error LNK1316: duplicate managed resource name 'Debug\OurLib.%(Filename).resources". This indicates to me that the % style macros are not being expanded here, at least in this specific property. If we don't set anything in that property, the default behavior seems to be to add the subdirectory as a prefix, such as: OurLib.Forms.SomeForm.resources where Forms is the subdir of our project that the .resx file lives. This only occurs when the .resx file is in an immediate subdirectory of the project being built. If a .resx file exists somewhere else on disk (aka ..\OtherLib\Forms\SomeForm2.resx) this prefix is NOT added. This is causing an issue with loading form resources, as it does not account for this possible prefix, even though we are using the standard Forms Designer method of getting at resources: System::ComponentModel::ComponentResourceManager^ resources = (gcnew System::ComponentModel::ComponentResourceManager(SomeForm::typeid)); and do not specify the .resources file by name. The issue I've just described may not be the same as the original question, but if I were to fix the Resource Logical Name issue I think this would all go away. Does anyone have any information about these % macros and where they are allowed to be used?

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• Validate XSD with XML .

  - by munish

  I want to know how to validate XML with XSD . XML is not of an element type but a complex type . Since validator class's validate method compare only element type. So basically I want to valide XSD's complex type with an XML. e.g. Basic XSD below xs:element name="Customer"> <xs:complexType> <xs:sequence> <xs:element name="Dob" type="xs:date" /> <xs:element name="Address"> <xs:complexType> <xs:sequence> <xs:element name="Line1" type="xs:string" /> <xs:element name="Line2" type="xs:string" /> </xs:sequence> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> We can assume we have multiple complex type in the Customer element. MY XML is <Address> <Line1>34 thingy street, someplace</Line1> <Line2>sometown, w1w8uu </Line2> </Address> How I validate my XML with XSD. Kindly post your suggestions in java

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• Which Java library for Binary Decision Diagrams?

  - by reprogrammer

  A Binary Decision Diagram (BDD) is a data structure to represent boolean functions. I'd like use this data structure in a Java program. My search for Java based BDD libraries resulted into the following packages. Java Decision Diagram Libraries JavaBDD JDD If you know of any other BDD libraries available for Java programs, please let me know so that I add it to the list above. If you have used any of these libraries, please tell me about your experience with the library. In particular, I'd like you to compare the available libraries along the following dimensions. Quality. Is the library mature and reasonably bug free? Performance. How do you evaluate the performance of the library? Support. Could you easily get support whenever you encountered a problem with the library? Was the library well documented? Ease of use. Was the API well designed? Could you install and use the library quickly and easily? Please mention the version of the library that you are evaluating.

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• Debug NAudio MP3 reading difference?

  - by Conrad Albrecht

  My code using NAudio to read one particular MP3 gets different results than several other commercial apps. Specifically: My NAudio-based code finds ~1.4 sec of silence at the beginning of this MP3 before "audible audio" (a drum pickup) starts, whereas other apps (Windows Media Player, RealPlayer, WavePad) show ~2.5 sec of silence before that same drum pickup. The particular MP3 is "Like A Rolling Stone" downloaded from Amazon.com. Tested several other MP3s and none show any similar difference between my code and other apps. Most MP3s don't start with such a long silence so I suspect that's the source of the difference. Debugging problems: I can't actually find a way to even prove that the other apps are right and NAudio/me is wrong, i.e. to compare block-by-block my code's results to a "known good reference implementation"; therefore I can't even precisely define the "error" I need to debug. Since my code reads thousands of samples during those 1.4 sec with no obvious errors, I can't think how to narrow down where/when in the input stream to look for a bug. The heart of the NAudio code is a P/Invoke call to acmStreamConvert(), which is a Windows "black box" call which I can't think how to error-check. Can anyone think of any tricks/techniques to debug this?

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• PHP str_replace and preg_replace work on one server but not another

  - by retailevolved

  I have a simple function on a php page that takes a url such as: http://myurl.com/mypage.html?param1=value1 and converts it to: http://myurl.com/searchpage.html?param1=value1 All it does it swap out the page.html portion. To do this, I use the following: $currentUrl = $this-getCurrentUrl(); // Grabs the current url, i.e 'http://myurl.com/mypage.html?param1=value1' // Derive a search pattern from the current url $pattern = "/" . str_replace(array("/", ".", "-"), array("\\/", "\\.", "\\-"), $currentUrl) . "/"; // get rid of the 'mypage.html' $newUrl = preg_replace($pattern, 'http://myurl.com/', $currentUrl); // replace the question mark with the correct page $newUrl = str_replace("/?", "/searchpage.html?", $newUrl); The above code is not the exact code but is a good representation. It works beautifully on one server, but when I push to production, the preg_replace does not work. I originally attempted to use str_replace. It also works on my local development machine, but not on the production server. I have confirmed that the URL variables are coming in correctly. Any ideas?

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• Simple ASP.NET MVC views without writing a controller

  - by Jake Stevenson

  We're building a site that will have very minimal code, it's mostly just going to be a bunch of static pages served up. I know over time that will change and we'll want to swap in more dynamic information, so I've decided to go ahead and build a web application using ASP.NET MVC2 and the Spark view engine. There will be a couple of controllers that will have to do actual work (like in the /products area), but most of it will be static. I want my designer to be able to build and modify the site without having to ask me to write a new controller or route every time they decide to add or move a page. So if he wants to add a "http://mysite.com/News" page he can just create a "News" folder under Views and put an index.spark page within it. Then later if he decides he wants a /News/Community page, he can drop a community.spark file within that folder and have it work. I'm able to have a view without a specific action by making my controllers override HandleUnknownAction, but I still have to create a controller for each of these folders. It seems silly to have to add an empty controller and recompile every time they decide to add an area to the site. Is there any way to make this easier, so I only have to write a controller and recompile if there's actual logic to be done? Some sort of "master" controller that will handle any requests where there was no specific controller defined?

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• What should be the "trunk" development, or release

  - by Nix

  I have the unfortunate opportunity of source control via Borland's StarTeam. It unfortunately does very few things well, and one supreme weakness is its view management. I love SVN and come from an SVN mindset. Our issue is post production release we are spending countless hours merging changes into a "production support" environment. Please do not harass me this was not my doing, I inherited it and am trying to present a better way of managing the repository. It is not an option to switch to a different SCM tool. Current setup Product.1.0 (TRUNK, current production code, and at this level are pending bug fixes) Product.2.0(true trunk anything checked in gets tested, and then released next production cycle, a lot of changes occur in this view) My proposal is going to be to swap them, have all development be done on the trunk (Production), tag on releases, and as needed create child views to represent production support bug fixes. Production Production.2.0.SP.1 I can not find any documentation to support the above proposal so I am trying to get feedback on whether or not the change is a good idea and if there is anything you would recommend doing differently.

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• T-SQL - Left Outer Joins - Fileters in the where clause versus the on clause.

  - by Greg Potter

  I am trying to compare two tables to find rows in each table that is not in the other. Table 1 has a groupby column to create 2 sets of data within table one. groupby number ----------- ----------- 1 1 1 2 2 1 2 2 2 4 Table 2 has only one column. number ----------- 1 3 4 So Table 1 has the values 1,2,4 in group 2 and Table 2 has the values 1,3,4. I expect the following result when joining for Group 2: `Table 1 LEFT OUTER Join Table 2` T1_Groupby T1_Number T2_Number ----------- ----------- ----------- 2 2 NULL `Table 2 LEFT OUTER Join Table 1` T1_Groupby T1_Number T2_Number ----------- ----------- ----------- NULL NULL 3 The only way I can get this to work is if I put a where clause for the first join: PRINT 'Table 1 LEFT OUTER Join Table 2, with WHERE clause' select table1.groupby as [T1_Groupby], table1.number as [T1_Number], table2.number as [T2_Number] from table1 LEFT OUTER join table2 --****************************** on table1.number = table2.number --****************************** WHERE table1.groupby = 2 AND table2.number IS NULL and a filter in the ON for the second: PRINT 'Table 2 LEFT OUTER Join Table 1, with ON clause' select table1.groupby as [T1_Groupby], table1.number as [T1_Number], table2.number as [T2_Number] from table2 LEFT OUTER join table1 --****************************** on table2.number = table1.number AND table1.groupby = 2 --****************************** WHERE table1.number IS NULL Can anyone come up with a way of not using the filter in the on clause but in the where clause? The context of this is I have a staging area in a database and I want to identify new records and records that have been deleted. The groupby field is the equivalent of a batchid for an extract and I am comparing the latest extract in a temp table to a the batch from yesterday stored in a partioneds table, which also has all the previously extracted batches as well. Code to create table 1 and 2: create table table1 (number int, groupby int) create table table2 (number int) insert into table1 (number, groupby) values (1, 1) insert into table1 (number, groupby) values (2, 1) insert into table1 (number, groupby) values (1, 2) insert into table2 (number) values (1) insert into table1 (number, groupby) values (2, 2) insert into table2 (number) values (3) insert into table1 (number, groupby) values (4, 2) insert into table2 (number) values (4)

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• Using ARIMA to model and forecast stock prices using user-friendly stats program

  - by Brian

  Hi people, Can anyone please offer some insight into this for me? I'm coming from a functional magnetic resonance imaging research background where I analyzed a lot of time series data, and I'd like to analyze the time series of stock prices (or returns) by: 1) modeling a successful stock in a particular market sector and then cross-correlating the time series of this historically successful stock with that of other newer stocks to look for significant relationships; 2) model a stock's price time series and use forecasting (e.g., exponential smoothing) to predict future values of it. I'd like to use non-linear modeling methods (ARIMA and ARCH) to do this. Several questions: How often do ARIMA and ARCH modeling methods (given that the individual who implements them does so accurately) actually fit the stock time series data they target, and what is the optimal fit I can expect? Is the extent to which this model fits the data commensurate with the extent to which it predicts this stock time series' future values? Rather than randomly selecting stocks to compare or model, if profit is my goal, what is an efficient approach, if any, to selecting the stocks I'm going to analyze? Which stats program is the most user-friendly for this? Any thoughts on this would be great and would go a long way for me. Thanks, Brian

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• Join + IEqualityComparer<T> and HashCode

  - by Jesus Rodriguez

  Im writing my own LINQ reference but Im getting troubles with some of the more complicated operators implementations. There is a Join implementation that takes a IEqualityComparer Im getting just crazy. Im trying to understand it first before I write (obviously) Image this two lists: List<string> initials = new List<string> {"A", "B", "C", "D", "E"}; List<string> words = new List<string> {"Ant", "Crawl", "Pig", "Boat", "Elephant", "Arc"}; Nothing weird here. I want to join both lists by the Initial, something like: Initial=A Word=Ant Initial=A Word=Arc Initial=B Word=Boat ... I need a comparator, I wrote this: public class InitialComparator : IEqualityComparer<string> { public bool Equals(string x, string y) { return x.StartsWith(y); } public int GetHashCode(string obj) { return obj[0].GetHashCode(); } } The Join itself: var blah = initials.Join(words, initial => initial, word => word, (initial, word) => new {Initial = initial, Word = word}, new InitialComparator()); It's the first time Im using HashCodes, after a good session of debugging I see that every word go to the comparator and look at its HashCode, if another word has the same HashCode it calls equals. Since I want to compare just the initial I though that I just need the first letter Hash (Am I wrong?) The thing is that this is not working correctly. Its says that "Ant" and "Arc" are equals, Ok, its comparing every word in the same list or not, But it adds only the last word it finds, in this case Arc, ignoring Ant and Ant is equals to "A" too... If I put "Ant" and "Ant" it add both. In short, What is the way of doing something like that? I know that Im doing something wrong. Thank you.

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• Quickest algorithm for finding sets with high intersection

  - by conradlee

  I have a large number of user IDs (integers), potentially millions. These users all belong to various groups (sets of integers), such that there are on the order of 10 million groups. To simplify my example and get to the essence of it, let's assume that all groups contain 20 user IDs (i.e., all integer sets have a cardinality of 100). I want to find all pairs of integer sets that have an intersection of 15 or greater. Should I compare every pair of sets? (If I keep a data structure that maps userIDs to set membership, this would not be necessary.) What is the quickest way to do this? That is, what should my underlying data structure be for representing the integer sets? Sorted sets, unsorted---can hashing somehow help? And what algorithm should I use to compute set intersection)? I prefer answers that relate C/C++ (especially STL), but also any more general, algorithmic insights are welcome. Update Also, note that I will be running this in parallel in a shared memory environment, so ideas that cleanly extend to a parallel solution are preferred.

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