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  • Running for loop depending on size of string vector

    - by xbonez
    I have made a string vector vector actor_; and then added elements in it using push_back. I now want to display all of them, for which I need to run a loop according to the number of elements in the vector. For that, I need to run the following loop: for (int i = 0; i < (int)actor_.size; i++) { } but this returns the following error: error C2440: 'type cast' : cannot convert from 'unsigned int (__thiscall std::vector<_Ty::* )(void) const' to 'int' 1 with 1 [ 1 _Ty=std::string 1 ] 1 There is no context in which this conversion is possible

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  • c# short if statement not working with int? (int=null)

    - by kobe
    I am trying to shorten my code by using short-if: int? myInt=myTextBox.Text == "" ? null : Convert.ToInt32(myTextBox.Text); But I'm getting the following error: Type of conditional expression cannot be determined because there is no implicit conversion between '' and 'int' The following works: int? myInt; if (myTextBox.Text == "") //if no text in the box myInt=null; else myInt=Convert.ToInt32(myTextBox.Text); And if I replace the 'null' in integer (say '4') it also works: int? myInt=myTextBox.Text == "" ? 4: Convert.ToInt32(myTextBox.Text);

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  • Efficient way to access a mapping of identifiers in Python

    - by sixbelo
    I am writing an app to do a file conversion and part of that is replacing old account numbers with a new account numbers. Right now I have a CSV file mapping the old and new account numbers with around 30K records. I read this in and store it as dict and when writing the new file grab the new account from the dict by key. My question is what is the best way to do this if the CSV file increases to 100K+ records? Would it be more efficient to convert the account mappings from a CSV to a sqlite database rather than storing them as a dict in memory?

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  • Would like some modelling tips for dependent values

    - by orjan
    I'm working on a model for a simple fishing competition and I have some issues with my design. The main class for the fishing game is Capture and it looks like this: public class Capture : Entity { public virtual int Weight { get; set; } public virtual int Length { get; set; } public virtual DateTime DateForCapture { get; set; } public virtual User CapturedBy { get; set; } public virtual Species Species { get; set; } } So far there´s no problem but I'm not really sure how to model the game. Every Species is connected to a reference weight that changes from year to year The number of point for a capture is its Weight divided by the current reference weight for the species. One way to solve the problem is to connect a capture to SpeciesReferenceWeight instead of Species public class SpeciesReferenceWeight : Entity { public virtual Species Species { get; set; } public virtual int ReferenceWeight { get; set; } public virtual int Year { get; set; } } But in that way that Capture is connected to the implementation details of the game and from my point of view a capture is still a capture even if it's not included in a game. The result I'm aiming for is like: http://hornalen.net/fishbonkern/2007/ that I wrote a couple of years ago with brute force sql and no domain model. I would be very happy for all kinds of feeback on this issue.

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  • Python, web log data mining for frequent patterns

    - by descent
    Hello! I need to develop a tool for web log data mining. Having many sequences of urls, requested in a particular user session (retrieved from web-application logs), I need to figure out the patterns of usage and groups (clusters) of users of the website. I am new to Data Mining, and now examining Google a lot. Found some useful info, i.e. querying Frequent Pattern Mining in Web Log Data seems to point to almost exactly similar studies. So my questions are: Are there any python-based tools that do what I need or at least smth similar? Can Orange toolkit be of any help? Can reading the book Programming Collective Intelligence be of any help? What to Google for, what to read, which relatively simple algorithms to use best? I am very limited in time (to around a week), so any help would be extremely precious. What I need is to point me into the right direction and the advice of how to accomplish the task in the shortest time. Thanks in advance!

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  • Why SQL functions are faster than UDF

    - by Zerotoinfinite
    Though it's a quite subjective question but I feel it necessary to share on this forum. I have personally experienced that when I create a UDF (even if that is not complex) and use it into my SQL it drastically decrease the performance. But when I use SQL inbuild function they happen to work pretty faster. Conversion , logical & string functions are clear example of that. So, my question is "Why SQL in build functions are faster than UDF"? and it would be an advantage if someone can guide me how can I judge/manipulate function cost either mathematically or logically.

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  • Should I use ObservableCollections in my Model in M-V-VM

    - by Bill Jeeves
    I'm completely new to M-V-VM and very new to Silverlight, just reading about it for the first time today. As a sample, I am creating a model containing a list of items. My (Silverlight 4) View contains a listbox and my ViewModel will look to the model to retrieve the collection that the listbox will bind to. My question is this. I think it would be good to use an ObservableCollection to hold the items that the listbox binds to. This would be an ObseravleCollection in the ViewModel. Should I also use this type of collection in the model, or should I use another collection type and do smoe conversion between model and viewmodel?

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  • How can I synchronize one set of data with another?

    - by RenderIn
    I have an old database and a new database. The old records were converted to the new database recently. All our old applications continue to point to the old database, but the new applications point to the new database. Currently the old database is the only one being updated, so throughout the day the new database becomes out of sync. It is acceptable for the new database to be out of sync for a day, so until all our applications are pointed to the new database I just need to write a nightly cron job that will bring it up to date. I do not want to purge the new database and run the complete conversion script each night, as that would reduce uptime and would create a mess in our auditing of that table. I'm thinking about selecting all the data from the old database, converting it to the new database structure in memory, and then checking for the existence of each record before inserting it in the new database. After that's done, I'd select everything from the new database and check if it exists in the old one, and if not delete it. Is this the simplest way to do this?

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  • Heap Algorithmic Issue

    - by OberynMarDELL
    I am having this algorithmic problem that I want to discuss about. Its not about find a solution but about optimization in terms of runtime. So here it is: Suppose we have a race court of Length L and a total of N cars that participate on the race. The race rules are simple. Once a car overtakes an other car the second car is eliminated from the race. The race ends when no more overtakes are possible to happen. The tricky part is that the k'th car has a starting point x[k] and a velocity v[k]. The points are given in an ascending order, but the velocities may differ. What I've done so far: Given that a car can get overtaken only by its previous, I calculated the time that it takes for each car to reach its next one t = (x[i] - x[i+1])/(v[i] - v[i+1]) and I insert these times onto a min heap in O(n log n). So in theory I have to pop the first element in O(logn), find its previous, pop it as well , update its time and insert it in the heap once more, much like a priority queue. My main problem is how I can access specific points of a heap in O(log n) or faster in order to keep the complexity in O(n log n) levels. This program should be written on Haskell so I would like to keep things simple as far as possible EDIT: I Forgot to write the actual point of the race. The goal is to find the order in which cars exit the game

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  • How to speed up saving a UIImagePickerController image from the camera to the filesystem via UIImagePNGRepresentation()?

    - by kazuhito0000
    I'm making an applications that let users take a photo and show them both in thumbnail and photo viewer. I have NSManagedObject class called photo and photo has a method that takes UIImage and converts it to PNG using UIImagePNGRepresentation() and saves it to filesystem. After this operation, resize the image to thumbnail size and save it. The problem here is UIImagePNGRepresentation() and conversion of image size seems to be really slow and I don't know if this is a right way to do it. Tell me if anyone know the best way to accomplish what I want to do. Thank you in advance.

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  • problem with sql statement using vb.net

    - by newBie
    hi i got some problem i got this 3 line statement: Dim infoID As Integer = objCommand1.ExecuteScalar() Dim strSQL2 As String = "insert into feedBackHotel (infoID, feedBackView) values(" + infoID + ",'" + FeedBack + "')" Dim objCommand2 As New SqlCommand(strSQL2, conn) objCommand2.ExecuteNonQuery() the problem here is..the strSQL2 can capture the infoID from previous statement, but it didnt insert into the database. it will pop out this error "Conversion from string "insert into feedBackHotel (infoI" to type 'Double' is not valid." in both table related, use same data type (int) but for the feedBackHotel's infoID i allow it to be null..bcoz if i make it not null, it will show another error.. im using vb.net ..can anyone help?

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  • Designing for varying mobile device resolutions, i.e. iPhone 4 & iPhone 3G

    - by Josh
    As the design community moves to design applications & interfaces for mobile devices, a new problem has arisen: Varying Screen DPI's. Here's the situation: Touch: * iPhone 3G/S ~ 160 dpi * iPhone 4 ~ 300 dpi * iPad ~ 126 dpi * Android device @ 480p ~ 200 dpi Point / click: * Laptop @ 720p ~ 96 dpi * Desktop @ 720p ~ 72 dpi There is certainly a clear distinction between desktop and mobile so having two separate front-ends to the same app is logical, especially when considering one is "touch"-based and the other is "point/click"-based. The challenge lies in designing static graphical elements that will scale between, say, 160 dpi and 300+ dpi, and get consistent and clean design across zoom levels. Any thoughts on how to approach this? Here are some scenarios, but each has drawbacks as well: * Design a single set of assets (high resolution), then adjust zoom levels based on detected resolution / device o Drawbacks: Performance caused by code layering, varying device support of Zoom * Develop & optimize multiple variations of image and CSS assets, then hide / show each based on device o Drawbacks: Extra work in design & QA. Anyone have thoughts or experience on how to deal with this? We should certainly be looking at methods that use / support HTML5 and CSS3.

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  • style ul with width to accommodate items

    - by Tallmaris
    Sorry I could not find a similar answer on SO. I have the following markup (generated by jquery ui autocomplete but this is not the issue here) <ul style="z-index: 1; display: block; border: thin solid red; width: 200px;"> <li> <a> <div style="font-size: 0.85em;"> <span style="float: right; padding-left: 10px; color: gray;"> United Kingdom </span> <span style="">text text text text text</span> </div> </a> </li> </ul> As you can see in this fiddle: http://jsfiddle.net/fVr8P/2/ the text wraps because the width is limited and the country span is "floating". What I would like would be for the width to enlarge to accommodate the full length, but if I put width: auto; it will expand to 100%. Background The ul is of course coming from jquery ui autocomplete. I am styling the results a bit using the autocomplete.html extension. Problem is that everything is working ok in firefox an chrome because the autocomplete is set to the correct width on creation. in IE this does not happen (width is too small) so the text wraps. I am hping to come to a simple css only solution, without fiddling around in jQuery.

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  • C++: use array of strings wrapped in namespace?

    - by John D.
    I got the following code, wishing to wrap a group of strings nicely in a namespace: namespace msgs { const int arr_sz = 3; const char *msg[arr_sz] = {"blank", "blank", "blank" }; msg[0] = "Welcome, lets start by getting a little info from you!\n"; msg[1] = "Alright, bla bla bla.."; msg[2] = "etc."; } The code inside works nicely inside a function, but I don't know how to return an array from it. The namespace idea LOOKS fine, but it returns on the last three lines: error: expected constructor, destructor, or type conversion before ‘=’ token Why can't I define the array inside a namespace, do I need to do something first? It's nice because I can call it like printf(msgs::msg[1]) etc. I want to do this I just can't wrap my head around what's wrong :(

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  • How to center string output using printf() and variable width? [java]

    - by Khan
    I'm creating an output in Java using printf() to create table headers. One of the columns needs variable width. Basically it should look like this: //two coords Trial Column Heading 1 (20,30)(30,20) //three coords Trial Column Heading 1 (20,40)(50,10)(90,30) I tried to use: int spacing = numCoords * 7; //size of column printf("Trial %*^s", column, "Column Heading"); But I keep getting output errors when I try to use * or ^ in the conversion statement. Does anyone have any idea what the correct formatting string should be?

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  • What is the most efficient way to handle points / small vectors in JavaScript?

    - by Chris
    Currently I'm creating an web based (= JavaScript) application thata is using a lot of "points" (= small, fixed size vectors). There are basically two obvious ways of representing them: var pointA = [ xValue, yValue ]; and var pointB = { x: xValue, y: yValue }; So translating my point a bit would look like: var pointAtrans = [ pointA[0] + 3, pointA[1] + 4 ]; var pointBtrans = { x: pointB.x + 3, pointB.y + 4 }; Both are easy to handle from a programmer point of view (the object variant is a bit more readable, especially as I'm mostly dealing with 2D data, seldom with 3D and hardly with 4D - but never more. It'll allways fit into x,y,z and w) But my question is now: What is the most efficient way from the language perspective - theoretically and in real implementations? What are the memory requirements? What are the setup costs of an array vs. an object? ... My target browsers are FireFox and the Webkit based ones (Chromium, Safari), but it wouldn't hurt to have a great (= fast) experience under IE and Opera as well...

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  • memory management: am i doing something wrong here?

    - by z s
    Hi, In a very small number of cases in my iphone app, I get a crash after the for loop in the code below: ABAddressBookRef addressBookInit = ABAddressBookCreate(); CFMutableArrayRef abContacts = (CFMutableArrayRef)ABAddressBookCopyArrayOfAllPeople(addressBookInit); // get array of all contacts CFArraySortValues (abContacts, CFRangeMake(0, CFArrayGetCount(abContacts)), (CFComparatorFunction)ABPersonComparePeopleByName, (void *)ABPersonGetSortOrdering()); NSArray *copypeople = (NSArray *) abContacts; NSMutableArray *tempTheadlist = [[NSMutableArray alloc] init]; for (int i=0; i < copypeople.count; i++) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; ABRecordRef record = [copypeople objectAtIndex:i]; if (blah blah) [tempThreadList addObject: someObject]; [pool release]; } // POINT OF CRASH AFTER LOOP ENDS if (tempTheadlist.count > 0) [NSThread detachNewThreadSelector: @selector(loading_pictures:) toTarget:self withObject:tempTheadlist]; [tempTheadlist release]; [copypeople release]; CFRelease(addressBookInit); Any reason why it should crash at any point here?

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  • rails route question

    - by badnaam
    I am trying to build a search functionality which at a high level works like this. 1 - I have a Search model, controller with a search_set action and search views/partial to render the search. 2 - At the home page a serach form is loaded with an empty search object or a search object initialized with session[:search] (which contains user search preferences, zip code, proximity, sort order, per page etc). This form has a post(:put) action to search_set. 3 - When a registered user performs a set the params of the search form are collected and a search record is saved against that user. If a unregistered user performs a search then the search set action simply stores the params in the session[:search]. In either case, the search is executed with the given params and the results are displayed. At this point the url of in the location bar is something like.. http://localhost:3000/searches/search_set?stype=1 At this point if the user simply hits enter on the location bar, I get an error that says "No action responded to show" I am guessing because the URL contains search_set which uses a put method and even though I have a search_show (:get) action (which simply reruns the search in the session or saved in the database) does not get called. How can I handle this situation where I can route a user hitting enter into the location bar to a get method? If this does not explain the problem , please let me know I can share more details/code etc. Thanks!

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  • Assigning a pointer variable to a const int in C++?

    - by John
    I'm wondering if anyone can explain the following to me: If I write int i = 0; float* pf = i; I get a compile error (gcc 4.2.1): error: invalid conversion from ‘int’ to ‘float*’ Makes sense - they are obviously two completely different types. But if instead I write const int i = 0; float* pf = i; It compiles without error. Why should the 'const' make a difference on the right hand side of the assignment? Isn't part of the idea of the 'const' keyword to be able to enforce type constraints for constant values? Any explanation I have been able to come up with feels kind of bogus. And none of my explanations also explain the fact that const int i = 1; float* pf = i; fails to compile. Can anyone offer an explanation?

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  • C++ - repeatedly using istringstream

    - by Goffrey
    I have a code for reading files with float numbers on line stored like this: "3.34|2.3409|1.0001|...|1.1|". I would like to read them using istringstream, but it doesn't work as I would expect: string row; string strNum; istringstream separate; // textovy stream pro konverzi while ( getline(file,row) ) { separate.str(row); // = HERE is PROBLEM = while( getline(separate, strNum, '|') ) { // using delimiter flNum = strToFl(strNum); // my conversion insertIntoMatrix(i,j,flNum); // some function j++; } i++; } In marked point, row is copied into separate stream only first time. In next iteration it doesn't work and it does nothing. I expected it is possible to be used more times without constructing new istringstream object in every iteration.

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  • Pointers to a typed variable in C#: Interfase, Generic, object or Class? (Boxing/Unboxing)

    - by PaulG
    First of all, I apologize if this has been asked a thousand times. I read my C# book, I googled it, but I can't seem to find the answer I am looking for, or I am missing the point big time. I am very confused with the whole boxing/unboxing issue. Say I have fields of different classes, all returning typed variables (e.g. 'double') and I would like to have a variable point to any of these fields. In plain old C I would do something like: double * newVar; newVar = &oldVar; newVar = &anotherVar; ... In C#, it seems I could do an interfase, but would require that all fields be properties and named the same. Breaks apart when one of the properties doesn't have the same name or is not a property. I could also create a generic class returning double, but seems a bit absurd to create a class to represent a 'double', when a 'double' class already exists. If I am not mistaken, it doesn't even need to be generic, could be a simple class returning double. I could create an object and box the typed variable to the newly created object, but then I would have to cast every time I use it. Of course, I always have the unsafe option... but afraid of getting to unknown memory space, divide by zero and bring an end to this world. None of these seem to be the same as the old simple 'double * variable'. Am I missing something here?

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  • Can't add an object using EF and SQL Compact

    - by kamilo
    Hello, I have some very simple SQL Compact database. I would like to use Entity Framework to access the database but for some reason I can't add an object to this database using EF. Here is the code using (pos_inglotEntities posInglotCtx = new pos_inglotEntities()) { posInglotCtx.Connection.Open(); CT_POS_OITM item = new CT_POS_OITM() { ItemCode = "123", ItemName="abc"}; try { posInglotCtx.AddToCT_POS_OITM(item); posInglotCtx.SaveChanges(); } catch (Exception e) { } posInglotCtx.Connection.Close(); } After running this code my database is still empty although if I run it once again I get "duplicate values" exception. But again database is empty. I created this db using PrimeWorks conversion tool from standard sql server database. What is going on? Thanks in advance

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  • Embedded Development Board

    - by ALF3130
    I'm new to the embedded development world and am looking to get my very first board. After some research, I realize that there aren't many choices with FPUs. This is important in my project as I'm going to be doing quite a bit of floating point computations. I found the Mini2440 which seems to run on the ARM920T core. This particular unit is perfect for my needs (decent price, all the right I/O ports, and a touch screen to boot) but it seems that it doesn't have an FPU. I don't know how big of a penalty I'd be paying for FP emulation, so I'm unsure of whether to pull the trigger on this one. That said: Can someone please confirm whether this product (Mini2440) has an FPU or not? My project will do image capture and analysis. Does anyone have any experience with running things like OpenMP on such platforms? Please suggest any other similar boards in the = $200 price range that have an FPU. This world is new to me. Any other advice or things I should be aware of is much appreciated.

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  • Using an iterator without its container

    - by User1
    I am mixing some C and C++ libraries and have only a single pointer available to do some work in a callback function. All I need to do is iterate through a vector. Here's a simplified, untested example: bool call_back(void* data){ done=... if (!done) cout << *data++ << endl; return done; } Note that this function is in an extern "C" block in C++. call_back will be called until true is returned. I want it to cout the next element each time it's called. data is a pointer to something that I can pass from elsewhere in the code (an iterator in the above example, but can be anything). Something from data will likely be used to calculate done. I see two obvious options to give to data: Have data point to my vector. Have data point to an iterator of my vector. I can't use an iterator without having the .end() method available, right? I can't use a vector alone (unless maybe I start removing its data). I could make a struct with both vector and iterator, but is there a better way? What would you do?

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  • (Java) Get value of string loaded into dynamic-type object?

    - by Michael
    I'm very new to Java (~10 days), so my code is probably pretty bad, but here's what I've got: ArgsDataHolder argsData = new ArgsDataHolder(); // a class that holds two // ArrayList's where each element // representing key/value args Class thisArgClass; String thisArgString; Object thisArg; for(int i=2; i< argsString.length; i++) { thisToken = argsString[i]; thisArgClassString = getClassStringFromToken(thisToken).toLowerCase(); System.out.println("thisArgClassString: " + thisArgClassString); thisArgClass = getClassFromClassString(thisArgClassString); // find closing tag; concatenate middle Integer j = new Integer(i+1); thisArgString = getArgValue(argsString, j, "</" + thisArgClassString + ">"); thisArg = thisArgClass.newInstance(); thisArg = thisArgClass.valueOf(thisArgString); argsData.append(thisArg, thisArgClass); } The user basically has to input a set of key/value arguments into the command prompt in this format: <class>value</class>, e.g. <int>62</int>. Using this example, thisArgClass would be equal to Integer.class, thisArgString would be a string that read "62", and thisArg would be an instance of Integer that is equal to 62. I tried thisArg.valueOf(thisArgString), but I guess valueOf(<String>) is only a method of certain subclasses of Object. For whatever reason, I can't seem to be able to cast thisArg to thisArgClass (like so: thisArg = (thisArgClass)thisArgClass.newInstance();, at which point valueOf(<String>) should become accessible. There's got to be a nice, clean way of doing this, but it is beyond my abilities at this point. How can I get the value of the string loaded into a dynamically-typed object (Integer, Long, Float, Double, String, Character, Boolean, etc.)? Or am I just overthinking this, and Java will do the conversion for me? :confused:

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