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• Data frame linear fit in R

  - by user1247384

  This is perhaps a simple question, but I am n00b.Say I have a data frame with a bunch of columns. I need to call lm function over the column 1 and 2, 1 and 3, and so on. So basically I need to loop over all columns and store the results of the fit as I build the model. The problem I am running into is that lm(df[1]~df[2], data = df) doesnt work. In this case df is the data frame object and df[1] is the first column. What is a good way to do this in a loop, as in access the columns of df in an iterative fashion. Thanks.

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• Broken if statement

  - by Vladimir Nani

  Maybe I am crazy but how that could be? some == null is always false but debugger goes into if-statement body anyway. Any ideas? I have restarted visual studio I have cleaned every bin/obj folder It is not the case that i don`t understand that WindowsIdentity.GetCurrent() may return null. That was my first idea. var some = new object(); if (some == null) { throw new Exception("hi!"); } else { do(); } My code: private void GetCurrentWindowsIdentity() { var identity = WindowsIdentity.GetCurrent() if (identity == null) { throw new Exception(Errors.IdentityIsNullException); } try { if (CurrentAuthenticationWrapper.AuthenticationType == AuthenticationType.Windows) { CurrentLogin = _identity != null ? _identity.Name : string.Empty; } } catch (Exception ex) { ViewManager.ShowError(ex); } _identity = identity; }

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• How to handle Foreign key for optional field in .NET

  - by brz dot net

  What is the best way to handle following situation? A dropdown(for master table) is optional in a particular form. But, In database table the field is constrained with foreign key. If user don't select from dropdown then It creates problem because of foreign key. One solution is to create default option in master table and use it in case of blank selection. but in dropdown, we need to handle this to show on top. Is it perfect solution? Is there any other optimized solution for this? Thanks

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• Does introducing foreign keys to MySQL reduce performance

  - by Tam

  I'm building Ruby on Rails 2.3.5 app. By default, Ruby on Rails doesn't provide foreign key contraints so I have to do it manually. I was wondering if introducing foreign keys reduces query performance on the database side enough to make it not worth doing. Performance in this case is my first priority as I can check for data consistency with code. What is your recommendation in general? do you recommend using foreign keys? and how do you suggest I should measure this?

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• How to access a XML file in a maven project so it stays available when packaged

  - by Manuel

  I currently started working on a maven web-app project that needs to be launched with the jetty:run-exploded goal for development/debugging in eclipse. Now, I have an XML file which contents I need to access at runtime. My problem is: where to put the file so that the code that does the reading works both in "exploded" and packaged (i.e. in the WAR) mode? Putting the file in src/main/java (so as to be in the classpath) won't cut it since maven filters out all non-java files on packaging. When the file is in src/main/resources, one mean would be to figure out the root path of the project (during eclipse development) and look into that directory - but this won't be the case anymore when the project will be packaged. Of course I could go into writing code that tries to read the file from both locations, but this seems rather cumbersome. Any suggestions?

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• Confusions with CSS and JavaScript relations ?

  - by Anil Namde

  I have table cell which has class "cellActive". Which has following defination .cellActive{background:"#DDDDDD"} Now i am trying to read the background color property for the cell and it comes null/"". var bgColor = cell.style.backgroundColor; // returning "" Is that something mistake on my part of its by behavior. If CSS class is assigning CSS to element can't we read its value in JS ? Does this mean that if we are not assigning property directly to the element we cant get it if in case its inheriting it ?

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• How to refactor this Ruby on Rails code?

  - by yuval

  I want to fetch posts based on their status, so I have this code inside my PostsController index action. It seems to be cluttering the index action, though, and I'm not sure it belongs here. How could I make it more concise and where would I move it in my application so it doesn't clutter up my index action (if that is the correct thing to do)? if params[:status].empty? status = 'active' else status = ['active', 'deleted', 'commented'].include?(params[:status]) ? params[:status] : 'active' end case status when 'active' #active posts are not marked as deleted and have no comments is_deleted = false comments_count_sign = "=" when 'deleted' #deleted posts are marked as deleted and have no comments is_deleted = true comments_count_sign = "=" when 'commented' #commented posts are not marked as deleted and do have comments is_deleted = false comments_count_sign = ">" end @posts = Post.find(:all, :conditions => ["is_deleted = ? and comments_count_sign #{comments_count_sign} 0", is_deleted])

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• Safe to cast pointer to a forward-declared class to its true base class in C++?

  - by Matt DiMeo

  In one header file I have: #include "BaseClass.h" // a forward declaration of DerivedClass, which extends class BaseClass. class DerivedClass ; class Foo { DerivedClass *derived ; void someMethod() { // this is the cast I'm worried about. ((BaseClass*)derived)->baseClassMethod() ; } }; Now, DerivedClass is (in its own header file) derived from BaseClass, but the compiler doesn't know that at the time it's reading the definition above for class Foo. However, Foo refers to DerivedClass pointers and DerivedClass refers to Foo pointers, so they can't both know each other's declaration. First question is whether it's safe (according to C++ spec, not in any given compiler) to cast a derived class pointer to its base class pointer type in the absence of a full definition of the derived class. Second question is whether there's a better approach. I'm aware I could move someMethod()'s body out of the class definition, but in this case it's important that it be inlined (part of an actual, measured hotspot - I'm not guessing).

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• Treating a fat webservice in .net 3.5 c#

  - by Chris M

  I'm dealing with an obese 3rd party webservice that returns about 3mb of data for a simple search results, about 50% of the data in that response is junk. Would it make sense then to remap this data to my own result object and ditch the response so I'm storing 1-2 mb in memory for filtering and sorting rather than using the web-responses own object and using 2-4 or am I missing a point? So far I've been accessing the webservice from a separate project and using a new class to provide the interaction and to handle the persistence so my project looks like this |- Web (mvc2 proj) |- DAL (database/storage fluent-nhibernate) |- SVCGateway (interaction layer + webservice related models) |- Services -------------- |- Tests |- Specs I'm trying to make the application behave fast and I also need to store the result set temporarily in case a customer goes to view the product and wants to go back to the results. (Service returns only 500 of possible 14K results). So basically I'm looking for confirmation that I'm doing the right thing in pushing the results into my own objects or if I'm breaking some rule or even if there's a better way of handling it. Thanks

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• Sending bulk notification emails without blocking

  - by FreshCode

  For my client's custom-built CRM, I want users (technicians) to be notified of changes to marked cases via email. This warrants a simple subscription mapping table between users and cases and automated emails to be sent every time a change is made to a case from within the logging method. How do I send 10-100 emails to subscribed users without bogging down my logging method? My SMTP server is on a peer on my LAN, so sends should be quick, but ideally this should be handled by an external queuing process. I can have a cron job send any outstanding emails every 10 minutes, but for this specific client cases are quite time-sensitive and instant notification (as instant as email can be) would be great. How can I send bulk notification emails from within ASP.NET MVC without bogging down my logging method?

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• Java - Unknown characters passing as [a-zA-z0-9]*?

  - by Twodordan

  Hello, I'm no expert in regex but I need to parse some input I have no control over, and make sure I filter away any strings that don't have A-z and/or 0-9. When I run this, Pattern p = Pattern.compile("^[a-zA-Z0-9]*$"); //fixed typo if(!p.matcher(gottenData).matches()) System.out.println(someData); //someData contains gottenData certain spaces + an unknown symbol somehow slip through the filter (gottenData is the red rectangle): In case you're wondering, it DOES also display Text, it's not all like that. For now, I don't mind the [?] as long as it also contains some string along with it. Please help. [EDIT] as far as I can tell from the (very large) input, the [?]'s are either white spaces either nothing at all; maybe there's some sort of encoding issue, also perhaps something to do with #text nodes (input is xml)

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• How to write following MongoDB query in C# Driver?

  - by user3043457

  I wrote the exact query I need in Mongo console, but I'm having trouble rewriting it in C# driver. Here's a sample of the document, it's simple dictionary: { "_id" : ObjectId("539716bc101c588f941e2c27"), "_t" : "DictionaryDocument", "CsvSeparator" : ",", "SelectedAccounts" : "0", ... } Here's the query: db.settings.find({"SelectedAccounts" :{$exists:true}},{"SelectedAccounts":1, "_id":0} ) Now, I got the first part, Find with exists working, but how to write the second parameter in C# driver? I'd just like a single string as a result, not entire document. Here's C# code I got so far: _collection.FindOneAs(typeof(DictionaryDocument), Query.Exists(key)); key in this case is "SelectedAccounts". I'd like the query to filter and return only the data I need, I don't want to return all the results and search on the C# side. EDIT: I wouldn't mind if _id was passed back, but I don't need it. So only this part would work if it could be converted in C#: db.settings.find({"SelectedAccounts" :{$exists:true}},{"SelectedAccounts":1} )

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• Conditional SELECT MySQL

  - by user188693

  Don't know if this is possible, but I'd like to select records based on the field value of recur_type, where the 'm' is the day of the week. If it's a weekly recurring event, I need to make sure this is a day it recurs on, otherwise, I want to return all days. however, I'm getting an empty result set: SELECT * FROM wp_fun_bec_events WHERE start_date <= '2009-10-12' AND ( end_date >= '2009-10-12' OR (recur_end > '0' AND recur_end >= '2009-10-12' ) ) AND ('m' IN ( CASE WHEN 'recur_type' = 'weekly' THEN recur_days ELSE 's/m/t/w/r/f/a' END ) ) ORDER BY start_date, start_time Any ideas??

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• Why is comparing against "end()" iterator legal?

  - by sharptooth

  According to C++ standard (3.7.3.2/4) using (not only dereferencing, but also copying, casting, whatever else) an invalid pointer is undefined behavior (in case of doubt also see this question). Now the typical code to traverse an STL containter looks like this: std::vector<int> toTraverse; //populate the vector for( std::vector<int>::iterator it = toTraverse.begin(); it != toTraverse.end(); ++it ) { //process( *it ); } std::vector::end() is an iterator onto the hypothetic element beyond the last element of the containter. There's no element there, therefore using a pointer through that iterator is undefined behavior. Now how does the != end() work then? I mean in order to do the comparison an iterator needs to be constructed wrapping an invalid address and then that invalid address will have to be used in a comparison which again is undefined behavior. Is such comparison legal and why?

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• How do I view Visual Studio BuildLog.htm files without cutting and pasting into an external browser

  - by bgoodr

  This may or may not be specific to VS2005 (as that is the version I'm referring to for this question). I find often the case is that I see this in the Output panel inside Visual Studio 2>Build log was saved at "file://c:\\vsdll_example\MyExecRefsDll\Debug\BuildLog.htm" Now, since that looks and smells like a URL, I would have thought that I could simply left mouse click on it, or left mouse double-click on it, and a browser window of some sort would be displayed. No, that doesn't work. So, to view it, I have to cut and paste the "file://bla/bla/bla" part into an external window. Is there a way to set up Visual Studio to allow me to browse to that file directly, or view it inside Visual Studio IDE, or something to that effect, without the extra fiddling with cutting and pasting? Or is there some type of keybinding I'm not aware of? Thanks, bg

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• android: ListView.setAdapter() is causing IllegalStateException. Not sure how to fix it.

  - by Stev0

  I'm trying to populate a listview with the contents of various ListAdapters based upon the results of a switch statement nested in an OnItemClickListener. When clicking the item, the application was force closing, so I ran it through the dev tools and android debugger. Eclipse is showing me the in the main thread that the application has suspended due an IllegalStateException. I have a marginal understanding of what the particular exception indicates, but not sure how to fix it, or what in my code is causing it to be thrown. Code as follows: final ListView lv = (ListView) findViewById(R.id.main_list); final String[] autos = getResources().getStringArray(R.array.auto_array); final ListAdapter la_auto = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_2, autos); And then further down in the portion dealing with the onclicklistener gallery.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView parent, View v, int position, long id) { switch(gallery.getSelectedItemPosition()) { case 0: lv.setAdapter(la_auto); break;

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• WithEvents LinkedList is it Impossible?

  - by serhio

  What is the optimal approach to a WithEvents Collection - VB.NET? Have you any remarks on the code bellow (skipping the Nothing verifications)? The problem is when I obtain the LinkedListNode(Of Foo) in a For Each block I can set myNode.Value = something, and here is a handlers leak... -Could I override the FooCollection's GetEnumerator in this case? -No. :( cause NotInheritable Class LinkedListNode(Of T) Class Foo Public Event SelectedChanged As EventHandler End Class Class FooCollection Inherits LinkedList(Of Foo) Public Event SelectedChanged As EventHandler Protected Overloads Sub AddFirst(ByVal item As Foo) AddHandler item.SelectedChanged, AddressOf OnSelectedChanged MyBase.AddFirst(item) End Sub Protected Overloads Sub AddLast(ByVal item As Foo) AddHandler item.SelectedChanged, AddressOf OnSelectedChanged MyBase.AddLast(item) End Sub ' ------------------- ' Protected Overloads Sub RemoveFirst() RemoveHandler MyBase.First.Value.SelectedChanged, _ AddressOf OnSelectedChanged MyBase.RemoveFirst() End Sub Protected Overloads Sub RemoveLast(ByVal item As Foo) RemoveHandler MyBase.Last.Value.SelectedChanged, _ AddressOf OnSelectedChanged MyBase.RemoveLast() End Sub ' ------------------- ' Protected Sub OnSelectedChanged(ByVal sender As Object, ByVal e As EventArgs) RaiseEvent SelectedChanged(sender, e) End Sub End Class

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• How to add a suffix at the end of a string in PHP

  - by Golem

  I am trying to add a .html suffix at the end of all strings supplied by the user before it is entered into the database. Here's my code so far: strtolower(str_replace(" ", "_", $postTitle)); The above takes the title of the post the user it trying to make, turns it to lower case, replaces all white spaces with underscores and makes it ready to be entered into a database column called post_url. I just need it to do one more thing and that's to add a .html at the end of each post url. What is the function to do this?

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• Linq to NHibernate - How to return a parent object with only certain child objects included

  - by vakman

  Given a simplified model like the following: public class Enquiry { public virtual DateTime Created { get; set; } public virtual Sender Sender { get; set; } } public class Sender { public virtual IList<Enquiry> Enquiries { get; set; } } How can you construct a Linq to Nhibernate query such that it gives you back a list of senders and their enquiries where the enquiries meet some criteria. I have tried something like this: return session.Linq<Enquiry>() .Where(enquiry => enquiry.Created < DateTime.Now) .Select(enquiry => enquiry.Sender) In this case I get an InvalidCastException saying you can't cast type Sender to type Enquiry. Any pointers on how I can do this without using HQL?

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• Model of hql query firing at back end by hql engine?

  - by Maddy.Shik

  I want to understand how hibernate execute hql query internally or in other models how hql query engine works. Please suggest some good links for same? One of reason for reading is following problem. Class Branch { //lazy loaded @joincolumn(name="company_id") Company company; } Since company is heavy object so it is lazy loaded. now i have hql query "from Branch as branch where branch.Company.id=:companyId" my concern is that if for firing above query, hql engine has to retrieve company object then its a performance hit and i would prefer to add one more property in Branch class i.e. companyId. So in this case hql query would be "from Branch as branch where branch.companyId=:companyId" If hql engine first generate sql from hql followed by firing of sql query itself, then there should be no performance issue. Please let me know if problem is not understandable.

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• What are the Pros and Cons of Cascading delete and updates?

  - by Misnomer

  Hi, Maybe this is sort of a naive question...but I think that we should always have cascading deletes and updates. But I wanted to know are there problems with it and when should we should not do it? I really can't think of a case right now where you would not want to do an cascade delete but I am sure there is one...but what about updates should they be done always? So can anyone please list out the pros and cons of cascading deletes and updates ? Thanks.

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• FlexBuilder 3 Linked folders not picking up as files.

  - by Jafin

  I am using Flex Builder 3 to write a flex component. I have created a real folder path \common. Under common I create a Linked Folder to Session. Session points to a shared source folder with a item with a namespace of common\Session\ClassName. When I go to compile the project FlexBuilder warns that it was unable to find the type. if I stop using Linked folders and create a physical \common\Session\ in my project and place SessionInfo.as in the folder then it works. just in case my textual explanation is a bit obscure here is the layout. \src\common\Session\SessionInfo.as namespace of SessionInfo is common.Session. If you need any further info just let me know.

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• Trimming a vector of strings

  - by dreamlax

  I have an std::vector of std::strings containing data similar to this: [0] = "" [1] = "Abc" [2] = "Def" [3] = "" [4] = "Ghi" [5] = "" [6] = "" How can I get a vector containing the 4 strings from 1 to 4? (i.e. I want to trim all blank strings from the start and end of the vector): [0] = "Abc" [1] = "Def" [2] = "" [3] = "Ghi" Currently, I am using a forward iterator to make my way up to "Abc" and a reverse iterator to make my way back to "Ghi", and then constructing a new vector using those iterators. This method works, but I want to know if there is an easier way to trim these elements. P.S. I'm a C++ noob. Edit Also, I should mention that the vector may be composed entirely of blank strings, in which case a 0-sized vector would be the desired result.

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• Paging in SQL Server problems

  - by Manh Trinh

  I have searched for paging in SQL Server. I found most of the solution look like that What is the best way to paginate results in SQL Server But it don't meet my expectation. Here is my situation: I work on JasperReport, for that: to export the report I just need pass the any Select query into the template, it will auto generated out the report EX : I have a select query like this: Select * from table A I don't know any column names in table A. So I can't use Select ROW_NUMBER() Over (Order By columsName) And I also don't want it order by any columns. Anyone can help me do it? PS: In Oracle , it have rownum very helpful in this case. Select * from tableA where rownum > 100 and rownum <200 Paging with Oracle

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• Incremental build with continuous integration server

  - by altern

  Does any of the continuous integration servers support incremental builds or filtering mechanism? For example, I want to configure some kind of filtering (as I call it) so that committing file to the specific folder will not cause full (clean) build triggering, but will cause only incremental build. By 'incremental build' I mean process that will put only committed files to the required place and all application would not need to be rebuilt from scratch. Working with images is good example of the case when we need such filtering and thus incremental builds: why do we need to rebuild whole application if only images have been changed? What we need to do is just place images to the dedicated place on server.

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