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• How to delete duplicate vectors within a multidimensional vector?

  - by David

  I have a vector of vectors: vector< vector<int> > BigVec; It contains an arbitrary number of vectors, each of an arbitrary size. I want to delete not duplicate elements of each vector, but any vectors that are the exact same as another. I don't need to preserve the order of the vectors so I can sort etc.. It should be a really simple problem to solve but I'm new to this, my (not-working) best effort: for (int i = 0; i < BigVec.size(); i++) { for (int j = 1; j < BigVec.size() ; j++ ) { if (BigVec[i][0] == BigVec [j][i]); { BigVec.erase(BigVec.begin() + j); i = 0; // because i get the impression deleting a j = 1; // vector messes up a simple iteration through } } } I think there might be a solution using Unique(), but I can't get that to work either.

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• Why would bitmap outperform vector, as3?

  - by VideoDnd

  Why would bitmap outperform vector? My Flash is for a large Kiosk, with rich media requirements and must function accurately as a counter. I want to keep everything vector for scalability. When I did a simple FPS test, I noticed my Bitmap version performed perfectly, and the all vector file was noticeably slower. PLEASE EXPLAIN • vector performance• what graphic standards I can apply• solutions for using vector KIOSK TEST ANIMATION RESULTS • only text and bitmap perform well, not vector • background and clouds OK, but more layers slow it down

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• Ray Generation Inconsistency

  - by Myx

  I have written code that generates a ray from the "eye" of the camera to the viewing plane some distance away from the camera's eye: R3Ray ConstructRayThroughPixel(...) { R3Point p; double increments_x = (lr.X() - ul.X())/(double)width; double increments_y = (ul.Y() - lr.Y())/(double)height; p.SetX( ul.X() + ((double)i_pos+0.5)*increments_x ); p.SetY( lr.Y() + ((double)j_pos+0.5)*increments_y ); p.SetZ( lr.Z() ); R3Vector v = p-camera_pos; R3Ray new_ray(camera_pos,v); return new_ray; } ul is the upper left corner of the viewing plane and lr is the lower left corner of the viewing plane. They are defined as follows: R3Point org = scene->camera.eye + scene->camera.towards * radius; R3Vector dx = scene->camera.right * radius * tan(scene->camera.xfov); R3Vector dy = scene->camera.up * radius * tan(scene->camera.yfov); R3Point lr = org + dx - dy; R3Point ul = org - dx + dy; Here, org is the center of the viewing plane with radius being the distance between the viewing plane and the camera eye, dx and dy are the displacements in the x and y directions from the center of the viewing plane. The ConstructRayThroughPixel(...) function works perfectly for a camera whose eye is at (0,0,0). However, when the camera is at some different position, not all needed rays are produced for the image. Any suggestions what could be going wrong? Maybe something wrong with my equations? Thanks for the help.

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• How to shrink-to-fit an std::vector in a memory-efficient way?

  - by dehmann

  I would like to 'shrink-to-fit' an std::vector, to reduce its capacity to its exact size, so that additional memory is freed. The standard trick seems to be the one described here: template< typename T, class Allocator > void shrink_capacity(std::vector<T,Allocator>& v) { std::vector<T,Allocator>(v.begin(),v.end()).swap(v); } The whole point of shrink-to-fit is to save memory, but doesn't this method first create a deep copy and then swaps the instances? So at some point -- when the copy is constructed -- the memory usage is doubled? If that is the case, is there a more memory-friendly method of shrink-to-fit? (In my case the vector is really big and I cannot afford to have both the original plus a copy of it in memory at any time.)

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• Is there a version of the removeElement function in Go for the vector package like Java has in its V

  - by Brian T Hannan

  I am porting over some Java code into Google's Go language and I converting all code except I am stuck on just one part after an amazingly smooth port. My Go code looks like this and the section I am talking about is commented out: func main() { var puzzleHistory * vector.Vector; puzzleHistory = vector.New(0); var puzzle PegPuzzle; puzzle.InitPegPuzzle(3,2); puzzleHistory.Push(puzzle); var copyPuzzle PegPuzzle; var currentPuzzle PegPuzzle; currentPuzzle = puzzleHistory.At(0).(PegPuzzle); isDone := false; for !isDone { currentPuzzle = puzzleHistory.At(0).(PegPuzzle); currentPuzzle.findAllValidMoves(); for i := 0; i < currentPuzzle.validMoves.Len(); i++ { copyPuzzle.NewPegPuzzle(currentPuzzle.holes, currentPuzzle.movesAlreadyDone); copyPuzzle.doMove(currentPuzzle.validMoves.At(i).(Move)); // There is no function in Go's Vector that will remove an element like Java's Vector //puzzleHistory.removeElement(currentPuzzle); copyPuzzle.findAllValidMoves(); if copyPuzzle.validMoves.Len() != 0 { puzzleHistory.Push(copyPuzzle); } if copyPuzzle.isSolutionPuzzle() { fmt.Printf("Puzzle Solved"); copyPuzzle.show(); isDone = true; } } } } If there is no version available, which I believe there isn't ... does anyone know how I would go about implementing such a thing on my own?

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• Array Concatenation in C#

  - by Betamoo

  1- How to smartly initialize an Array with 2 (or more) other arrays in C#? double[] d1=new double[5]; double[] d2=new double[3]; double[] dTotal=new double[8];// I need this to be {d1 then d2} 2- Another question: How to concatenate C# arrays efficiently? Thanks

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• Finding the centroid of a polygon?

  - by user146780

  I have tried: for each vertex, add to total, divide by number of verities to get center. I'v also tried: Find the topmost, bottommost - get midpoint... find leftmost, rightmost, find midpoint. Both of these did not return the perfect center because I'm relying on the center to scale a polygon. I want to scale my polygons so I may put a border around them. What is the best way to find the centroid of a polygon given that the polygon may be concave, convex and have many many sides of various lengths. Thanks

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• Is the old vector get cleared? If yes, how and when?

  - by user180866

  I have the following code: void foo() { vector<double> v(100,1); // line 1 // some code v = vector<double>(200,2); // line 2 // some code } what happened to the vector of size 100 after the second line? Is it gets cleared by itself? If the answer is yes, how and when it is cleared? By the way, is there any other "easy and clean" ways to change the vector as in line 2? I don't want things like v.resize(200); for (int i=0; i<200; i++) v[i] = 2;

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• C++ vector<T>::iterator operator +

  - by Tom

  Hi, Im holding an iterator that points to an element of a vector, and I would like to compare it to the next element of the vector. Here is what I have Class Point{ public: float x,y; } //Somewhere in my code I do this vector<Point> points = line.getPoints(); foo (points.begin(),points.end()); where foo is: void foo (Vector<Point>::iterator begin,Vector<Point>::iterator end) { std::Vector<Point>::iterator current = begin; for(;current!=end-1;++current) { std::Vector<Point>::iterator next = current + 1; //Compare between current and next. } } I thought that this would work, but current + 1 is not giving me the next element of the vector. I though operator+ was the way to go, but doesnt seem so. Is there a workaround on this? THanks

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• fastest engine to convert PDF into PNG

  - by skyde

  I would like to know which of the opensource PDF engine can convert a pdf into a image the fastest. I don't care about the quality of the result (antialiasing ...) For my project it need to be very very fast. I would probably need to build my own but i dont wan't to start from scratch.

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• How to restrict the range of elements of C++ STL vector?

  - by cambr

  vector<int> l; for(int i=0;i<10;i++){ l.push_back(i); } I want the vector to only be able to store numbers from a specified range (or set). How can that be done, in general? In particular, I want to restrict the vector to beonly be able to store single digits. So, if I do a l[9]++, it should give me an error or warn me. (because 10 is not a single digit number). Similarly, l[0]-- should warn me. Is there a way to do this using C++ STL vector?

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• Attribute vector emptying itself

  - by ravloony

  Hello, I have two classes, derived from a common class. The common class has a pure virtual function called execute(), which is implemented in both derived classes. In the inherited class I have an attribute which is a vector. In both execute() methods I overwrite this vector with a result. I access both classes from a vector of pointers to their objects. The problem is when I try to access the result vector form outside the objects. In one case I can get the elements (which are simply pointers), in the other I cannot, the vector is empty. Code: class E; class A{ protected: vector<E*> _result; public: virtual void execute()=0; vector<E*> get_result(); }; vector<E*> A::get_result() { return _result; } class B : public A { public: virtual void execute(); }; B::execute() { //... _result = tempVec; return; } class C : public A { public: virtual void execute(); }; C::execute() { //different stuff to B _result = tempvec; return; } main() { B* b = new B(); C* c = new C(); b->execute(); c->execute(); b->get_result();//returns full vector c->get_result(); //returns empty vector!! } I have no idea what is going on here... I have tried filling _result by hand from a temp vector in the offending class, doing the same with vector::assign(), nothing works. And the other object works perfectly. I must be missing something.... Any help would be greatly appreciated.

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• which is better in general, map or vector in c++?

  - by tsubasa

  As I know that accessing an element in vector takes constant time while in map takes logarithmic time. However, storing a map takes less memory than storing a vector. Therefore, I want to ask which one is better in general? I'm considering using one of those two in my program, which has about 1000 elements. I plan to use 3 dimensional vector, which would take 1000x1000x1000 elements.

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• Does std::vector change its address? How to avoid

  - by kunigami

  Since vector elements are stored contiguously, I guess it may not have the same address after some push_back's , because the initial allocated space could not suffice. I'm working on a code where I need a reference to an element in a vector, like: int main(){ vector<int> v; v.push_back(1); int *ptr = &v[0]; for(int i=2; i<100; i++) v.push_back(i); cout << *ptr << endl; //? return 0; } But it's not necessarily true that ptr contains a reference to v[0], right? How would be a good way to guarantee it? My first idea would be to use a vector of pointers and dynamic allocation. I'm wondering if there's an easier way to do that? PS.: Actually I'm using a vector of a class instead of int, but I think the issues are the same.

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• How to initialize std::vector from C-style array?

  - by dehmann

  What is the cheapest way to initialize a std::vector from a C-style array? Example: In the following class, I have a vector, but due to outside restrictions, the data will be passed in as C-style array: class Foo { std::vector<double> w_; public: void set_data(double* w, int len){ // how to cheaply initialize the std::vector? } Obviously, I can call w_.resize() and then loop over the elements, or call std::copy(). Are there any better methods?

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• Use IIS Application Initialization for keeping ASP.NET Apps alive

  - by Rick Strahl

  Ever want to run a service-like, always-on application inside of ASP.NET instead of creating a Windows Service or running a Console application? Need to make sure that your ASP.NET application is always running and comes up immediately after an Application Pool restart even if nobody hits your site? The IIS Application Initialization Module provides this functionality in IIS 7 and later, making it much easier to create always-on ASP.NET applications that can act like a service.

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• Reduce Repetitive Initialization Code in C++ Applications by Using Delegating Constructors

  You're often required to repeat identical pieces of initialization code in every constructor of a class that declares multiple constructors. That's because unlike a few other programming languages, The C++ programming language doesn't allow a constructor to call another constructor of the same class. Luckily, this problem is about to disappear with the recent approval of a new C++0x feature called delegating constructors which are explained in this C++ tutorial.

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• Resultant Vector Algorithm for 2D Collisions

  - by John

  I am making a Pong based game where a puck hits a paddle and bounces off. Both the puck and the paddles are Circles. I came up with an algorithm to calculate the resultant vector of the puck once it meets a paddle. The game seems to function correctly but I'm not entirely sure my algorithm is correct. Here are my variables for the algorithm: Given: velocity = the magnitude of the initial velocity of the puck before the collision x = the x coordinate of the puck y = the y coordinate of the puck moveX = the horizontal speed of the puck moveY = the vertical speed of the puck otherX = the x coordinate of the paddle otherY = the y coordinate of the paddle piece.horizontalMomentum = the horizontal speed of the paddle before it hits the puck piece.verticalMomentum = the vertical speed of the paddle before it hits the puck slope = the direction, in radians, of the puck's velocity distX = the horizontal distance between the center of the puck and the center of the paddle distY = the vertical distance between the center of the puck and the center of the paddle Algorithm solves for: impactAngle = the angle, in radians, of the angle of impact. newSpeedX = the speed of the resultant vector in the X direction newSpeedY = the speed of the resultant vector in the Y direction Here is the code for my algorithm: int otherX = piece.x; int otherY = piece.y; double velocity = Math.sqrt((moveX * moveX) + (moveY * moveY)); double slope = Math.atan(moveX / moveY); int distX = x - otherX; int distY = y - otherY; double impactAngle = Math.atan(distX / distY); double newAngle = impactAngle + slope; int newSpeedX = (int)(velocity * Math.sin(newAngle)) + piece.horizontalMomentum; int newSpeedY = (int)(velocity * Math.cos(newAngle)) + piece.verticalMomentum; for those who are not program savvy here is it simplified: velocity = v(moveX² + moveY²) slope = arctan(moveX / moveY) distX = x - otherX distY = y - otherY impactAngle = arctan(distX / distY) newAngle = impactAngle + slope newSpeedX = velocity * sin(newAngle) + piece.horizontalMomentum newSpeedY = velocity * cos(newAngle) + piece.verticalMomentum My Question: Is this algorithm correct? Is there an easier/simpler way to do what I'm trying to do?

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• How to print a rendered website to pdf or vector graphics?

  - by Lo Sauer

  This is a crucial question to many: Searching the web, I have found several command line tools that allow you to convert a HTML-document to a PDF-document, however they all seem to use their own, and rather incomplete rendering engine, resulting in poor quality How can you print the rendered output of a modern web-browser to pdf, (and/or svg) whilst retaining as much vector graphics as possible? There is a solution called: webkit-pdf (which renders everything to bitmap graphics) I am looking for options, alternatives, suggestions perhaps even a printer-driver or webservices? Thanks

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• "initialization error: class file has wrong version" message in JDeveloper 10.1.2.x

  - by [email protected]

  The "initialization error: class file has wrong version" has become a somewhat recurrent error message thrown by JDeveloper 10.1.2.x as newer JDKs have been released in the last years. Note that JDeveloper 10.1.2 was developed to run with JDK 1.4.2. The reasons for this error message to be thrown include: A JDK version higher than 1.4.2 is being used and some unexpected incompatibility conflicts can occur because of that Some of the libraries used on the workspace and/or project were compiled with newer JDK version So, it is strongly recommended to use newer JDeveloper versions (10.1.3 - 11g) for newer JDKs. JDeveloper 10.1.2 will be desupported in December 2010 (or later depending on the support contract). Further information about this can be seen at http://www.oracle.com/support/library/brochure/lifetime-support-middleware.pdf

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• SOA Suite 11g: Unable to start domain (Error occurred during initialization of VM)

  - by Chris Tomkins

  If you have recently installed SOA Suite, created a domain and then tried to start it only to find it fails with the error: Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine. the solution is to edit the file <domain home>\bin\setSOADomainEnv.cmd/sh (depending on your platform) and modify the line: set DEFAULT_MEM_ARGS=-Xms512m -Xmx1024m to something like: set DEFAULT_MEM_ARGS=-Xms512m -Xmx768m Save the file and then try to start your domain again. Everything should now work at least it does on the Dell Latitude 630 laptop with 4Gb RAM that I have. Technorati Tags: soa suite,11g,java,troubleshooting,problems,domain

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• Check for Instant File Initialization

  - by TiborKaraszi

  Instant File initialization, IFI, is generally a good thing to have. Check out this earlier blog post of mine f you don't know what IFI is and why it is a good thing: blog . The purpose of this blog post is to provide a simple script you can use to check if you have IFI turned on. Note that the script below uses undocumented commands, and might take a while if you have a large errorlog file... USE MASTER ; SET NOCOUNT ON -- *** WARNING: Undocumented commands used in this script !!! *** -- --Exit...(read more)

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• C++ STL: How to iterate vector while requiring access to element and its index?

  - by Ashwin

  I frequently find myself requiring to iterate over STL vectors. While I am doing this I require access to both the vector element and its index. I used to do this as: typedef std::vector<Foo> FooVec; typedef FooVec::iterator FooVecIter; FooVec fooVec; int index = 0; for (FooVecIter i = fooVec.begin(); i != fooVec.end(); ++i, ++index) { Foo& foo = *i; if (foo.somethingIsTrue()) // True for most elements std::cout << index << ": " << foo << std::endl; } After discovering BOOST_FOREACH, I shortened this to: typedef std::vector<Foo> FooVec; FooVec fooVec; int index = -1; BOOST_FOREACH( Foo& foo, fooVec ) { ++index; if (foo.somethingIsTrue()) // True for most elements std::cout << index << ": " << foo << std::endl; } Is there a better or more elegant way to iterate over STL vectors when both reference to the vector element and its index is required? I am aware of the alternative: for (int i = 0; i < fooVec.size(); ++i) But I keep reading about how it is not a good practice to iterate over STL containers like this.

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• What is a truly empty std::vector in C++?

  - by RyanG

  I've got a two vectors in class A that contain other class objects B and C. I know exactly how many elements these vectors are supposed to hold at maximum. In the initializer list of class A's constructor, I initialize these vectors to their max sizes (constants). If I understand this correctly, I now have a vector of objects of class B that have been initialized using their default constructor. Right? When I wrote this code, I thought this was the only way to deal with things. However, I've since learned about std::vector.reserve() and I'd like to achieve something different. I'd like to allocate memory for these vectors to grow as large as possible because adding to them is controlled by user-input, so I don't want frequent resizings. However, I iterate through this vector many, many times per second and I only currently work on objects I've flagged as "active". To have to check a boolean member of class B/C on ever iteration is silly. I don't want these objects to even BE there for my iterators to see when I run through this list. Is reserving the max space ahead of time and using push_back to add a new object to the vector a solution to this?

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• C++: getting the address of the start of an std::vector ?

  - by shoosh

  Sometimes it is useful to use the starting address of an std::vector and temporarily treat that address as the address of a regularly allocated buffer. For instance replace this: char* buf = new char[size]; fillTheBuffer(buf, size); useTheBuffer(buf, size); delete[] buf; With This: vector<char> buf(size); fillTheBuffer(&buf[0], size); useTheBuffer(&buf[0], size); The advantage of this is of course that the buffer is deallocated automatically and I don't have to worry about the delete[]. The problem I'm having with this is when size == 0. In that case the first version works ok. An empty buffer is "allocated" and the subsequent functions do nothing size they get size == 0. The second version however fails if size == 0 since calling buf[0] may rightly contain an assertion that 0 < size. So is there an alternative to the idiom &buf[0] that returns the address of the start of the vector even if the vector is empty? I've also considered using buf.begin() but according to the standard it isn't even guaranteed to return a pointer.

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