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  • OpenLayers: Get resolution of map in a given projection (4326)

    - by David Pfeffer
    I'm using OpenLayers to display OpenStreetMap maps. (Though, I'd assume this should be general enough to work for any map product...) I'm displaying some very sophisticated vector overlays, and the amount and resolution of the features I'm returning from the server via GeoJSON to overlay has proven too much for many computers. What I'd like to do now instead is to only send data befitting the resolution of the current zoom. This should be relatively easy to do using the getResolution and calculateBounds methods on the Map object. calculateBounds returns a Bounds object that then can be transformed between the map projection and display projection. How do I transform the resolution into my desired projection (4326 in this case)?

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  • List of functions references

    - by Ockonal
    Hello, I'm using boost::function for making references to the functions. Can I make a list of references? For example: boost::function<bool (Entity &handle)> behaviorRef; And I need in a list of such pointers. For example: std::vector<behaviorRef> listPointers; Of course it's wrong code due to behaviorRef isn't a type. So the question is: how can I store a list of pointers for the function?

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  • ingenious idea needed: how to declare different sizes for different fonts? @font-face?

    - by Haroldo
    I've never seen this done, but i get a feeling that there's gotta be a clever way of doing it. css font-size-adjust looks like it was never meant to be, but when i look around I'm seeing some really ingenious css techniques going on. Take this on nettuts yesterday for using @font-face for vector icons. my challenge: if(user has calibri ) { font-family: calibri; font-size: 12px; } if(user hasn't calibri ) { font-family: arial; font-size: 10px; }

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  • the problem only happens when i try create a release...

    - by ace
    I'm sorry if im not presenting this right, but i trully cannot understand what the problem is. i have a project to hand in, a code of 600 lines defined within a main, .cpp, and header file. if i compile the project with just a debugger and no release, it's fine. when i create it with the release, the following error occurs, for every function!!! 1st error: |36|multiple definition of `countLines(int&, std::vector const&)'| 2nd error: |36|first defined here| if someone will allow me and i can send them the entire code, that would be awesome - i have to have this done within 3 hours.

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  • Mono Ignores Graphics.InterpolationMode?

    - by Timothy Baldridge
    I have a program that draws some vector graphics using System.Drawing and the Graphics class. The anti-aliasing works, kindof okay, but for my need I neede oversampling, so I create the starting image to be n times larger and then scale back the final image by n. On Window and .NET the resulting image looks great! However, on Mono 2.4.2.3 (Ubuntu 9.10 stock install), the intropolation is horrible. Here's how I'm scaling my images: Bitmap bmp = new Bitmap(Bmp.Width / OverSampling, Bmp.Height / OverSampling); Graphics g = Graphics.FromImage(bmp); g.InterpolationMode = InterpolationMode.HighQualityBicubic; g.DrawImage(Bmp, 0, 0, bmp.Width, bmp.Height); g.Dispose(); From what I can tell there is no interpolation happening at all. Any ideas?

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  • Container for database-like searches

    - by Milan Babuškov
    I'm looking for some STL, boost, or similar container to use the same way indexes are used in databases to search for record using a query like this: select * from table1 where field1 starting with 'X'; or select * from table1 where field1 like 'X%'; I thought about using std::map, but I cannot because I need to search for fields that "start with" some text, and not those that are "equal to". I could create a sorted vector or list and use binary search (breaking the set in 2 in each step by reading the element in the middle and seeing if it's more or less than 'X'), but I wonder if there is some ready-made container I could use without reinventing the wheel?

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  • C++ boost ublas + units dimension constraints

    - by aaa
    hello. I am seeking advice on design/general idea on how to force matrix dimension constraints on ublas matrix/vector possibly using boost units. For example, let matrix A have dimensions of time x force (for example) // does not have dimensions, time x force and force x time are not distinguished. matrix<double> A; //something like? dimension<time, force, matrix<double> > A; dimension<force, time, matrix<double> > B = trans(A); have you done something like this or do you have some good idea about how to organize such constraints? Thank you

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  • Interpreter in C++: Function table storage problem

    - by sub
    In my interpreter I have built-in functions available in the language like print exit input, etc. These functions can obviously be accessed from inside the language. The interpreter then looks for the corresponding function with the right name in a vector and calls it via a pointer stored with its name. So I gather all these functions in files like io.cpp, string.cpp, arithmetic.cpp. But I have to add every function to the function list in the interpreter in order for it to be found. So in these function files I have things like: void print( arg ) { cout << arg.ToString; } I'd add this print function to the interpreter function list with: interpreter.AddFunc( "print", print ); But where should I call the interpreter.AddFunc? I can't just put it there below the print function as it has to be in a function according to the C++ syntax. Where and how should all the functions be added to the list?

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  • c++ library for endian-aware reading of raw file stream metadata?

    - by Kache4
    I've got raw data streams from image files, like: vector<char> rawData(fileSize); ifstream inFile("image.jpg"); inFile.read(&rawData[0]); I want to parse the headers of different image formats for height and width. Is there a portable library that can can read ints, longs, shorts, etc. from the buffer/stream, converting for endianess as specified? I'd like to be able to do something like: short x = rawData.readLeShort(offset); or long y = rawData.readBeLong(offset) An even better option would be a lightweight & portable image metadata library (without the extra weight of an image manipulation library) that can work on raw image data. I've found that Exif libraries out there don't support png and gif.

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  • Sorting by key > 10 integer sequences. with thrust

    - by smilingbuddha
    I want to perform a sort_by_key where I have a single key-sequence and multiple value sequences. One usually performs this with sort_by_key( key, key + N, make_zip_iterator( make_tuple(x1 , x2 , ...) ) ) However I want to perform a sort with 10 sequences each of length N. Thrust does not support tuples of size = 10. So is there a way around this ? Of course one can keep a separate copy of the key vector and perform sorts on bunches of 10 sequences. But I would like to do everything in a single call.

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  • Fast, Vectorizable method of taking floating point number modulus of special primes?

    - by caffiend
    Is there a fast method for taking the modulus of a floating point number? With integers, there are tricks for Mersenne primes, so that its possible to calculate y = x MOD 2^31 without needing division. Can any similar tricks be applied for floating point numbers? Preferably, in a way that can be converted into vector/SIMD operations, or moved into GPGPU code. The primes I'm interested in would be 2^7 and 2^31, although if there are more efficient ones for floating point numbers, those would be welcome.

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  • Problem overridding virtual function

    - by William
    Okay, I'm writing a game that has a vector of a pairent class (enemy) that s going to be filled with children classes (goomba, koopa, boss1) and I need to make it so when I call update it calls the childclasses respective update. I have managed to create a example of my problem. #include <stdio.h> class A{ public: virtual void print(){printf("Hello from A");} }; class B : public A{ public: void print(){printf("Hello from B");} }; int main(){ A ab = B(); ab.print(); while(true){} } Output wanted: "Hello from B" Output got: "Hello from A" How do I get it to call B's print function?

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  • How to make negate_unary work with any type?

    - by Chan
    Hi, Following this question: How to negate a predicate function using operator ! in C++? I want to create an operator ! can work with any functor that inherited from unary_function. I tried: template<typename T> inline std::unary_negate<T> operator !( const T& pred ) { return std::not1( pred ); } The compiler complained: Error 5 error C2955: 'std::unary_function' : use of class template requires template argument list c:\program files\microsoft visual studio 10.0\vc\include\xfunctional 223 1 Graphic Error 7 error C2451: conditional expression of type 'std::unary_negate<_Fn1>' is illegal c:\program files\microsoft visual studio 10.0\vc\include\ostream 529 1 Graphic Error 3 error C2146: syntax error : missing ',' before identifier 'argument_type' c:\program files\microsoft visual studio 10.0\vc\include\xfunctional 222 1 Graphic Error 4 error C2065: 'argument_type' : undeclared identifier c:\program files\microsoft visual studio 10.0\vc\include\xfunctional 222 1 Graphic Error 2 error C2039: 'argument_type' : is not a member of 'std::basic_ostream<_Elem,_Traits>::sentry' c:\program files\microsoft visual studio 10.0\vc\include\xfunctional 222 1 Graphic Error 6 error C2039: 'argument_type' : is not a member of 'std::basic_ostream<_Elem,_Traits>::sentry' c:\program files\microsoft visual studio 10.0\vc\include\xfunctional 230 1 Graphic Any idea? Update Follow "templatetypedef" solution, I got new error: Error 3 error C2831: 'operator !' cannot have default parameters c:\visual studio 2010 projects\graphic\graphic\main.cpp 39 1 Graphic Error 2 error C2808: unary 'operator !' has too many formal parameters c:\visual studio 2010 projects\graphic\graphic\main.cpp 39 1 Graphic Error 4 error C2675: unary '!' : 'is_prime' does not define this operator or a conversion to a type acceptable to the predefined operator c:\visual studio 2010 projects\graphic\graphic\main.cpp 52 1 Graphic Update 1 Complete code: #include <iostream> #include <functional> #include <utility> #include <cmath> #include <algorithm> #include <iterator> #include <string> #include <boost/assign.hpp> #include <boost/assign/std/vector.hpp> #include <boost/assign/std/map.hpp> #include <boost/assign/std/set.hpp> #include <boost/assign/std/list.hpp> #include <boost/assign/std/stack.hpp> #include <boost/assign/std/deque.hpp> struct is_prime : std::unary_function<int, bool> { bool operator()( int n ) const { if( n < 2 ) return 0; if( n == 2 || n == 3 ) return 1; if( n % 2 == 0 || n % 3 == 0 ) return 0; int upper_bound = std::sqrt( static_cast<double>( n ) ); for( int pf = 5, step = 2; pf <= upper_bound; ) { if( n % pf == 0 ) return 0; pf += step; step = 6 - step; } return 1; } }; /* template<typename T> inline std::unary_negate<T> operator !( const T& pred, typename T::argument_type* dummy = 0 ) { return std::not1<T>( pred ); } */ inline std::unary_negate<is_prime> operator !( const is_prime& pred ) { return std::not1( pred ); } template<typename T> inline void print_con( const T& con, const std::string& ms = "", const std::string& sep = ", " ) { std::cout << ms << '\n'; std::copy( con.begin(), con.end(), std::ostream_iterator<typename T::value_type>( std::cout, sep.c_str() ) ); std::cout << "\n\n"; } int main() { using namespace boost::assign; std::vector<int> nums; nums += 1, 3, 5, 7, 9; nums.erase( remove_if( nums.begin(), nums.end(), !is_prime() ), nums.end() ); print_con( nums, "After remove all primes" ); } Thanks, Chan Nguyen

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  • Matlab Question - Principal Component Analysis

    - by Jack
    I have a set of 100 observations where each observation has 45 characteristics. And each one of those observations have a label attached which I want to predict based on those 45 characteristics. So it's an input matrix with the dimension 45 x 100 and a target matrix with the dimension 1 x 100. The thing is that I want to know how many of those 45 characteristics are relevant in my set of data, basically the principal component analysis, and I understand that I can do this with Matlab function processpca. Could you please tell me how can I do this? Suppose that the input matrix is x with 45 rows and 100 columns and y is a vector with 100 elements.

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  • extraneous calls to copy-constructor and destructor

    - by eSKay
    [This question is a follow up to this question] class A { public: A() {cout<<"A Construction" <<endl;} A(A const& a){cout<<"A Copy Construction"<<endl;} ~A() {cout<<"A Destruction" <<endl;} }; int main() { { vector<A> t; t.push_back(A()); t.push_back(A()); // once more } } The output is: A Construction // 1 A Copy Construction // 1 A Destruction // 1 A Construction // 2 A Copy Construction // 2 A Copy Construction // WHY THIS? A Destruction // 2 A Destruction // deleting element from t A Destruction // deleting element from t A Destruction // WHY THIS?

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  • Multiset of shared_ptrs as a dynamic priority queue: Concept and practice

    - by Sarah
    I was using a vector-based priority queue typedef std::priority_queue< Event, vector< Event >, std::greater< Event > > EventPQ; to manage my Event objects. Now my simulation has to be able to find and delete certain Event objects not at the top of the queue. I'd like to know if my planned work-around can do what I need it to, and if I have the syntax right. I'd also like to know if dramatically better solutions exist. My plan is to make EventPQ a multiset of smart pointers to Event objects: typedef std::multi_set< boost::shared_ptr< Event > > EventPQ; I'm borrowing functions of the Event class from a related post on a multimap priority queue. // Event.h #include <cstdlib> using namespace std; #include <set> #include <boost/shared_ptr.hpp> class Event; typedef std::multi_set< boost::shared_ptr< Event > > EventPQ; class Event { public: Event( double t, int eid, int hid ); ~Event(); void add( EventPQ& q ); void remove(); bool operator < ( const Event & rhs ) const { return ( time < rhs.time ); } bool operator > ( const Event & rhs ) const { return ( time > rhs.time ); } double time; int eventID; int hostID; EventPQ* mq; EventPQ::iterator mIt; }; // Event.cpp Event::Event( double t, int eid, int hid ) { time = t; eventID = eid; hostID = hid; } Event::~Event() {} void Event::add( EventPQ& q ) { mq = &q; mIt = q.insert( boost::shared_ptr<Event>(this) ); } void Event::remove() { mq.erase( mIt ); mq = 0; mIt = EventPQ::iterator(); } I was hoping that by making EventPQ a container of pointers, I could avoid wasting time copying Events into the container and avoid accidentally editing the wrong copy. Would it be dramatically easier to store the Events themselves in EventPQ instead? Does it make more sense to remove the time keys from Event objects and use them instead as keys in a multimap? Assuming the current implementation seems okay, my questions are: Do I need to specify how to sort on the pointers, rather than the objects, or does the multiset automatically know to sort on the objects pointed to? If I have a shared_ptr ptr1 to an Event that also has a pointer in the EventPQ container, how do I find and delete the corresponding pointer in EventPQ? Is it enough to .find( ptr1 ), or do I instead have to find by the key (time)? Is the Event::remove() sufficient for removing the pointer in the EventPQ container? There's a small chance multiple events could be created with the same time (obviously implied in the use of multiset). If the find() works on event times, to avoid accidentally deleting the wrong event, I was planning to throw in a further check on eventID and hostID. Does this seem reasonable? (Dumb syntax question) In Event.h, is the declaration of dummy class Event;, then the EventPQ typedef, and then the real class Event declaration appropriate? I'm obviously an inexperienced programmer with very spotty background--this isn't for homework. Would love suggestions and explanations. Please let me know if any part of this is confusing. Thanks.

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  • problems with matlab wavrecord and wavread

    - by user504363
    Hi all I have a problem in matlab I want to record a speech for 2 seconds then read the recorded sound and plot it I use the code FS = 8000; new_wav = wavrecord(2*FS,FS,'int16'); x = wavread(new_wav); plot(x); but the error appears ??? Error using ==> fileparts at 20 Input must be a row vector of characters. Error in ==> wavread>open_wav at 193 [pat,nam,ext] = fileparts(file); Error in ==> wavread at 65 [fid,msg] = open_wav(file); Error in ==> test at 2 x = wavread(new_wav); I plotted correctly recorded sound files, but when I want to record new one through matlab I get this errors. I tried many ways by changing FS and 'int16' but nothing happens. thanks

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  • Can I write functors using a private nested struct?

    - by Kristo
    Given this class: class C { private: struct Foo { int key1, key2, value; }; std::vector<Foo> fooList; }; The idea here is that fooList can be indexed by either key1 or key2 of the Foo struct. I'm trying to write functors to pass to std::find so I can look up items in fooList by each key. But I can't get them to compile because Foo is private within the class (it's not part of C's interface). Is there a way to do this without exposing Foo to the rest of the world? (note: I've got to run to a meeting. I'll be able to post more sample code in about a half hour.)

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  • How might I assume a "default value" when parsing using boost::spirit?

    - by tJener
    Let's say I have a grammar defined to something like: a b c d where c, and d are optional and default to 14 if not given. Can I get it to automatically return the 14 if the value isn't given? The closest I've come is like the following: qi::rule<Iterator, std::vector<int>(), ascii::space_type> some_rule; some_rule %= >> int_ >> int_ >> -int_ >> -int_; // ... some_other_rule = some_rule[&some_callback_for_int_vectors]; which will then get 0 for the optional values that didn't show up (I believe). I then change consecutive 0s at the end into 14. Not only is this horribly wrong, but its also just not elegant. Is there a better way to do this?

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  • How to interpolate rotations?

    - by uhuu
    I have two vectors describing rotations; a start rotation A and a target rotation B. How would I best go about interpolating A by a factor F to approach B? Using a simple lerp on the vectors fails to work when more than one dimension needs to be interpolated (i.e. produces undesirable rotations). Maybe building quaternions from the rotation vectors and using slerp is the way to go. But how, then, could I extract a vector describing the new rotation from the resulting quaternion? Thanks in advance.

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  • Uniform distribution of binary values in Matlab

    - by JohnIdol
    I have a requirement for the generation of a given number N of vectors of given size each consistent of a uniform distribution of 0s and 1s. This is what I am doing at the moment, but I noticed that the distribution is strongly peaked at half 1s and half 0s, which is no good for what I am doing: a = randint(1, sizeOfVector, [0 1]); The unifrnd function looks promising for what I need, but I can't manage to understand how to output a binary vector of that size. Is it the case that I can use the unifrnd function (and if so how would be appreciated!) or can is there any other more convenient way to obtain such a set of vectors? Any help appreciated!

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  • WPF tabswitch/ render takes too much time..

    - by Socrates
    I have a WPF application with many tabs.. in one tab.. i make a verycomplex vector drawing consisting of thousands of drawing visuals.. (this represents a machine and all elements need to be interactable..) It takes 3/4 seconds for drawing this for the first time..After the first draw it should be done.. The problem is if i switch to another tab and comeback, it takes atlease 2,3 seconds to show the tabpage with drawing again.. Since there is no redraw, why should it take so much time..?

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  • Distance between hyperplanes

    - by michael dillard
    I'm trying to teach myself some machine learning, and have been using the MNIST database (http://yann.lecun.com/exdb/mnist/) do so. The author of that site wrote a paper in '98 on all different kinds of handwriting recognition techniques, available at http://yann.lecun.com/exdb/publis/pdf/lecun-98.pdf. The 10th method mentioned is a "Tangent Distance Classifier". The idea being that if you place each image in a (NxM)-dimensional vector space, you can compute the distance between two images as the distance between the hyperplanes formed by each where the hyperplane is given by taking the point, and rotating the image, rescaling the image, translating the image, etc. I can't figure out enough to fill in the missing details. I understand that most of these are indeed linear operators, so how does one use that fact to then create the hyperplane? And once we have a hyperplane, how do we take its distance with other hyperplanes?

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  • RODBC string getting truncated

    - by sayan dasgupta
    Hi all, I am fetching data from MySql Server into R using RODBC. So in one column of the database is a character vector SELECT MAX(CHAR_LENGTH(column)) FROM reqtable; RETURNS 26566 Now I will show you an example how I am running into the problem `library(RODBC) con <- odbcConnect("mysqlcon") rslts <- as.numeric(sqlQuery(con, "SELECT CHAR_LENGTH(column) FROM reqtable LIMIT 10", as.is=TRUE)[,1]) ` returns > rslts [1] 62 31 17 103 30 741 28 73 25 357 where as rslts <- nchar(as.character(sqlQuery(con, "SELECT column FROM reqtable LIMIT 10", as.is=TRUE)[,1])) returns > rslts [1] 62 31 17 103 30 255 28 73 25 255 So strings with length 255 is getting truncated at 255. Is there a way I can get the full string. Thanks

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  • Multiplying Block Matrices in Numpy

    - by Ada Xu
    Hi Everyone I am python newbie I have to implement lasso L1 regression for a class assignment. This involves solving a quadratic equation involving block matrices. minimize x^t * H * x + f^t * x where x 0 Where H is a 2 X 2 block matrix with each element being a k dimensional matrix and x and f being a 2 X 1 vectors each element being a k dimension vector. I was thinking of using nd arrays. such that np.shape(H) = (2, 2, k, k) np.shape(x) = (2, k) But I figured out that np.dot(X, H) doesn't work here. Is there an easy way to solve this problem? Thanks in advance.

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