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• Really simple JSON serialization in .NET

  - by Evgeny

  I have some simple .NET objects I'd like to serialize to JSON and back again. The set of objects to be serialized is quite small and I control the implementation, so I don't need a generic solution that will work for everything. Since my assembly will be distributed as a library I'd really like to avoid a dependency on some third-party DLL: I just want to give users one assembly that they can reference. I've read the other questions I could find on converting to and from JSON in .NET. The recommended solution of JSON.NET does work, of course, but it requires distributing an extra DLL. I don't need any of the fancy features of JSON.NET. I just need to handle a simple object (or even dictionary) that contains strings, integers, DateTimes and arrays of strings and bytes. On deserializing I'm happy to get back a dictionary - it doesn't need to create the object again. Is there some really simple code out there that I could compile into my assembly to do this simple job? I've also tried System.Web.Script.Serialization.JavaScriptSerializer, but where it falls down is the byte array: I want to base64-encode it and even registering a converter doesn't let me easily accomplish that due to the way that API works (it doesn't pass in the name of the field).

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• R: outlier cleaning for each column in a dataframe by using quantiles 0.05 and 0.95

  - by Rainer

  hi, I am a R-novice. I want to do some outlier cleaning and over-all-scaling from 0 to 1 before putting the sample into a random forest. g<-c(1000,60,50,60,50,40,50,60,70,60,40,70,50,60,50,70,10) If i do a simple scaling from 0 - 1 the result would be: > round((g - min(g))/abs(max(g) - min(g)),1) [1] 1.0 0.1 0.0 0.1 0.0 0.0 0.0 0.1 0.1 0.1 0.0 0.1 0.0 0.1 0.0 0.1 0.0 So my idea is to replace the values of each column that are greater than the 0.95-quantile with the next value smaller than the 0.95-quantile - and the same for the 0.05-quantile. So the pre-scaled result would be: g<-c(**70**,60,50,60,50,40,50,60,70,60,40,70,50,60,50,70,**40**) and scaled: > round((g - min(g))/abs(max(g) - min(g)),1) [1] 1.0 0.7 0.3 0.7 0.3 0.0 0.3 0.7 1.0 0.7 0.0 1.0 0.3 0.7 0.3 1.0 0.0 I need this formula for a whole dataframe, so the functional implementation within R should be something like: > apply(c, 2, function(x) x[x`<quantile(x, 0.95)]`<-max(x[x, ... max without the quantile(x, 0.95)) Can anyone help? Spoken beside: if there exists a function that does this job directly, please let me know. I already checked out cut and cut2. cut fails because of not-unique breaks; cut2 would work, but only gives back string values or the mean value, and I need a numeric vector from 0 - 1. for trial: a<-c(100,6,5,6,5,4,5,6,7,6,4,7,5,6,5,7,1) b<-c(1000,60,50,60,50,40,50,60,70,60,40,70,50,60,50,70,10) c<-cbind(a,b) c<-as.data.frame(c) Regards and thanks for help, Rainer

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• Multiplication of 2 positive numbers giving a negative result

  - by krandiash

  My program is an implementation of a bloom filter. However, when I'm storing my hash function results in the bit array, the function (of the form f(i) = (a*i + b) % m where a,b,i,m are all positive integers) is giving me a negative result. The problem seems to be in the calculation of a*i which is coming out to be negative. Ignore the print statements in the code; those were for debugging. Basically, the value of temp in this block of code is coming out to be negative and so I'm getting an ArrayOutOfBoundsException. m is the bit array length, z is the number of hash functions being used, S is the set of values which are members of this bloom filter and H stores the values of a and b for the hash functions f1, f2, ..., fz. public static int[] makeBitArray(int m, int z, ArrayList<Integer> S, int[] H) { int[] C = new int[m]; for (int i = 0; i < z; i++) { for (int q = 0; q < S.size() ; q++) { System.out.println(H[2*i]); int temp = S.get(q)*(H[2*i]); System.out.println(temp); System.out.println(S.get(q)); System.out.println(H[2*i + 1]); System.out.println(m); int t = ((H[2*i]*S.get(q)) + H[2*i + 1])%m; System.out.println(t); C[t] = 1; } } return C; } Any help is appreciated.

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• How to cache an HTTP POST response?

  - by KARASZI István

  I would like to create a cacheable HTTP response for a POST request. My actual implementation responses the following for the POST request: HTTP/1.1 201 Created Expires: Sat, 03 Oct 2020 15:33:00 GMT Cache-Control: private,max-age=315360000,no-transform Content-Type: application/x-www-form-urlencoded; charset=UTF-8 Content-Length: 9 ETag: 2120507660800737950 Last-Modified: Wed, 06 Oct 2010 15:33:00 GMT ......... But it looks like that the browsers (Safari, Firefox tested) are not cacheing the response. In the HTTP RFC the corresponding part says: Responses to this method are not cacheable, unless the response includes appropriate Cache-Control or Expires header fields. However, the 303 (See Other) response can be used to direct the user agent to retrieve a cacheable resource. So I think it should be cached. I know I could set a session variable and set a cookie and do a 303 redirect, but I want to cache the response of the POST request. Is there any way to do this? P.S.: I've started with a simple 200 OK, so it does not work. Thanks,

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• Polymorphic Queue

  - by metdos

  Hello Everyone, I'm trying to implement a Polymorphic Queue. Here is my trial: QQueue <Request *> requests; while(...) { QString line = QString::fromUtf8(client->readLine()).trimmed(); if(...)){ Request *request=new Request(); request->tcpMessage=line.toUtf8(); request->decodeFromTcpMessage(); //this initialize variables in request using tcpMessage if(request->requestType==REQUEST_LOGIN){ LoginRequest loginRequest; request=&loginRequest; request->tcpMessage=line.toUtf8(); request->decodeFromTcpMessage(); requests.enqueue(request); } //Here pointers in "requests" do not point to objects I created above, and I noticed that their destructors are also called. LoginRequest *loginRequest2=dynamic_cast<LoginRequest *>(requests.dequeue()); loginRequest2->decodeFromTcpMessage(); } } Unfortunately, I could not manage to make work Polymorphic Queue with this code because of the reason I mentioned in second comment.I guess, I need to use smart-pointers, but how? I'm open to any improvement of my code or a new implementation of polymorphic queue. Thanks.

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• Strange constructor

  - by Bilthon

  Well, I'm gonna be pretty straightforward here, I just have a piece of code in c++ which I'm not sure I really understand and need some help with. Ok, to simplify lets just say I have a class that is defined like this: (the real class is a little bit more complicated, but this is what matters) class myClass : public Runnable { Semaphore *m_pMySemaphore; __Queue<Requests> *m_pQueue; Request m_Request; VetorSlotBuffer *m_vetorSlotBuffer; } Up to here nothing is wrong, myClass is just a regular class which has 3 members that actually are pointers to other classes and an object of the class Request, the implementation of those classes not being important for my point here. Then when this person implemented the constructor for myClass he or she did this: myClass::myClass() : m_pMySemaphore(0), m_pQueue(0), m_vetorSlotBuffer(0) { } It's pretty evident that those three variables are treated like that by the constructor because they are pointers, am I right? but what kind of syntax is that? am I setting the pointers to null by doing that? I've seen a little bit of c++ already but never found something like that. And secondly, what's the deal with the ":" after the constructor declaration? that I've seen but never took the time to investigate. Is this like an inner class or something? Thank you very much in advance. Nelson R. Perez

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• Why does the following Toggle function perform four different operations instead of two?

  - by marcamillion

  You can see the implementation here: http://jsfiddle.net/BMWZd/8/ What I am trying to do, when you click on 'John Brown', you see the first element at top turn black. When you click it again, the border of the dotted circle disappears, then when you click 'John Brown' again, you see something else, then finally once again it all disappears. What I am trying to achieve is when you click it once, everything turns black (like it does now), then you click it again, everything disappears and goes back to the original state. Important distinction, what I mean is...when one of the names in the box are not clicked. So if you clicked John Brown then moved to Jack Dorsey, the #1 at top should stay black. But if you were to click Jack Dorsey again, i.e. you 'unclicked' it, then it should disappear. Also, how do I tighten it up, so that it responds quicker. Now when you click it, it feels like there is a little bit of a lag between when it was clicked and when it responds. Edit1: If anyone is interested...the UI that this will be used in is for my webapp - http://www.compversions.com

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• Multiple threads modifying a collection in Java??

  - by posdef

  Hi, The project I am working on requires a whole bunch of queries towards a database. In principle there are two types of queries I am using: read from excel file, check for a couple of parameters and do a query for hits in the database. These hits are then registered as a series of custom classes. Any hit may (and most likely will) occur more than once so this part of the code checks and updates the occurrence in a custom list implementation that extends ArrayList. for each hit found, do a detail query and parse the output, so that the classes created in (I) get detailed info. I figured I would use multiple threads to optimize time-wise. However I can't really come up with a good way to solve the problem that occurs with the collection these items are stored in. To elaborate a little bit; throughout the execution objects are supposed to be modified by both (I) and (II). I deliberately didn't c/p any code, as it would be big chunks of code to make any sense.. I hope it make some sense with the description above. Thanks,

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• jQuery Validation plugin results in empty AJAX POST

  - by user305412

  Hi, I have tried to solve this issue for at couple of days with no luck. I have a form, where I use the validation plugin, and when I try to submit it, it submits empty vars. Now, if I remove the validation, everything works fine. Here is my implementation: $(document).ready(function(){ $("#myForm").validate({ rules: { field1: { required: true, minlength: 5 }, field2: { required: true, minlength: 10 } }, messages: { field1: "this is required", field2: "this is required", }, errorLabelContainer: $("#validate_msg"), invalidHandler: function(e, validator) { var errors = validator.numberOfInvalids(); if (errors) { $("#validate_div").show(); } }, onkeyup: false, success: false, submitHandler: function(form) { doAjaxPost(form); } }); }); function doAjaxPost(form) { // do some stuff $(form).ajaxSubmit(); return false; } As I wrote this does not work when I have my validation, BUT if I remove that, and just add an onsubmit="doAjaxPost(this.form); return false"; to my HTML form, it works - any clue??? Now here is the funny thing, everything works as it should in Safari, but not in firefox 3.6.2 (Mac OS X)!

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• cocoa hello world screensaver

  - by RW

  I have been studying NSView and as such I thought I would give a shot at a screen saver. I have been able to display and image in an NSView but I can't seen to modify this example code to display a simple picture in ScreenSaverView. http://www.mactech.com/articles/mactech/Vol.20/20.06/ScreenSaversInCocoa/ BTW great tutorial that works with Snow Leopard. I would think to simply display an image I would need something that looked like this... What am I doing wrong? // // try_screensaverView.m // try screensaver // #import "try_screensaverView.h" @implementation try_screensaverView - (id)initWithFrame:(NSRect)frame isPreview:(BOOL)isPreview { self = [super initWithFrame:frame isPreview:isPreview]; if (self) { [self setAnimationTimeInterval:1]; //refresh once per sec } return self; } - (void)startAnimation { [super startAnimation]; NSString *path = [[NSBundle mainBundle] pathForResource:@"leaf" ofType:@"JPG" inDirectory:@""]; image = [[NSImage alloc] initWithContentsOfFile:path]; } - (void)stopAnimation { [super stopAnimation]; } - (void)drawRect:(NSRect)rect { [super drawRect:rect]; } - (void)animateOneFrame { ////////////////////////////////////////////////////////// //load image and display This does not scale the image NSRect bounds = [self bounds]; NSSize newSize; newSize.width = bounds.size.width; newSize.height = bounds.size.height; [image setSize:newSize]; NSRect imageRect; imageRect.origin = NSZeroPoint; imageRect.size = [image size]; NSRect drawingRect = imageRect; [image drawInRect:drawingRect fromRect:imageRect operation:NSCompositeSourceOver fraction:1]; } - (BOOL)hasConfigureSheet { return NO; } - (NSWindow*)configureSheet { return nil; } @end

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• Best way to split a string by word (SQL Batch separator)

  - by Paul Kohler

  I have a class I use to "split" a string of SQL commands by a batch separator - e.g. "GO" - into a list of SQL commands that are run in turn etc. ... private static IEnumerable<string> SplitByBatchIndecator(string script, string batchIndicator) { string pattern = string.Concat("^\\s*", batchIndicator, "\\s*$"); RegexOptions options = RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.Multiline; foreach (string batch in Regex.Split(script, pattern, options)) { yield return batch.Trim(); } } My current implementation uses a Regex with yield but I am not sure if it's the "best" way. It should be quick It should handle large strings (I have some scripts that are 10mb in size for example) The hardest part (that the above code currently does not do) is to take quoted text into account Currently the following SQL will incorrectly get split: var batch = QueryBatch.Parse(@"-- issue... insert into table (name, desc) values('foo', 'if the go is on a line by itself we have a problem...')"); Assert.That(batch.Queries.Count, Is.EqualTo(1), "This fails for now..."); I have thought about a token based parser that tracks the state of the open closed quotes but am not sure if Regex will do it. Any ideas!?

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• Generate an ID via COM interop

  - by Erik van Brakel

  At the moment, we've got an unmaintanable ball of code which offers an interface to a third party application. The third party application has a COM assembly which MUST be used to create new entries. This process involves two steps: generate a new object (basically an ID), and update that object with new field values. Because COM interop is so slow, we only use that to generate the ID (and related objects) in the database. The actual update is done using a regular SQL query. What I am trying to figure out if it's possible to use NHibernate to do some of the heavy lifting for us, without bypassing the COM assembly. Here's the code for saving something to the database as I envision it: using(var s = sessionFactory.OpenSession()) using(var t = s.BeginTransaction()) { MyEntity entity = new MyEntity(); s.Save(entity); t.Commit(); } Regular NH code I'd say. Now, this is where it gets tricky. I think I have to supply my own implementation of NHibernate.Id.IIdentifierGenerator which calls the COM assembly in the Generate method. That's not a problem. What IS a problem is that the COM assembly requires initialisation, which does take a bit of time. It also doesn't like multiple instances in the same process, for some reason. What I would like to know is if there's a way to properly access an external service in the generator code. I'm free to use any technique I want, so if it involves something like an IoC container that's no problem. The thing I am looking for is where exactly to hook-up my code so I can access the things I need in my generator, without having to resort to using singletons or other nasty stuff.

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• segfault during __cxa_allocate_exception in SWIG wrapped library

  - by lefticus

  While developing a SWIG wrapped C++ library for Ruby, we came across an unexplained crash during exception handling inside the C++ code. I'm not sure of the specific circumstances to recreate the issue, but it happened first during a call to std::uncaught_exception, then after a some code changes, moved to __cxa_allocate_exception during exception construction. Neither GDB nor valgrind provided any insight into the cause of the crash. I've found several references to similar problems, including: http://wiki.fifengine.de/Segfault_in_cxa_allocate_exception http://forums.fifengine.de/index.php?topic=30.0 http://code.google.com/p/osgswig/issues/detail?id=17 https://bugs.launchpad.net/ubuntu/+source/libavg/+bug/241808 The overriding theme seems to be a combination of circumstances: A C application is linked to more than one C++ library More than one version of libstdc++ was used during compilation Generally the second version of C++ used comes from a binary-only implementation of libGL The problem does not occur when linking your library with a C++ application, only with a C application The "solution" is to explicitly link your library with libstdc++ and possibly also with libGL, forcing the order of linking. After trying many combinations with my code, the only solution that I found that works is the LD_PRELOAD="libGL.so libstdc++.so.6" ruby scriptname option. That is, none of the compile-time linking solutions made any difference. My understanding of the issue is that the C++ runtime is not being properly initialized. By forcing the order of linking you bootstrap the initialization process and it works. The problem occurs only with C applications calling C++ libraries because the C application is not itself linking to libstdc++ and is not initializing the C++ runtime. Because using SWIG (or boost::python) is a common way of calling a C++ library from a C application, that is why SWIG often comes up when researching the problem. Is anyone out there able to give more insight into this problem? Is there an actual solution or do only workarounds exist? Thanks.

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• Possible defect with jQuery ':checked' selector (finding checked checkbox when there are none)

  - by Mphammad Ashour

  Found a strange thing. The following code is supposed to set a default value for a UI element based on whether one of a group of checkboxes (all having attribute name="privacy") is checked (in say, a form postback). If there is no value in the HTML sent by the server (the form is not a postback), the default value should be firstMenuItemKey. Otherwise, it should be the one checked in the underlying HTML. However, while this works on the first call to the URL that includes the form, a refresh of the page will set the value of defaultPrivacyValue to one of the privacy checkboxes'. I've checked that the server isn't checking the checkbox before the script runs (it's not). I've also checked whether somewhere else in the script is checking the checkbox (it's not). var defaultPrivacyValue = firstMenuItemKey; $('input[name=privacy]:checked').each(function() { defaultPrivacyValue = $(this).next().find('.name').text(); }); selectMenuItem(defaultPrivacyValue); When I chaged the selector to 'input[name=privacy][checked=checked]' it worked as expected. Is this a defect in the jQuery implementation of DOM retrieval based on the ':checked' selector???? I'm using jQuery 1.4.2. Thanks for any help you can give.

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• PayPal integration woes: PDT hangs on return to site

  - by Tom

  Hi, I'm implementing PayPal IPN & PDT. After some headache & time at the sandbox, IPN is working well and PDT returns the correct $_GET data. The implementation is as follows: Pass user ID in form to PayPal User buys product and triggers IPN which updates database for given user ID PDT returns transaction ID when user returns to site The return page says "please wait" and repeat-Ajax-checks for the transaction status User is redirected to success/failure page Everything works well, EXCEPT that when using the PayPal ready PHP code for PDT to do a return POST, the page hangs. PayPal waits for a response and the user never gets back to my site. I'm not getting a fail status, just nothing. The funny thing is that once the unknown error occurs, my test domain becomes unresponsive for a short period. The code (PHP): https://www.paypal.com/us/cgi-bin/webscr?cmd=p/xcl/rec/pdt-code-outside If I comment out the POST back, it all works fine. I'm able to pin down the problem to once the code enters the while{} loop. Unfortunately, I'm not experienced enough to write a replacement from scratch for the PayPal code, so would really appreciate any ideas on what might be wrong. The POST back goes to ssl://www.sandbox.paypal.com, and I'm using button code and an authorisation token that have all been created via a sandbox test account. Thanks in advance.

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• Subclassing UIButton but can't access my properties

  - by Ross Ellerington

  Hi, I've created a sub class of UIButton: // // DetailButton.h #import <Foundation/Foundation.h> #import <MapKit/MapKit.h> @interface MyDetailButton : UIButton { NSObject *annotation; } @property (nonatomic, retain) NSObject *annotation; @end // // DetailButton.m // #import "MyDetailButton.h" @implementation MyDetailButton @synthesize annotation; @end I figured that I can then create this object and set the annotation object by doing the following: MyDetailButton* rightButton = [MyDetailButton buttonWithType:UIButtonTypeDetailDisclosure]; rightButton.annotation = localAnnotation; localAnnotation is an NSObject but it is really an MKAnnotation. I can't see why this doesn't work but at runtime I get this error: 2010-05-27 10:37:29.214 DonorMapProto1[5241:207] *** -[UIButton annotation]: unrecognized selector sent to instance 0x445a190 2010-05-27 10:37:29.215 DonorMapProto1[5241:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[UIButton annotation]: unrecognized selector sent to instance 0x445a190' ' I can't see why it's even looking at UIButton because I've subclassed that so it should be looking at the MyDetailButton class to set that annotation property. Have I missed something really obvious. It feels like it :) Thanks in advance for any help you can provide Ross

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• Umlaute from JSP-page are misinterpreted

  - by Karin

  I'm getting Input from a JSP page, that can contain Umlaute. (e.g. Ä,Ö,Ü,ä,ö,ü,ß). Whenever an Umlaut is entered in the Input field an incorrect value gets passed on. e.g. If an "ä" (UTF-8:U+00E4) gets entered in the input field, the String that is extracted from the argument is "ä" (UTF-8: U+00C3 and U+00A4) It seems to me as if the UTF-8 hex encoding (which is c3 a4 for an "ä") gets used for the conversion. How can I retrieved the correct value? Here are snippets from the current implementation The JSP-page passes the input value "pk" on to the processing logic: <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> ... <input type="text" name="<%=pk.toString()%>" value="<%=value%>" size="70"/> <button type="submit" title="Edit" value='Save' onclick="action.value='doSave';pk.value='<%=pk.toString()%>'"><img src="icons/run.png"/>Save</button> The value gets retrieved from args and converted to a string: UUID pk = UUID.fromString(args.get("pk")); //$NON-NLS-1$ String value = args.get(pk.toString()); Note: Umlaute that are saved in the Database get displayed correctly on the page.

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• Implementing Model-level caching

  - by Byron

  I was posting some comments in a related question about MVC caching and some questions about actual implementation came up. How does one implement a Model-level cache that works transparently without the developer needing to manually cache, yet still remains efficient? I would keep my caching responsibilities firmly within the model. It is none of the controller's or view's business where the model is getting data. All they care about is that when data is requested, data is provided - this is how the MVC paradigm is supposed to work. (Source: Post by Jarrod) The reason I am skeptical is because caching should usually not be done unless there is a real need, and shouldn't be done for things like search results. So somehow the Model itself has to know whether or not the SELECT statement being issued to it worthy of being cached. Wouldn't the Model have to be astronomically smart, and/or store statistics of what is being most often queried over a long period of time in order to accurately make a decision? And wouldn't the overhead of all this make the caching useless anyway? Also, how would you uniquely identify a query from another query (or more accurately, a resultset from another resultset)? What about if you're using prepared statements, with only the parameters changing according to user input? Another poster said this: I would suggest using the md5 hash of your query combined with a serialized version of your input arguments. This would require twice the number of serialization options. I was under the impression that serialization was quite expensive, and for large inputs this might be even worse than just re-querying. And is the minuscule chance of collision worth worrying about? Conceptually, caching in the Model seems like a good idea to me, but it seems in practicality the developer should have direct control over caching and write it into the controller. Thoughts/ideas? Edit: I'm using PHP and MySQL if that helps to narrow your focus.

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• cookie name is truncated in Servlet 3.0 HttpServletRequest (Glassfish V3)

  - by idplmal

  I'm porting our Web authentication/authorization middleware for use in containers implementing the new servlet 3.0 API (Glassfish V3 in this case). The middleware pulls cookies from the HttpServletRequest filtering on cookies with names of the form "DACS:FEDERATION::JURISDICTION:username". This works fine in the version 2.5 servlet API but is broken in 3.0. The cookie names in 3.0 are being truncated at the first ":" in the name. I understand that the servlet 3.0 implementation defaults to RFC 2109 cookies which are more restrictive about cookie names than the old Netscape spec (":" is among the characters not allowed in RFC 2109 cookie names). Digging into the servlet 3.0 source code, it appears that the use of RFC2109 names can be disabled by setting a System property "org.glassfish.web.rfc2109.cookie_names_enforced" to false. I've tried this to no avail. But besides that, the code that uses checks cookie names is in the constructor for Cookie, and it would appear that the truncation is occurring elsewhere. So - finally - the question. Have others bumped into such issues in the servlet 3.0 API and have you found a work around?

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• Generating lognormally distributed random number from mean, coeff of variation

  - by Richie Cotton

  Most functions for generating lognormally distributed random numbers take the mean and standard deviation of the associated normal distribution as parameters. My problem is that I only know the mean and the coefficient of variation of the lognormal distribution. It is reasonably straight forward to derive the parameters I need for the standard functions from what I have: If mu and sigma are the mean and standard deviation of the associated normal distribution, we know that coeffOfVar^2 = variance / mean^2 = (exp(sigma^2) - 1) * exp(2*mu + sigma^2) / exp(mu + sigma^2/2)^2 = exp(sigma^2) - 1 We can rearrange this to sigma = sqrt(log(coeffOfVar^2 + 1)) We also know that mean = exp(mu + sigma^2/2) This rearranges to mu = log(mean) - sigma^2/2 Here's my R implementation rlnorm0 <- function(mean, coeffOfVar, n = 1e6) { sigma <- sqrt(log(coeffOfVar^2 + 1)) mu <- log(mean) - sigma^2 / 2 rlnorm(n, mu, sigma) } It works okay for small coefficients of variation r1 <- rlnorm0(2, 0.5) mean(r1) # 2.000095 sd(r1) / mean(r1) # 0.4998437 But not for larger values r2 <- rlnorm0(2, 50) mean(r2) # 2.048509 sd(r2) / mean(r2) # 68.55871 To check that it wasn't an R-specific issue, I reimplemented it in MATLAB. (Uses stats toolbox.) function y = lognrnd0(mean, coeffOfVar, sizeOut) if nargin < 3 || isempty(sizeOut) sizeOut = [1e6 1]; end sigma = sqrt(log(coeffOfVar.^2 + 1)); mu = log(mean) - sigma.^2 ./ 2; y = lognrnd(mu, sigma, sizeOut); end r1 = lognrnd0(2, 0.5); mean(r1) % 2.0013 std(r1) ./ mean(r1) % 0.5008 r2 = lognrnd0(2, 50); mean(r2) % 1.9611 std(r2) ./ mean(r2) % 22.61 Same problem. The question is, why is this happening? Is it just that the standard deviation is not robust when the variation is that wide? Or have a screwed up somewhere?

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• Eclipse won't believe I have Maven 2.2.1

  - by Andrew Clegg

  I have a project (built from an AppFuse template) that requires Maven 2.2.1. So I upgraded to this (from 2.1.0) and set my path and my M2_HOME and MAVEN_HOME env variables. Then I ran mvn eclipse:eclipse and imported the project into Eclipse (Galileo). However, in the problems list for the project (and at the top of the pom.xml GUI editor) it says: Unable to build project '/export/people/clegg/data/GanymedeWorkspace/funcserve/pom.xml; it requires Maven version 2.2.1 (Please ignore 'GanymedeWorkspace', I really am using Galileo!) This persists whether I set Eclipse to use its Embedded Maven implementation, or the external 2.2.1 installation, in the Preferences - Maven - Installations dialog. I've tried closing and reopening the project, reindexing the repository, cleaning the project, restarting the IDE, logging out and back in again, everything I can think of! But Eclipse still won't believe I have Maven 2.2.1. I just did a plugin update so I have the latest version of Maven Integration for Eclipse -- 0.9.8.200905041414. Does anyone know how to convince Eclipse I really do have the right version of Maven? It's like it's recorded the previous version somewhere else and won't pay any attention to my changes :-( Many thanks! Andrew.

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• Suggestions of the easiest algorithms for some Graph operations

  - by Nazgulled

  Hi, The deadline for this project is closing in very quickly and I don't have much time to deal with what it's left. So, instead of looking for the best (and probably more complicated/time consuming) algorithms, I'm looking for the easiest algorithms to implement a few operations on a Graph structure. The operations I'll need to do is as follows: List all users in the graph network given a distance X List all users in the graph network given a distance X and the type of relation Calculate the shortest path between 2 users on the graph network given a type of relation Calculate the maximum distance between 2 users on the graph network Calculate the most distant connected users on the graph network A few notes about my Graph implementation: The edge node has 2 properties, one is of type char and another int. They represent the type of relation and weight, respectively. The Graph is implemented with linked lists, for both the vertices and edges. I mean, each vertex points to the next one and each vertex also points to the head of a different linked list, the edges for that specific vertex. What I know about what I need to do: I don't know if this is the easiest as I said above, but for the shortest path between 2 users, I believe the Dijkstra algorithm is what people seem to recommend pretty often so I think I'm going with that. I've been searching and searching and I'm finding it hard to implement this algorithm, does anyone know of any tutorial or something easy to understand so I can implement this algorithm myself? If possible, with C source code examples, it would help a lot. I see many examples with math notations but that just confuses me even more. Do you think it would help if I "converted" the graph to an adjacency matrix to represent the links weight and relation type? Would it be easier to perform the algorithm on that instead of the linked lists? I could easily implement a function to do that conversion when needed. I'm saying this because I got the feeling it would be easier after reading a couple of pages about the subject, but I could be wrong. I don't have any ideas about the other 4 operations, suggestions?

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• iPhone: Creating a hierarchy-based table navigation.

  - by Jack Griffiths

  Hi there, I've tried to ask this before, but nothing got answered. Basically, I would like someone to explain to me how to create a table, which when a cell is tapped, pushes the user to the next view for that cell. I have this so far: Click here to view what I have. I would further like to, say when CSS is tapped, it goes to a new view which has another table in it. This table would then take the user to a detail view, which is scrollable and you can switch pages through it. I would appreciate longer, more structured tutorials on how to do each and every bit to get it to work. Here's my array in my implementation file: - (void)viewDidLoad { arryClientSide = [[NSArray alloc] initWithObjects:@"CSS", @"HTML", @"JavaScript", @"XML", nil]; arryServerSide = [[NSArray alloc] initWithObjects:@"Apache", @"PHP", @"SQL", nil]; self.title = @"Select a Language"; [super viewDidLoad]; } and my .h: @interface RootViewController : UITableViewController <UITableViewDelegate, UITableViewDataSource> { IBOutlet UITableView *tblSimpleTable; NSArray *arryClientSide; NSArray *arryServerSide; } My current code crashes the script, and this error is returned in the console: Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '-[UITableViewController loadView] loaded the "NextView" nib but didn't get a UITableView.' If that error is the source of why it's not pushing, then an explanation of how to remedy that would also be appreciated Many thanks, Jack

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• Problem with TTWebController… alternative view controller template for UIWebView?

  - by prendio2

  I have a UIWebView with content populated from a Last.fm API call. This content contains links, many of which are handled by parsing info from the URL in: - (BOOL)webView:(UIWebView *)aWbView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType; …and passing that info on to appropraite view controllers. When I cannot handle a URL I would like to push a new view controller on the stack and load the webpage into a UIWebView there. The TTWebController in Three20 looks very promising since it has also implemented a navigation toolbar, loading indicators etc. Somewhat naively perhaps I thought I would be able to use this controller to display web content in my app, without implementing Three20 throughout the app. I followed the instructions on github to add Three20 to my project and added the following code to deal with URLs in shouldStartLoadWithRequest: TTWebController* browser = [[TTWebController alloc]init]; [browser openURL:@"http://three20.info"]; //initially test with this URL [self.navigationController pushViewController:navigator animated:YES]; This crashes my app however with the following notice: *** -[TTNavigator setParentViewController:]: unrecognized selector sent to instance 0x3d5db70 What else do I need to do to implement the TTWebController in my app? Or do you know of an alternative view controller template that I can use instead of the Three20 implementation?

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• Is there a fast alternative to creating a Texture2D from a Bitmap object in XNA?

  - by Matthew Bowen

  I've looked around a lot and the only methods I've found for creating a Texture2D from a Bitmap are: using (MemoryStream s = new MemoryStream()) { bmp.Save(s, System.Drawing.Imaging.ImageFormat.Png); s.Seek(0, SeekOrigin.Begin); Texture2D tx = Texture2D.FromFile(device, s); } and Texture2D tx = new Texture2D(device, bmp.Width, bmp.Height, 0, TextureUsage.None, SurfaceFormat.Color); tx.SetData<byte>(rgbValues, 0, rgbValues.Length, SetDataOptions.NoOverwrite); Where rgbValues is a byte array containing the bitmap's pixel data in 32-bit ARGB format. My question is, are there any faster approaches that I can try? I am writing a map editor which has to read in custom-format images (map tiles) and convert them into Texture2D textures to display. The previous version of the editor, which was a C++ implementation, converted the images first into bitmaps and then into textures to be drawn using DirectX. I have attempted the same approach here, however both of the above approaches are significantly too slow. To load into memory all of the textures required for a map takes for the first approach ~250 seconds and for the second approach ~110 seconds on a reasonable spec computer. If there is a method to edit the data of a texture directly (such as with the Bitmap class's LockBits method) then I would be able to convert the custom-format images straight into a Texture2D and hopefully save processing time. Any help would be very much appreciated. Thanks

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