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  • How do I put a vector inside of a struct in Go?

    - by Brian T Hannan
    I'm trying to put a vector variable inside a struct in Google's Go programming language. This is what I have so far: Want: type Point struct { x, y int } type myStruct struct { myVectorInsideStruct vector; } func main(){ myMyStruct := myStruct{vector.New(0)}; myPoint := Point{2,3}; myMyStruct.myVectorInsideStruct.Push(myPoint); } Have: type Point struct { x, y int } func main(){ myVector := vector.New(0); myPoint := Point{2,3}; myVector.Push(myPoint); } I can get the vector to work in my main function just fine, but I want to encapsulate it inside a struct for easier use.

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  • Pointing class property to another class with vectors

    - by jmclem
    I've got a simple class, and another class that has a property that points to the first class: #include <iostream> #include <vector> using namespace std; class first{ public: int var1; }; class second{ public: first* classvar; }; Then, i've got a void that's supposed to point "classvar" to the intended iteration of the class "first". void fill(vector<second>& sec, vector<first>& fir){ sec[0].classvar = &fir[0]; } Finally the main(). Create and fill a vector of class "first", create "second" vector, and run the fill function. int main(){ vector<first> a(1); a[0].var1 = 1000; vector<second> b(1); fill(b, a); cout << b[0].classvar.var1 << '\n'; system("PAUSE"); return 0; } This gives me the following error: 1>c:\...\main.cpp(29) : error C2228: left of '.var1' must have class/struct/union 1> type is 'first *' And I can't figure out why it reads the "classvar" as the whole vector instead of just the single instance. Should I do this cout << b[0].classvar[0].var1 << '\n'; it reads perfectly. Can anyone figure out the problem? Thanks in advance

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  • C++ Vector of vectors is messing with me

    - by xbonez
    If I put this code in a .cpp file and run it, it runs just fine: #include <iostream> #include <vector> #include <string> using namespace std; typedef vector<int> row; typedef vector<row> myMatrix; void main() { //cout << endl << "test" << endl; myMatrix mat(2,2); mat[0][1] = 2; cout << endl << mat[0][1] << endl; } But, if I make a .h and a .cpp file with the .h file like this, it gives me boatloads of errors. #ifndef _grid_ #define _grid_ #include<iostream> #include<vector> #include<string> using namespace std; typedef vector<int> row; typedef vector<row> myMatrix; class grid { public: grid(); ~grid(); int getElement(unsigned int ri, unsigned int ci); bool setElement(unsigned int ri, unsigned int ci, unsigned int value); private: myMatrix sudoku_(9,9); }; #endif These are some of the errors I get: warning C4091: 'typedef ' : ignored on left of 'int' when no variable is declared error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

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  • C++ Memory allocation question involving vectors

    - by TheFuzz
    vector< int > vect; int *int_ptr = new int(10); vect.push_back( *int_ptr ); I under stand that every "new" needs to be followed by a "delete" at some point but does the clear() method clean this memory? What about this method of doing the same thing: vector< int > vect; int int_var = 10; vect.push_back( int_var ); From what I understand, clear() calls the variables destructors, but both vect.push_back() methods in this example push an object on the vector, not a pointer. so does the first example using an int pointer need something other than clear() to clean up memory?

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  • C++ iterators problem

    - by qwead
    I'm working with iterators on C++ and I'm having some trouble here. It says "Debug Assertion Failed" on expression (this-_Has_container()) on line interIterator++. Distance list is a vector< vector< DistanceNode . What I'm I doing wrong? vector< vector<DistanceNode> >::iterator externIterator = distanceList.begin(); while (externIterator != distanceList.end()) { vector<DistanceNode>::iterator interIterator = externIterator->begin(); while (interIterator != externIterator->end()){ if (interIterator->getReference() == tmp){ //remove element pointed by interIterator externIterator->erase(interIterator); } // if interIterator++; } // while externIterator++; } // while

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  • Scaling vectors from a center point?

    - by user146780
    I'm trying to figure out if I have points that make for example a square: * * * * and let's say I know the center of this square. I want a formula that will make it for eample twice its size but from the center * * * * * * * * Therefore the new shape is twice as large and from the center of the polygon. It has to work for any shape not just squares. I'm looking more for the theory behind it more than the implementation. Thanks

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  • C++ Vector of vectors

    - by xbonez
    I have a class header file called Grid.h that contains the following 2 private data object: vector<int> column; vector<vector<int>> row; And a public method whose prototype in Grid.h is such: int getElement (unsigned int& col, unsigned int& row); The definition of above mentioned function is defined as such in Grid.cpp: int getElement (unsigned int& col, unsigned int& row) { return row[row][col] ; } When I run the program, I get this error: error C2109: subscript requires array or pointer type Whats going wrong?

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  • R: optimal way of computing the "product" of two vectors

    - by Musa
    Hi, Let's assume that I have a vector r <- rnorm(4) and a matrix W of dimension 20000*200 for example: W <- matrix(rnorm(20000*200),20000,200) I want to compute a new matrix M of dimension 5000*200 such that m11 <- r%*%W[1:4,1], m21 <- r%*%W[5:8,1], m12 <- r%*%W[1:4,2] etc. (i.e. grouping rows 4-by-4 and computing the product). What's the optimal (speed,memory) way of doing this? Thanks in advance.

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  • hash tables and 2d vectors

    - by Sunil
    I want to push a 2d vector into a hash table row by row and later search for a row (vector) in the hash table and want to be able to find it. I want to do something like #include <iostream> #include <set> #include <vector> using namespace std; int main(){ std::set < vector<int> > myset; vector< vector<int> > v; int k = 0; for ( int i = 0; i < 5; i++ ) { v.push_back ( vector<int>() ); for ( int j = 0; j < 5; j++ ) v[i].push_back ( k++ ); } for ( int i = 0; i < 5; i++ ) { std::copy(v[i].begin(),v[i].end(),std::inserter(myset)); // This is not correct but what is the right way ? // and also here, I want to search for a particular vector if it exists in the table. for ex. the second row of vector v. } return 0; } I'm not sure how to insert and look up a vector in a set. So if nybody could guide me, it will be helpful. Thanks

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  • How to compare two vectors, in C++

    - by Vincenzo
    This is my code: #include <algorithm> void f() { int[] a = {1, 2, 3, 4}; int[] b = {1, 2, 100, 101}; // I want to do something like this: // int* found = compare(a[0], a[3], b[0]); // in order to get a pointer to a[2] } Maybe I missed this algorithm in the manual… Please help :)

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  • accessing a vector from the back

    - by Faken
    Is there a way to access an element on a vector starting from the back? I want to access the second last element.currently I'm using the following to achieve that: myVector[myVector.size() - 2] but this seems slow and clunky, is there a better way?

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  • Scipy Negative Distance? What?

    - by disappearedng
    I have a input file which are all floating point numbers to 4 decimal place. i.e. 13359 0.0000 0.0000 0.0001 0.0001 0.0002` 0.0003 0.0007 ... (the first is the id). My class uses the loadVectorsFromFile method which multiplies it by 10000 and then int() these numbers. On top of that, I also loop through each vector to ensure that there are no negative values inside. However, when I perform _hclustering, I am continually seeing the error, "Linkage Z contains negative values". I seriously think this is a bug because: I checked my values, the values are no where small enough or big enough to approach the limits of the floating point numbers and the formula that I used to derive the values in the file uses absolute value (my input is DEFINITELY right). Can someone enligten me as to why I am seeing this weird error? What is going on that is causing this negative distance error? ===== def loadVectorsFromFile(self, limit, loc, assertAllPositive=True, inflate=True): """Inflate to prevent "negative" distance, we use 4 decimal points, so *10000 """ vectors = {} self.winfo("Each vector is set to have %d limit in length" % limit) with open( loc ) as inf: for line in filter(None, inf.read().split('\n')): l = line.split('\t') if limit: scores = map(float, l[1:limit+1]) else: scores = map(float, l[1:]) if inflate: vectors[ l[0]] = map( lambda x: int(x*10000), scores) #int might save space else: vectors[ l[0]] = scores if assertAllPositive: #Assert that it has no negative value for dirID, l in vectors.iteritems(): if reduce(operator.or_, map( lambda x: x < 0, l)): self.werror( "Vector %s has negative values!" % dirID) return vectors def main( self, inputDir, outputDir, limit=0, inFname="data.vectors.all", mappingFname='all.id.features.group.intermediate'): """ Loads vector from a file and start clustering INPUT vectors is { featureID: tfidfVector (list), } """ IDFeatureDic = loadIdFeatureGroupDicFromIntermediate( pjoin(self.configDir, mappingFname)) if not os.path.exists(outputDir): os.makedirs(outputDir) vectors = self.loadVectorsFromFile( limit, pjoin( inputDir, inFname)) for threshold in map( lambda x:float(x)/30, range(20,30)): clusters = self._hclustering(threshold, vectors) if clusters: outputLoc = pjoin(outputDir, "threshold.%s.result" % str(threshold)) with open(outputLoc, 'w') as outf: for clusterNo, cluster in clusters.iteritems(): outf.write('%s\n' % str(clusterNo)) for featureID in cluster: feature, group = IDFeatureDic[featureID] outline = "%s\t%s\n" % (feature, group) outf.write(outline.encode('utf-8')) outf.write("\n") else: continue def _hclustering(self, threshold, vectors): """function which you should call to vary the threshold vectors: { featureID: [ tfidf scores, tfidf score, .. ] """ clusters = defaultdict(list) if len(vectors) > 1: try: results = hierarchy.fclusterdata( vectors.values(), threshold, metric='cosine') except ValueError, e: self.werror("_hclustering: %s" % str(e)) return False for i, featureID in enumerate( vectors.keys()):

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  • Creating an OpenGL FPS camera: I have the position and orientation vectors, now what?

    - by Synthetix
    I have been struggling to create a first person camera in OpenGL ES 2.0 without using gluLookAt(). I grab the camera's orientation vectors (the way it's looking) from the current modelview matrix, and use that to calculate the new forward/backward (Z) translation value. I then calculate the strafe (X) value from the dot product of Z and Y (which is always 1.0). So, I have all the information I need to create a view matrix, but how do I do that without using gluLookAt? Almost all the examples I've seen use gluLookAt, but no such function exists in OpenGL ES 2.0. Besides, one of the moderators on cprogramming.com mentioned that gluLookAt is not appropriate for FPS cameras: http://cboard.cprogramming.com/game-programming/135390-how-properly-move-strafe-yaw-pitch-camera-opengl-glut-using-glulookat.html I am really confused by all the conflicting information I'm getting. I just want to create a first person camera that goes forward (W,S keys), side-to-side (A,D keys) and rotates around its center (Y axis only), Wolfenstein style. Any help on this would be much appreciated!

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  • Why does Clojure hang after hacing performed my calculations?

    - by Thomas
    Hi all, I'm experimenting with filtering through elements in parallel. For each element, I need to perform a distance calculation to see if it is close enough to a target point. Never mind that data structures already exist for doing this, I'm just doing initial experiments for now. Anyway, I wanted to run some very basic experiments where I generate random vectors and filter them. Here's my implementation that does all of this (defn pfilter [pred coll] (map second (filter first (pmap (fn [item] [(pred item) item]) coll)))) (defn random-n-vector [n] (take n (repeatedly rand))) (defn distance [u v] (Math/sqrt (reduce + (map #(Math/pow (- %1 %2) 2) u v)))) (defn -main [& args] (let [[n-str vectors-str threshold-str] args n (Integer/parseInt n-str) vectors (Integer/parseInt vectors-str) threshold (Double/parseDouble threshold-str) random-vector (partial random-n-vector n) u (random-vector)] (time (println n vectors (count (pfilter (fn [v] (< (distance u v) threshold)) (take vectors (repeatedly random-vector)))))))) The code executes and returns what I expect, that is the parameter n (length of vectors), vectors (the number of vectors) and the number of vectors that are closer than a threshold to the target vector. What I don't understand is why the programs hangs for an additional minute before terminating. Here is the output of a run which demonstrates the error $ time lein run 10 100000 1.0 [null] 10 100000 12283 [null] "Elapsed time: 3300.856 msecs" real 1m6.336s user 0m7.204s sys 0m1.495s Any comments on how to filter in parallel in general are also more than welcome, as I haven't yet confirmed that pfilter actually works.

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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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  • signed angle between two 3d vectors with same origin within the same plane? recipe?

    - by Advanced Customer
    Was looking through the web for an answer but it seems like there is no clear recipe for it. What I need is a signed angle of rotation between two vectors Va and Vb lying within the same 3D plane and having the same origin knowing that: the plane contatining both vectors is an arbitrary and is not parallel to XY or any other of cardinal planes Vn - is a plane normal both vectors along with the normal have the same origin O = { 0, 0, 0 } Va - is a reference for measuring the left handed rotation at Vn The angle should be measured in such a way so if the plane would be XY plane the Va would stand for X axis unit vector of it. I guess I should perform a kind of coordinate space transformation by using the Va as the X-axis and the cross product of Vb and Vn as the Y-axis and then just using some 2d method like with atan2() or something. Any ideas? Formulas?

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  • What are the attack vectors for passwords sent over http?

    - by KevinM
    I am trying to convince a customer to pay for SSL for a web site that requires login. I want to make sure I correctly understand the major scenarios in which someone can see the passwords that are being sent. My understanding is that at any of the hops along the way can use a packet analyzer to view what is being sent. This seems to require that any hacker (or their malware/botnet) be on the same subnet as any of the hops the packet takes to arrive at its destination. Is that right? Assuming some flavor of this subnet requirement holds true, do I need to worry about all the hops or just the first one? The first one I can obviously worry about if they're on a public Wifi network since anyone could be listening in. Should I be worried about what's going on in subnets that packets will travel across outside this? I don't know a ton about network traffic, but I would assume it's flowing through data centers of major carriers and there's not a lot of juicy attack vectors there, but please correct me if I am wrong. Are there other vectors to be worried about outside of someone listening with a packet analyzer? I am a networking and security noob, so please feel free to set me straight if I am using the wrong terminology in any of this.

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  • KD-Trees and missing values (vector comparison)

    - by labratmatt
    I have a system that stores vectors and allows a user to find the n most similar vectors to the user's query vector. That is, a user submits a vector (I call it a query vector) and my system spits out "here are the n most similar vectors." I generate the similar vectors using a KD-Tree and everything works well, but I want to do more. I want to present a list of the n most similar vectors even if the user doesn't submit a complete vector (a vector with missing values). That is, if a user submits a vector with three dimensions, I still want to find the n nearest vectors (stored vectors are of 11 dimensions) I have stored. I have a couple of obvious solutions, but I'm not sure either one seem very good: Create multiple KD-Trees each built using the most popular subset of dimensions a user will search for. That is, if a user submits a query vector of thee dimensions, x, y, z, I match that query to my already built KD-Tree which only contains vectors of three dimensions, x, y, z. Ignore KD-Trees when a user submits a query vector with missing values and compare the query vector to the vectors (stored in a table in a DB) one by one using something like a dot product. This has to be a common problem, any suggestions? Thanks for the help.

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  • How to use Pixel Bender (pbj) in ActionScript3 on large Vectors to make fast calculations?

    - by Arthur Wulf White
    Remember my old question: 2d game view camera zoom, rotation & offset using 'Filter' / 'Shader' processing? I figured I could use a Pixel Bender Shader to do the computation for any large group of elements in a game to save on processing time. At least it's a theory worth checking. I also read this question: Pass large array to pixel shader Which I'm guessing is about accomplishing the same thing in a different language. I read this tutorial: http://unitzeroone.com/blog/2009/03/18/flash-10-massive-amounts-of-3d-particles-with-alchemy-source-included/ I am attempting to do some tests. Here is some of the code: private const SIZE : int = Math.pow(10, 5); private var testVectorNum : Vector.<Number>; private function testShader():void { shader.data.ab.value = [1.0, 8.0]; shader.data.src.input = testVectorNum; shader.data.src.width = SIZE/400; shader.data.src.height = 100; shaderJob = new ShaderJob(shader, testVectorNum, SIZE / 4, 1); var time : int = getTimer(), i : int = 0; shaderJob.start(true); trace("TEST1 : ", getTimer() - time); } The problem is that I keep getting a error saying: [Fault] exception, information=Error: Error #1000: The system is out of memory. Update: I managed to partially workaround the problem by converting the vector into bitmapData: (Using this technique I still get a speed boost of 3x using Pixel Bender) private function testShader():void { shader.data.ab.value = [1.0, 8.0]; var time : int = getTimer(), i : int = 0; testBitmapData.setVector(testBitmapData.rect, testVectorInt); shader.data.src.input = testBitmapData; shaderJob = new ShaderJob(shader, testBitmapData); shaderJob.start(true); testVectorInt = testBitmapData.getVector(testBitmapData.rect); trace("TEST1 : ", getTimer() - time); }

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  • Python - How to find a correlation between two vectors ?

    - by psihodelia
    Given two vectors X and Y I have to find their correlation, i.e. their linear dependence/independence. Both vectors have equal dimension. A resulted answer should be a floating point number from [-1.0 .. 1.0]. Example: X=[-1, 2, 0] Y=[ 4, 2, -0.3] Find y=cor(X,Y) such that y belongs to [-1.0 .. 1.0]. It should be a simple construction involving a list-comprehension. No external library is allowed. UPDATE: ok, if dot product is enough, then here is my solution: nX = 1/(sum([x*x for x in X]) ** 0.5) nY = 1/(sum([y*y for y in Y]) ** 0.5) cor = sum([(x*nX)*(y*nY) for x,y in zip(X,Y) ]) right?

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  • How to resize a group of vectors in Expression Blend/WPF/Silverlight ?

    - by Shnitzel
    So say for example I created a few small squares in expression blend. I then group them together by selecting them, right clicking and selecting "Group Into - Grid" So now that they are in the grid, I'd like to be able to resize this grid and then they would resize but it doesn't happen, it just resizes the grid but leaves the vectors the same. Is there a way to do what I am looking for? p.s I know you can just select all the vectors and then resize them all, but I am looking for a way to just resize one container and not all the objects in there..

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  • What are the attack vectors for passwords sent over http?

    - by KevinM
    I am trying to convince a customer to pay for SSL for a web site that requires login. I want to make sure I correctly understand the major scenarios in which someone can see the passwords that are being sent. My understanding is that at any of the hops along the way can use a packet analyzer to view what is being sent. This seems to require that any hacker (or their malware/botnet) be on the same subnet as any of the hops the packet takes to arrive at its destination. Is that right? Assuming some flavor of this subnet requirement holds true, do I need to worry about all the hops or just the first one? The first one I can obviously worry about if they're on a public Wifi network since anyone could be listening in. Should I be worried about what's going on in subnets that packets will travel across outside this? I don't know a ton about network traffic, but I would assume it's flowing through data centers of major carriers and there's not a lot of juicy attack vectors there, but please correct me if I am wrong. Are there other vectors to be worried about outside of someone listening with a packet analyzer? I am a networking and security noob, so please feel free to set me straight if I am using the wrong terminology in any of this.

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  • Fluent NHibernate mapping List<Point> as value to single column

    - by Paja
    I have this class: public class MyEntity { public virtual int Id { get; set; } public virtual List<Point> Vectors { get; set; } } How can I map the Vectors in Fluent NHibernate to a single column (as value)? I was thinking of this: public class Vectors : ISerializable { public List<Point> Vectors { get; set; } /* Here goes ISerializable implementation */ } public class MyEntity { public virtual int Id { get; set; } public virtual Vectors Vectors { get; set; } } Is it possible to map the Vectors like this, hoping that Fluent NHibernate will initialize Vectors class as standard ISerializable? Or how else could I map List<Point> to a single column? I guess I will have to write the serialization/deserialization routines myself, which is not a problem, I just need to tell FNH to use those routines. I guess I should use IUserType or ICompositeUserType, but I have no idea how to implement them, and how to tell FNH to cooperate.

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  • Why is there no way to resize SRFI-4 vectors in Scheme?

    - by Jay
    I see that SRFI 4 does not mention resizing of vectors. I'm using f64vectors (for which I need fast access), and I'd like to be able to resize them quickly (similar to what realloc does in C), and not necessarily copy the whole vector. Since I didn't find any references to a "resize-f64vector" procedure, I'd like to know why it doesn't exist (and if making a new vector and copying over is my only option).

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