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• Significance in R

  - by Gemsie

  Ok, this is quite hard to explain, but I'm at a complete loss what to do. I'm a relative newcomer to R and although I can completely admire how powerful it is, I'm not too good at actually using it.... Basically, I have some very contrived data that I need to analyse (it wasn't me who chose this, I can assure you!). I have the right and left hand lengths of lots of people, as well as some numeric data that shows their sociability. Now I would like to know if people who have significantly different lengths of hand are more or less sociable than those who have the same (leading into the research that 'symmetrical' people are more sociable and intelligent, etc. I have got as far as loading the data into R, then I have no idea where to go from there. How on Earth do I start to separate those who are close to symmetrical to those who aren't to then start to do the analysis? Ok, using Sasha's great advice, I did the cor.test and got the following: Pearson's product-moment correlation data: measurements$l.hand - measurements$r.hand and measurements$sociable t = 0.2148, df = 150, p-value = 0.8302 alternative hypothesis: true correlation is not equal to 0 95 percent confidence interval: -0.1420623 0.1762437 sample estimates: cor 0.01753501 I have never used this test before, so am unsure how to intepret it...you wouldn't think I was on my fourth Scientific degree would you?! :(

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• Return lines in input code causing gaps/whitespace between elements in output?

  - by Jenny Zhang

  I am trying to put images next to each other on a webpage. Here is my HTML: <img class="pt" src="Yellow Tulip.jpg" title="Yellow Tulip" alt="Yellow Tulip" /> <img class="pt" src="Pink Tulip.jpg" title="Pink Tulip" alt="Pink Tulip" /> <img class="pt" src="Purple Tulip.jpg" title="Purple Tulip" alt="Purple Tulip" /> However, on my webpage, this shows a gap between each image. I've noticed that once I remove the return line that makes the elements separate and readable and instead just put all the elements on one line, the gaps go away. <img class="pt" src="Yellow Tulip.jpg" title="Yellow Tulip" alt="Yellow Tulip" /><img class="pt" src="Pink Tulip.jpg" title="Pink Tulip" alt="Pink Tulip" /><img class="pt" src="Purple Tulip.jpg" title="Purple Tulip" alt="Purple Tulip" /> Is there anyway I can achieve the output of the latter but still have the code/input look like the former? I really like the readability that the return lines (enter spaces) bring to the code, but I don't want the whitespace it creates on the actual page. If someone could explain why this is and/or how to fix it, I'd be really grateful! :)

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• Strange Bug in iPhone SDK

  - by Crazer

  Hi all, I found a strange bug in iphone sdk. I try to explain it: I have a number of uibuttons in a view. They are all just images. Every buttons has a title but that is not displayed so you just see the images (all 80x80). I made it all in IB. In my code I position those buttons. Here's a snippet of that code: for(NSString *iconObject in iconArray){ //retrieve UIButtons from dictionary iconButton = [allIconsDictionary objectForKey:iconObject]; iconButton.hidden = NO; //position and resize icon Buttons iconButton.frame = CGRectMake((79 * col) + 28, (70 * row) + 70, 80 ,80); col++; //five buttons in a row if(col%5 == 0){ row++; col = 0; } } That works like it should. But for all buttons that title starts with a 't' the title displays in the simulator (also on the device). The title of the other buttons are not shown just those where the title starts with a 't'. I have no clue what this could be?! I hope I could describe the problem.

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• accessing private variable from member function in PHP

  - by Carson Myers

  I have derived a class from Exception, basically like so: class MyException extends Exception { private $_type; public function type() { return $this->_type; //line 74 } public function __toString() { include "sometemplate.php"; return ""; } } Then, I derived from MyException like so: class SpecialException extends MyException { private $_type = "superspecial"; } If I throw new SpecialException("bla") from a function, catch it, and go echo $e, then the __toString function should load a template, display that, and then not actually return anything to echo. This is basically what's in the template file <div class="<?php echo $this->type(); ?>class"> <p> <?php echo $this->message; ?> </p> </div> in my mind, this should definitely work. However, I get the following error when an exception is thrown and I try to display it: Fatal error: Cannot access private property SpecialException::$_type in C:\path\to\exceptions.php on line 74 Can anyone explain why I am breaking the rules here? Am I doing something horribly witty with this code? Is there a much more idiomatic way to handle this situation? The point of the $_type variable is (as shown) that I want a different div class to be used depending on the type of exception caught.

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• Why doesn't access database update?

  - by Ryan

  Recently I met a strange problem, see code snips as below: var sqlCommand: string; connection: TADOConnection; qry: TADOQuery; begin connection := TADOConnection.Create(nil); try connection.ConnectionString := 'Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Test.MDB;Persist Security Info=False'; connection.Open(); qry := TADOQuery.Create(nil); try qry.Connection := connection; qry.SQL.Text := 'Select * from aaa'; qry.Open; qry.Append; qry.FieldByName('TestField1').AsString := 'test'; qry.Post; beep; finally qry.Free; end; finally connection.Free; end; end; First, Create a new access database named test.mdb and put it under the directory of this test project, we can create a new table named aaa in it which has only one text type field named TestField1. We set a breakpoint at line of "beep", then lunch the test application under ide debug mode, when ide stops at the breakpoint line (qry.post has been executed), at this time we use microsoft access to open test.mdb and open table aaa you will find there are no any changes in table aaa, if you let the ide continue running after pressing f9 you can find a new record is inserted in to table aaa, but if you press ctrl+f2 to terminate the application at the breakpoint, you will find the table aaa has no record been inserted, but in normal circumstance, a new record should be inserted in to the table aaa after qry.post executed. who can explain this problem , it troubles me so long time. thanks !!! BTW, the ide is delphi 2010, and the access mdb file is created by microsoft access 2007 under windows 7

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• Are .NET 4.0 Runtime slower than .NET 2.0 Runtime?

  - by DxCK

  After I upgraded my projects to .NET 4.0 (With VS2010) I realized than they run slower than they were in .NET 2.0 (VS2008). So i decided to benchmark a simple console application in both VS2008 & VS2010 with various Target Frameworks: using System; using System.Diagnostics; using System.Reflection; namespace RuntimePerfTest { class Program { static void Main(string[] args) { Console.WriteLine(Assembly.GetCallingAssembly().ImageRuntimeVersion); Stopwatch sw = new Stopwatch(); while (true) { sw.Reset(); sw.Start(); for (int i = 0; i < 1000000000; i++) { } TimeSpan elapsed = sw.Elapsed; Console.WriteLine(elapsed); } } } } Here is the results: VS2008 Target Framework 2.0: ~0.25 seconds Target Framework 3.0: ~0.25 seconds Target Framework 3.5: ~0.25 seconds VS2010 Target Framework 2.0: ~3.8 seconds Target Framework 3.0: ~3.8 seconds Target Framework 3.5: ~1.51 seconds Target Framework 3.5 Client Profile: ~3.8 seconds Target Framework 4.0: ~1.01 seconds Target Framework 4.0 Client Profile: ~1.01 seconds My initial conclusion is obviously that programs compiled with VS2008 working faster than programs compiled with VS2010. Can anyone explain those performance changes between VS2008 and VS2010? and between different Target Frameworks inside VS2010 itself?

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• what is meant by normalization in huge pointers

  - by wrapperm

  Hi, I have a lot of confusion on understanding the difference between a "far" pointer and "huge" pointer, searched for it all over in google for a solution, couldnot find one. Can any one explain me the difference between the two. Also, what is the exact normalization concept related to huge pointers. Please donot give me the following or any similar answers: "The only difference between a far pointer and a huge pointer is that a huge pointer is normalized by the compiler. A normalized pointer is one that has as much of the address as possible in the segment, meaning that the offset is never larger than 15. A huge pointer is normalized only when pointer arithmetic is performed on it. It is not normalized when an assignment is made. You can cause it to be normalized without changing the value by incrementing and then decrementing it. The offset must be less than 16 because the segment can represent any value greater than or equal to 16 (e.g. Absolute address 0x17 in a normalized form would be 0001:0001. While a far pointer could address the absolute address 0x17 with 0000:0017, this is not a valid huge (normalized) pointer because the offset is greater than 0000F.). Huge pointers can also be incremented and decremented using arithmetic operators, but since they are normalized they will not wrap like far pointers." Here the normalization concept is not very well explained, or may be I'm unable to understand it very well. Can anyone try explaining this concept from a beginners point of view. Thanks, Rahamath

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• html doctype adds whitespace ??

  - by pstanton

  can someone please explain to me why having a doctype of <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> and <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"> render the following block differently under firefox? <table style="border-collapse:collapse; margin:0; padding:0;"> <tr> <td style="border:1px solid red; margin:0; padding:0;"><img src="http://images.smh.com.au/2010/06/01/1533814/th_park-90x60.jpg" style="border:none; padding:0; margin:0;" /></td> </tr> </table> using 'Transitional', there is no white space below the image, using 'Strict' there is! 2nd question, using strict, is it at all possible to remove this whitespace?

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• Why is Func<T> ambiguous with Func<IEnumerable<T>>?

  - by Matt Hamilton

  This one's got me flummoxed, so I thought I'd ask here in the hope that a C# guru can explain it to me. Why does this code generate an error? class Program { static void Main(string[] args) { Foo(X); // the error is on this line } static String X() { return "Test"; } static void Foo(Func<IEnumerable<String>> x) { } static void Foo(Func<String> x) { } } The error in question: Error 1 The call is ambiguous between the following methods or properties: 'ConsoleApplication1.Program.Foo(System.Func<System.Collections.Generic.IEnumerable<string>>)' and 'ConsoleApplication1.Program.Foo(System.Func<string>)' C:\Users\mabster\AppData\Local\Temporary Projects\ConsoleApplication1\Program.cs 12 13 ConsoleApplication1 It doesn't matter what type I use - if you replace the "String" declarations with "int" in that code you'll get the same sort of error. It's like the compiler can't tell the difference between Func<T> and Func<IEnumerable<T>>. Can someone shed some light on this?

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• What is the difference between these two linq implementations?

  - by Mahesh Velaga

  I was going through Jon Skeet's Reimplemnting Linq to Objects series. In the implementation of where article, I found the following snippets, but I don't get what is the advantage that we are gettting by splitting the original method into two. Original Method: // Naive validation - broken! public static IEnumerable<TSource> Where<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { if (source == null) { throw new ArgumentNullException("source"); } if (predicate == null) { throw new ArgumentNullException("predicate"); } foreach (TSource item in source) { if (predicate(item)) { yield return item; } } } Refactored Method: public static IEnumerable<TSource> Where<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { if (source == null) { throw new ArgumentNullException("source"); } if (predicate == null) { throw new ArgumentNullException("predicate"); } return WhereImpl(source, predicate); } private static IEnumerable<TSource> WhereImpl<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { foreach (TSource item in source) { if (predicate(item)) { yield return item; } } } Jon says - Its for eager validation and then defferring for the rest of the part. But, I don't get it. Could some one please explain it in a little more detail, whats the difference between these 2 functions and why will the validations be performed in one and not in the other eagerly? Conclusion/Solution: I got confused due to my lack of understanding on which functions are determined to be iterator-generators. I assumed that, it is based on signature of a method like IEnumerable<T>. But, based on the answers, now I get it, a method is an iterator-generator if it uses yield statements.

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• Linq2Sql: query - subquery optimisation

  - by Budda

  I have the following query: IList<InfrStadium> stadiums = (from sector in DbContext.sectors where sector.Type=typeValue select new InfrStadium(sector.TeamId) ).ToList(); and InfrStadium class constructor: private InfrStadium(int teamId) { IList<Sector> teamSectors = (from sector in DbContext.sectors where sector.TeamId==teamId select sector) .ToList<>(); ... work with data } Current implementation perform 1+n queries, where n - number of records fetched the 1st time. I want to optimize that. And another one I would love to do using 'group' operator in way like this: IList<InfrStadium> stadiums = (from sector in DbContext.sectors group sector by sector.TeamId into team_sectors select new InfrStadium(team_sectors.Key, team_sectors) ).ToList(); with appropriate constructor: private InfrStadium(int iTeamId, IEnumerable<InfrStadiumSector> eSectors) { IList<Sector> teamSectors = eSectors.ToList(); ... work with data } But attempt to launch query causes the following error: Expression of type 'System.Int32' cannot be used for constructor parameter of type 'System.Collections.Generic.IEnumerable`1[InfrStadiumSector]' Question 1: Could you please explain, what is wrong here, I don't understand why 'team_sectors' is applied as 'System.Int32'? I've tried to change query a little (replace IEnumerable with IQueryeable): IList<InfrStadium> stadiums = (from sector in DbContext.sectors group sector by sector.TeamId into team_sectors select new InfrStadium(team_sectors.Key, team_sectors.AsQueryable()) ).ToList(); with appropriate constructor: private InfrStadium(int iTeamId, IQueryeable<InfrStadiumSector> eSectors) { IList<Sector> teamSectors = eSectors.ToList(); ... work with data } In this case I've received another but similar error: Expression of type 'System.Int32' cannot be used for parameter of type 'System.Collections.Generic.IEnumerable1[InfrStadiumSector]' of method 'System.Linq.IQueryable1[InfrStadiumSector] AsQueryableInfrStadiumSector' Question 2: Actually, the same question: can't understand at all what is going on here... P.S. I have another to optimize query idea (describe here: Linq2Sql: query optimisation) but I would love to find a solution with 1 request to DB).

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• How do virtual destructors work?

  - by Prabhu

  Few hours back I was fiddling with a Memory Leak issue and it turned out that I really got some basic stuff about virtual destructors wrong! Let me put explain my class design. class Base { virtual push_elements() {} }; class Derived:public Base { vector<int> x; public: void push_elements(){ for(int i=0;i <5;i++) x.push_back(i); } }; void main() { Base* b = new Derived(); b->push_elements(); delete b; } The bounds checker tool reported a memory leak in the derived class vector. And I figured out that the destructor is not virtual and the derived class destructor is not called. And it surprisingly got fixed when I made the destructor virtual. Isn't the vector deallocated automatically even if the derived class destructor is not called? Is that a quirk in BoundsChecker tool or is my understanding of virtual destructor wrong?

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• Strange results from OdbcDataReader reading Sqlite DB

  - by stout

  This method returns some strange results, and was wondering if someone could explain why this is happening, and possibly a solution to get my desired results. Results: FileName = what I'd expect FileSize = what I'd expect Buffer = all bytes = 0 BytesRead = 0 BlobString = string of binary data FieldType = BLOB (what I'd expect) ColumnType = System.String Furthermore, if the file is greater than a few KB, the reader throws an exception stating the StringBuilder capacity argument must be greater than zero (presummably because the size is greater than Int32.MaxValue). I guess my question is how does one properly read large BLOBs from an OdbcDataReader? public static String SaveBinaryFile(String Key) { try { Connect(); OdbcCommand Command = new OdbcCommand("SELECT [_filename_],[_filesize_],[_content_] FROM [_sys_content] WHERE [_key_] = '" + Key + "';", Connection); OdbcDataReader Reader = Command.ExecuteReader(CommandBehavior.SequentialAccess); if (Reader.HasRows == false) return null; String FileName = Reader.GetString(0); int FileSize = int.Parse(Reader.GetString(1)); byte[] Buffer = new byte[FileSize]; long BytesRead = Reader.GetBytes(2, 0, Buffer, 0, FileSize); String BlobString = (String)Reader["_content_"]; String FieldType = Reader.GetDataTypeName(2); Type ColumnType = Reader.GetFieldType(2); return null; } catch (Exception ex) { Tools.ErrorHandler.Catch(ex); return null; } }

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• Intel MKL memory management and exceptions

  - by Andrew

  Hello everyone, I am trying out Intel MKL and it appears that they have their own memory management (C-style). They suggest using their MKL_malloc/MKL_free pairs for vectors and matrices and I do not know what is a good way to handle it. One of the reasons for that is that memory-alignment is recommended to be at least 16-byte and with these routines it is specified explicitly. I used to rely on auto_ptr and boost::smart_ptr a lot to forget about memory clean-ups. How can I write an exception-safe program with MKL memory management or should I just use regular auto_ptr's and not bother? Thanks in advance. EDIT http://software.intel.com/sites/products/documentation/hpc/mkl/win/index.htm this link may explain why I brought up the question UPDATE I used an idea from the answer below for allocator. This is what I have now: template <typename T, size_t TALIGN=16, size_t TBLOCK=4> class aligned_allocator : public std::allocator<T> { public: pointer allocate(size_type n, const void *hint) { pointer p = NULL; size_t count = sizeof(T) * n; size_t count_left = count % TBLOCK; if( count_left != 0 ) count += TBLOCK - count_left; if ( !hint ) p = reinterpret_cast<pointer>(MKL_malloc (count,TALIGN)); else p = reinterpret_cast<pointer>(MKL_realloc((void*)hint,count,TALIGN)); return p; } void deallocate(pointer p, size_type n){ MKL_free(p); } }; If anybody has any suggestions, feel free to make it better.

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• SQLAlchemy Custom Type Which Contains Multiple Columns

  - by Kekoa

  I would like to represent a datatype as a single column in my model, but really the data will be stored in multiple columns in the database. I cannot find any good resources on how to do this in SQLAlchemy. I would like my model to look like this(this is a simplified example using geometry instead of my real problem which is harder to explain): class 3DLine(DeclarativeBase): start_point = Column(my.custom.3DPoint) end_point = Column(my.custom.3DPoint) This way I could assign an object with the (x, y, z) components of the point at once without setting them individually. If I had to separate each component, this could get ugly, especially if each class has several of these composite objects. I would combine the values into one encoded field except that I need to query each value separately at times. I was able to find out how to make custom types using a single column in the documentation. But there's no indication that I can map a single type to multiple columns. I suppose I could accomplish this by using a separate table, and each column would be a foreign key, but in my case I don't think it makes sense to have a one to one mapping for each point to a separate table, and this still does not give the ability to set the related values all at once.

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• Validation problem with a 'JotForm' template

  - by Thomas

  A client sent me a form template they had created using jotform.com to implement on their wordpress site. The form template is supposed to hide part of the form until the user clicks the 'next' button. At which point a script is supposed to validate all of the input fields the user has presumably filled out and then display the rest of the form. While I have successfully managed to get the form to display the next part of the form when the user clicks 'next', it fails to validate the input fields. Its kind of difficult to explain without a huge block of text so it is probably easier to show you: The original working template that the customer sent me: http://www.loftist.com/jotform/List_Your_Loft.html The problem child: http://www.loftist.com/?page_id=78 If you just click on one of the input fields and then click elsewhere on the page, the input fields successfully return a validation error message and prevent the user from clicking on the 'next' button. However, if you simply click on the next button than the next set of fields get displayed. Any thoughts? What am I doing wrong here? Im convinced this must be a really simple problem but Im not sure what it could be....

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• Java Matcher groups: Understanding The difference between "(?:X|Y)" and "(?:X)|(?:Y)"

  - by user358795

  Can anyone explain: Why the two patterns used below give different results? (answered below) Why the 2nd example gives a group count of 1 but says the start and end of group 1 is -1? public void testGroups() throws Exception { String TEST_STRING = "After Yes is group 1 End"; { Pattern p; Matcher m; String pattern="(?:Yes|No)(.*)End"; p=Pattern.compile(pattern); m=p.matcher(TEST_STRING); boolean f=m.find(); int count=m.groupCount(); int start=m.start(1); int end=m.end(1); System.out.println("Pattern=" + pattern + "\t Found=" + f + " Group count=" + count + " Start of group 1=" + start + " End of group 1=" + end ); } { Pattern p; Matcher m; String pattern="(?:Yes)|(?:No)(.*)End"; p=Pattern.compile(pattern); m=p.matcher(TEST_STRING); boolean f=m.find(); int count=m.groupCount(); int start=m.start(1); int end=m.end(1); System.out.println("Pattern=" + pattern + "\t Found=" + f + " Group count=" + count + " Start of group 1=" + start + " End of group 1=" + end ); } } Which gives the following output: Pattern=(?:Yes|No)(.*)End Found=true Group count=1 Start of group 1=9 End of group 1=21 Pattern=(?:Yes)|(?:No)(.*)End Found=true Group count=1 Start of group 1=-1 End of group 1=-1

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• I am confused about how to use @SessionAttributes

  - by yusaku

  I am trying to understand architecture of Spring MVC. However, I am completely confused by behavior of @SessionAttributes. Please look at SampleController below , it is handling post method by SuperForm class. In fact, just field of SuperForm class is only binding as I expected. However, After I put @SessionAttributes in Controller, handling method is binding as SubAForm. Can anybody explain me what happened in this binding. ------------------------------------------------------- @Controller @SessionAttributes("form") @RequestMapping(value = "/sample") public class SampleController { @RequestMapping(method = RequestMethod.GET) public String getCreateForm(Model model) { model.addAttribute("form", new SubAForm()); return "sample/input"; } @RequestMapping(method = RequestMethod.POST) public String register(@ModelAttribute("form") SuperForm form, Model model) { return "sample/input"; } } ------------------------------------------------------- public class SuperForm { private Long superId; public Long getSuperId() { return superId; } public void setSuperId(Long superId) { this.superId = superId; } } ------------------------------------------------------- public class SubAForm extends SuperForm { private Long subAId; public Long getSubAId() { return subAId; } public void setSubAId(Long subAId) { this.subAId = subAId; } } ------------------------------------------------------- <form:form modelAttribute="form" method="post"> <fieldset> <legend>SUPER FIELD</legend> <p> SUPER ID:<form:input path="superId" /> </p> </fieldset> <fieldset> <legend>SUB A FIELD</legend> <p> SUB A ID:<form:input path="subAId" /> </p> </fieldset> <p> <input type="submit" value="register" /> </p> </form:form>

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• Long running method causing race condition

  - by keeleyt83

  Hi, I'm relatively new with hibernate so please be gentle. I'm having an issue with a long running method (~2 min long) and changing the value of a status field on an object stored in the DB. The pseudo-code below should help explain my issue. public foo(thing) { if (thing.getStatus() == "ready") { thing.setStatus("finished"); doSomethingAndTakeALongTime(); } else { // Thing already has a status of finished. Send the user back a message. } } The pseudo-code shouldn't take much explanation. I want doSomethingAndTakeALongTime() to run, but only if it has a status of "ready". My issue arises whenever it takes 2 minutes for doSomethingAndTakeALongTime() to finish and the change to thing's status field doesn't get persisted to the database until it leaves foo(). So another user can put in a request during those 2 minutes and the if statement will evaluate to true. I've already tried updating the field and flushing the session manually, but it didn't seem to work. I'm not sure what to do from here and would appreciate any help. PS: My hibernate session is managed by spring.

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• SQL Structure of DB table with different types of columns

  - by Dmitry Dvornikov

  I have a problem with the optimization of the structure of the database. I'll try to explain it exactly. I create a project, where we can add different values??, but this values must have different types of the columns in the database (eg, int, double , varchar). What is the best way to store the different types of values ??in the database. In the project I'm using Propel 1.6. The point is availability to add value with 'int', 'varchar' and other columns types, to search the table was efficient. In total, I have two ideas. The first is to create a table of "value", which will have columns: "id ", "value_int", "value_double", "value_varchar", etc - with the corresponding column types. Depending on the type of values??, records will be saved with the value in the appropriate column (the rest will be NULL). The second solution is to create separate tables such as "value_int", "value_varchar" etc. There would be columns: "id", "value", which correspond to the relevant types of "value" (ie, such as int, varchar, etc). I must admit that I do not believe any of the above solutions, originally I was thinking about one table "value", where the column would be a "text" type - but this solution would probably be even worse. I would like to know your opinion on this topic, maybe something else would be better. Thanks in advance. EDIT: For example : We have three tables: USER: [table of users] * id * name FIELD: [table of profile fields - where the column 'type' is the type of field, eg int or varchar) * id * type * name VALUE : * id * User_id - ( FK user.id ) * Field_id - ( FK field.id ) * value So we have in each row an user in USER table, and the profile is stored in the VALUE table. Bit each profile field may have a different type (column 'type' in the FIELD table), and based on that I would want this value to add to the appropriate column of the appropriate type.

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• How to calculate the normal of points on a 3D cubic Bézier curve given normals for its start and end points?

  - by Robert

  I'm trying to render a "3D ribbon" using a single 3D cubic Bézier curve to describe it (the width of the ribbon is some constant). The first and last control points have a normal vector associated with them (which are always perpendicular to the tangents at those points, and describe the surface normal of the ribbon at those points), and I'm trying to smoothly interpolate the normal vector over the course of the curve. For example, given a curve which forms the letter 'C', with the first and last control points both having surface normals pointing upwards, the ribbon should start flat, parallel to the ground, slowly turn, and then end flat again, facing the same way as the first control point. To do this "smoothly", it would have to face outwards half-way through the curve. At the moment (for this case), I've only been able to get all the surfaces facing upwards (and not outwards in the middle), which creates an ugly transition in the middle. It's quite hard to explain, I've attached some images below of this example with what it currently looks like (all surfaces facing upwards, sharp flip in the middle) and what it should look like (smooth transition, surfaces slowly rotate round). Silver faces represent the front, black faces the back. Incorrect, what it currently looks like: Correct, what it should look like: All I really need is to be able to calculate this "hybrid normal vector" for any point on the 3D cubic bézier curve, and I can generate the polygons no problem, but I can't work out how to get them to smoothly rotate round as depicted. Completely stuck as to how to proceed!

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• JQuery: how to store records id for data from ajax query in dynamicly created html elements

  - by grapkulec

  Probably question title is rather cryptic but I will try to explain myself here so please bare with me :) Let's assume this configuration: server-side is PHP application responding for requests with data (list of items, single item details, etc.) in json format client-side is JQuery application sending ajax request to that PHP app and creating html content corresponding with received data So, for example: client requests "list of all animals with names staring with 'A'", gets the json response from server, and for every "animal" creates some html gizmo like div with animal description or something like that. It doesn't really matter what html element it will be but it has to point exactly to specific record by "containing" id of that record. And here is my dilemma: is it good solution to use "id" property for that? So it would be like: <div id="10" class="animal"> <p> This is animal of very mysterious kind... </p> </div> <div id="11" class="animal"> <p> And this one is very common to our country... </p> </div> where id="10" is of course indication that this is representation of record with id = 10. Or maybe I should store this record id in some custom made tag like <record_id>10</record_id> and leave an "id" strictly for what it was meant to be (css selector)? I need that record id for further stuff like updating database with some user input or deleting some of "animals" or creating new ones or anything that will be needed. All manipulations will be done with JQuery and ajax requests and responses will be visualized also with dynamic creation of html interface. I'm sure that somebody had to deal with that kind of stuff before so I would be grateful for some tips on that topic.

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• javascript split() array contains

  - by Mahesha999

  While learning JavaScript, I did not get why the output when we print the array returned of the Sting.split() method (with regular expression as an argument) is as explained below. var colorString = "red,blue,green,yellow"; var colors = colorString.split(/[^\,]+/); document.write(colors); //this print 7 times comma: ,,,,,,, However when I print individual element of the array colors, it prints an empty string, three commas and an empty string: document.write(colors[0]); //empty string document.write(colors[1]); //, document.write(colors[2]); //, document.write(colors[3]); //, document.write(colors[4]); //empty string document.write(colors[5]); //undefined document.write(colors[6]); //undefined Then, why printing the array directly gives seven commas. Though I think its correct to have three commas in the second output, I did not get why there is a starting (at index 0) and ending empty string (at index 4). Please explain I am screwed up here.

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• Rails log shows unexpected data as to the time spent on a DB stuff

  - by Arhimed

  I'm running on WinXP + Ruby 1.8.6 + Rails 2.3.5 (frozen to the project) in development environment. Looking at development.log I observe inconsistent data as to the time spent on a database stuff. Example #1 (good): Processing PagesController#index (for 127.0.0.1 at 2010-05-11 12:15:54) [GET] Parameters: {"action"=>"index", "controller"=>"pages"} City Columns (563.0ms) SHOW FIELDS FROM `cities` City Load (15.0ms) SELECT * FROM `cities` WHERE (`cities`.`short_name` = 'NY') LIMIT 1 Redirected to http://xyz:3000/sightings Completed in 953ms (DB: 578) | 302 Found [http://xyz/] Example #2 (unexpected): Processing PagesController#index (for 127.0.0.1 at 2010-05-11 12:15:36) [GET] Parameters: {"action"=>"index", "controller"=>"pages"} City Columns (0.0ms) SHOW FIELDS FROM `cities` City Load (0.0ms) SELECT * FROM `cities` WHERE (`cities`.`short_name` = 'NY') LIMIT 1 Redirected to http://xyz:3000/sightings Completed in 47ms (DB: 32) | 302 Found [http://xyz/] Example #2 shows 32ms were spent on DB while there were just 2 sql querries and both of zero time spent. Example #3 (unexpected): Processing PagesController#index (for 127.0.0.1 at 2010-05-11 11:21:24) [GET] Parameters: {"action"=>"index", "controller"=>"pages"} City Columns (63.0ms) SHOW FIELDS FROM `cities` City Load (62.0ms) SELECT * FROM `cities` WHERE (`cities`.`short_name` = 'NY') LIMIT 1 Redirected to http://xyz:3000/sightings Completed in 1187ms (DB: 297) | 302 Found [http://xyz/] Example #3 shows 297ms while there were querries of 63ms and 62ms (125ms in total). Can't understand it. Could someone explain? Thanks in advance.

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• Help with MySQL query... Need help ordering a group of rows

  - by user156814

  I can tell it best by explaining the query I have, and what I need. I need to be able to get a group of items from the database, grouped by category, manufacturer, and year made. The groupings need to be sorted based on total amount of items within the group. This part is done with the query below. Secondly, I need to be able to show an image of the most expensive item out of the group, which is why I use MAX(items.current_price). I thought MAX() gets the ENTIRE row corresponding to the largest column value. I was wrong, as MAX only gets the numeric value of the largest price. So the query doesnt work well for that. SELECT items.id, items.year, items.manufacturer, COUNT(items.id) AS total, MAX(items.current_price) AS price, items.gallery_url, FROM ebay AS items WHERE items.primary_category_id = 213 AND items.year <> '' AND items.manufacturer <> '' AND items.bad_item <> 1 GROUP BY items.primary_category_id, items.manufacturer, items.year ORDER BY total DESC, price ASC LIMIT 10 if that doesnt explain it well, the results should be something like this id 10548 year 1989 manufacturer bowman total 451 price 8500.00 (The price of the most expensive item in the table/ not the price of item 10548) gallery_url http://ebay.xxxxx (The image of item 10548) A little help please. Thanks

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