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• I need help on this data file to be edited in SOM_PAK format

  - by Mola

  Hi Experts, I am working on Self Organizing Map (SOM) Implementation and i have a microarray dataset which i am trying to read in using some_read_data function, but i keep having an errors when i edit it to have it in SOM_PAK form which is recognise by SOM for reading such as ??? Error using == somtoolbox\som_read_data.m Only 69 vector components on input file data line 1 (dimension is 70) Error in == SomMainFunction at 3 sD = som_read_data('B_r2.txt'); but when i try to read the data without editing which is the original file as shown here: http://rapidshare.com/files/376239367/DLBCL.txt.html It indicates "Data read OK", but i have the following error ??? Error using == unknown Out of memory. Type HELP MEMORY for your options. Error in == somtoolbox\som_bmus.m at 189 Bmus = zeros(dlen,length(which_bmus)); Error in == somvis\somvis_p_matrix.m at 41 [dummy dists] = som_bmus (dat, dat, 2:datlen); Error in == SomMainFunction at 16 [pheight rad_real perc] = somvis_p_matrix(sM,sD); You can get the datafile from here:http://rapidshare.com/files/376239367/DLBCL.txt.html I need someone to help me correct this data for me and put it in SOM_PAK format. I have tried getting it in SOM_PAK format, but it still giving me errors:

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• Wrapping unmanaged C++ with C++/CLI - a proper approach.

  - by Jamie

  Hi there, as stated in the title, I want to have my old C++ library working in managed .NET. I think of two possibilities: 1) I might try to compile the library with /clr and try "It Just Works" approach. 2) I might write a managed wrapper to the unmanaged library. First of all, I want to have my library working FAST, as it was in unmanaged environment. Thus, I am not sure if the first approach will not cause a large decrease in performance. However, it seems to be faster to implement (not a right word :-)) (assuming it will work for me). On the other hand, I think of some problems that might appear while writing a wrapper (e.g. how to wrap some STL collection (vector for instance)?) I think of writing a wrapper residing in the same project as the unmanaged C++ resides - is that a reasonable approach (e.g. MyUnmanagedClass and MyManagedClass in the same project, the second wrapping the other)? What would you suggest in that problem? Which solution is going to give me better performance of the resulting code? Thank you in advance for any suggestions and clues! Cheers

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• iPhone --- 3DES Encryption returns "wrong" results?

  - by Jan Gressmann

  Hello fellow developers, I have some serious trouble with a CommonCrypto function. There are two existing applications for BlackBerry and Windows Mobile, both use Triple-DES encryption with ECB mode for data exchange. On either the encrypted results are the same. Now I want to implent the 3DES encryption into our iPhone application, so I went straight for CommonCrypto: http://www.opensource.apple.com/source/CommonCrypto/CommonCrypto-32207/CommonCrypto/CommonCryptor.h I get some results if I use CBC mode, but they do not correspond with the results of Java or C#. Anyway, I want to use ECB mode, but I don't get this working at all - there is a parameter error showing up... This is my call for the ECB mode... I stripped it a little bit: const void *vplainText; plainTextBufferSize = [@"Hello World!" length]; bufferPtrSize = (plainTextBufferSize + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1); plainText = (const void *) [@"Hello World!" UTF8String]; NSString *key = @"abcdeabcdeabcdeabcdeabcd"; ccStatus = CCCrypt(kCCEncrypt, kCCAlgorithm3DES, kCCOptionECBMode, key, kCCKeySize3DES, nil, // iv, not used with ECB plainText, plainTextBufferSize, (void *)bufferPtr, // output bufferPtrSize, &movedBytes); t is more or less the code from here: http://discussions.apple.com/thread.jspa?messageID=9017515 But as already mentioned, I get a parameter error each time... When I use kCCOptionPKCS7Padding instead of kCCOptionECBMode and set the same initialization vector in C# and my iPhone code, the iPhone gives me different results. Is there a mistake by getting my output from the bufferPtr? Currently I get the encrypted stuff this way: NSData *myData = [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes]; result = [[NSString alloc] initWithData:myData encoding:NSISOLatin1StringEncoding]; It seems I almost tried every setting twice, different encodings and so on... where is my error?

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• How to use boost::fusion::transform on heterogeneous containers?

  - by Kyle

  Boost.org's example given for fusion::transform is as follows: struct triple { typedef int result_type; int operator()(int t) const { return t * 3; }; }; // ... assert(transform(make_vector(1,2,3), triple()) == make_vector(3,6,9)); Yet I'm not "getting it." The vector in their example contains elements all of the same type, but a major point of using fusion is containers of heterogeneous types. What if they had used make_vector(1, 'a', "howdy") instead? int operator()(int t) would need to become template<typename T> T& operator()(T& const t) But how would I write the result_type? template<typename T> typedef T& result_type certainly isn't valid syntax, and it wouldn't make sense even if it was, because it's not tied to the function.

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• 2D platformer gravity physics with slow-motion

  - by DD

  Hi all, I fine tuned my 2d platformer physics and when I added slow-motion I realized that it is messed up. The problem I have is that for some reason the physics still depends on framerate. So when I scale down time elapsed, every force is scaled down as well. So the jump force is scaled down, meaning in slow-motion, character jumps vertically smaller height and gravity force is scaled down as well so the character goes further in the air without falling. I'm sending update function in hopes that someone can help me out here (I separated vertical (jump, gravity) and walking (arbitrary walking direction on a platform - platforms can be of any angle) vectors): characterUpdate:(float)dt { //Compute walking velocity walkingAcceleration = direction of platform * walking acceleration constant * dt; initialWalkingVelocity = walkingVelocity; if( isWalking ) { if( !isJumping ) walkingVelocity = walkingVelocity + walkingAcceleration; else walkingVelocity = walkingVelocity + Vector( walking acceleration constant * dt, 0 ); } // Compute jump/fall velocity if( !isOnPlatform ) { initialVerticalVelocity = verticalVelocity; verticalVelocity = verticalVelocity + verticalAcceleration * dt; } // Add walking velocity position = position + ( walkingVelocity + initialWalkingVelocity ) * 0.5 * dt; //Add jump/fall velocity if not on a platform if( !isOnPlatform ) position = position + ( verticalVelocity + initialVerticalVelocity ) * 0.5 * dt; verticalAcceleration.y = Gravity * dt; }

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• Storing header and data sections in a CSV file

  - by morpheous

  This should be relatively easy to do, but after several hours straight programming my mind seems a bit frazzled and could do with some help. I have a C++ class which I am currently using to store read/write data to file. I was initially using binary data, but have decided to store the data as CSV in order to let programs written in other languages be able to load the data. The C++ class looks a bit like this: class BinaryData { public: BinaryData(); void serialize(std::ostream& output) const; void deserialize(std::istream& input); private: Header m_hdr; std::vector<Row> m_rows; }; I am simply rewriting the serialize/deserialize methods to write to a CSV file. I am not sure on the "best" way to store a header section and a "data" section in a "flat" CSV file though - any suggestions on the most sensible way to do this?

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• JTable data only shown after scrolling

  - by Christian 'fuzi' Orgler

  I wrote a method, that creates my DefaultTableModel and there I'm going to add my records. When I set the model to my JTable, the data rows are blank. After scrolling the data gets displayed correct. How can I avoid this and display the data from the first moment? EDIT: I imported the javax.swing.table.DefaultTableModel -- is this correct? private DefaultTableModel _dtm; private void loadTable(Vector<Member> members) { loadTableModel(); try { lbl_state.setText("Please wait"); for (Member actMember : members) { String gender = ""; if (actMember.getGender() == MemberView.MEMBER_MALE) { gender = "männlich"; } else { gender = "weiblich"; } _dtm.addRow(new Object[]{ actMember.getNname(), actMember.getVname(), actMember.getCity(), actMember.getStreet(), actMember.getPlz(), actMember.getMail(), actMember.getPhonenumber(), actMember.getBirthdayString(), actMember.getStartDateString(), gender, actMember.getBankname(), actMember.getAccountnumber(), actMember.getBanknumber(), actMember.getGroup().toString(), (actMember.hasAccess() ? "JA" : "NEIN"), actMember.getWriteDateString(), (actMember.hasDrinkAbo() ? "JA" : "NEIN") }); } } catch (Exception ex) { System.err.println(ex.getMessage()); } tbl_results.setModel(_dtm); } private void loadTableModel() { _dtm = new DefaultTableModel(new Object[]{"Nachname", "Vorname", "Ort", "Straße", "PLZ", "E-Mail", "Telefon", "Geburtsdatum", "Beitrittsdatum", "Geschlecht", "Bankname", "Kontonummer", "Bankleitzahl", "Gruppe", "hat Zugriff", "Einschreibdatum", "Getränkeabo"}, 0); tbl_results.setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS); }

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• Calculating collision for a moving circle, without overlapping the boundaries

  - by Robert Vella

  Let's say I have circle bouncing around inside a rectangular area. At some point this circle will collide with one of the surfaces of the rectangle and reflect back. The usual way I'd do this would be to let the circle overlap that boundary and then reflect the velocity vector. The fact that the circle actually overlaps the boundary isn't usually a problem, nor really noticeable at low velocity. At high velocity it becomes quite clear that the circle is doing something it shouldn't. What I'd like to do is to programmatically take reflection into account and place the circle at it's proper position before displaying it on the screen. This means that I have to calculate the point where it hits the boundary between it's current position and it's future position -- rather than calculating it's new position and then checking if it has hit the boundary. This is a little bit more complicated than the usual circle/rectangle collision problem. I have a vague idea of how I should do it -- basically create a bounding rectangle between the current position and the new position, which brings up a slew of problems of it's own (Since the rectangle is rotated according to the direction of the circle's velocity). However, I'm thinking that this is a common problem, and that a common solution already exists. Is there a common solution to this kind of problem? Perhaps some basic theories which I should look into?

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• C++ design related question

  - by Kotti

  Hi! Here is the question's plot: suppose I have some abstract classes for objects, let's call it Object. It's definition would include 2D position and dimensions. Let it also have some virtual void Render(Backend& backend) const = 0 method used for rendering. Now I specialize my inheritance tree and add Rectangle and Ellipse class. Guess they won't have their own properties, but they will have their own virtual void Render method. Let's say I implemented these methods, so that Render for Rectangle actually draws some rectangle, and the same for ellipse. Now, I add some object called Plane, which is defined as class Plane : public Rectangle and has a private member of std::vector<Object*> plane_objects; Right after that I add a method to add some object to my plane. And here comes the question. If I design this method as void AddObject(Object& object) I would face trouble like I won't be able to call virtual functions, because I would have to do something like plane_objects.push_back(new Object(object)); and this should be push_back(new Rectangle(object)) for rectangles and new Circle(...) for circles. If I implement this method as void AddObject(Object* object), it looks good, but then somewhere else this means making call like plane.AddObject(new Rectangle(params)); and this is generally a mess because then it's not clear which part of my program should free the allocated memory. ["when destroying the plane? why? are we sure that calls to AddObject were only done as AddObject(new something).] I guess the problems caused by using the second approach could be solved using smart pointers, but I am sure there have to be something better. Any ideas?

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• Solving for the coefficent of linear equations with one known coefficent

  - by CppLearner

  clc; clear all; syms y a2 a3 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % [ 0.5 0.25 0.125 ] [ a2 ] [ y ] % [ 1 1 1 ] [ a3 ] = [ 3 ] % [ 2 4 8 ] [ 6 ] [ 2 ] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% M = [0.5 0.25 0.125; 1 1 1; 2 4 8]; t = [a2 a3 6]; r = [y 3 2]; sol = M * t' s1 = solve(sol(1), a2) % solve for a2 s2 = solve(sol(2), a3) % solve for a3 This is what I have so far. These are my output sol = conj(a2)/2 + conj(a3)/4 + 3/4 conj(a2) + conj(a3) + 6 2*conj(a2) + 4*conj(a3) + 48 s1 = - conj(a3)/2 - 3/2 - Im(a3)*i s2 = - conj(a2) - 6 - 2*Im(a2)*i sol looks like what we would have if we put them back into equation form: 0.5 * a2 + 0.25 * a3 + 0.125 * a4 a2 + a3 + a4 = 3 2*a2 + 4*a3 + 8*a4 = 2 where a4 is known == 6. My problem is, I am stuck with how to use solve to actually solve these equations to get the values of a2 and a3. s2 solve for a3 but it doesn't match what we have on paper (not quite). a2 + a3 + 6 = 3 should yield a3 = -3 - a2. because of the imaginary. Somehow I need to equate the vector solution sol to the values [y 3 2] for each row.

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• Specifying character

  - by danutenshu

  So below I have a code in C++ that is supposed to invert the arguments in a vector, but not the sequence. I have listed my problems as sidenotes in the code below. The invert function is supposed to invert each argument, and then the main function just outputs the inverted words in same order For instance, program("one two three four")=ruof eerth owt eno #include <iostream> #include <string> using namespace std; int invert(string normal) { string inverted; for (int num=normal.size()-1; num>=0; num--) { inverted.append(normal[num]); //I don't know how to get each character //I need another command for append } return **inverted**; <---- } int main(int argc, char* argv[]) { string text; for (int a=1; a<argc; a++) { text.append(invert(argv[a])); //Can't run the invert function text.append(" "); } cout << text << endl; return 0; }

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• Dynamic loading a class in java with a different package name

  - by C. Ross

  Is it possible to load a class in Java and 'fake' the package name/canonical name of a class? I tried doing this, the obvious way, but I get a "class name doesn't match" message in a ClassDefNotFoundException. The reason I'm doing this is I'm trying to load an API that was written in the default package so that I can use it directly without using reflection. The code will compile against the class in a folder structure representing the package and a package name import. ie: ./com/DefaultPackageClass.class // ... import com.DefaultPackageClass; import java.util.Vector; // ... My current code is as follows: public Class loadClass(String name) throws ClassNotFoundException { if(!CLASS_NAME.equals(name)) return super.loadClass(name); try { URL myUrl = new URL(fileUrl); URLConnection connection = myUrl.openConnection(); InputStream input = connection.getInputStream(); ByteArrayOutputStream buffer = new ByteArrayOutputStream(); int data = input.read(); while(data != -1){ buffer.write(data); data = input.read(); } input.close(); byte[] classData = buffer.toByteArray(); return defineClass(CLASS_NAME, classData, 0, classData.length); } catch (MalformedURLException e) { throw new UndeclaredThrowableException(e); } catch (IOException e) { throw new UndeclaredThrowableException(e); } }

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• C++: Reference and Pointer question (example regarding OpenGL)

  - by Jay

  I would like to load textures, and then have them be used by multiple objects. Would this work? class Sprite { GLuint* mTextures; // do I need this to also be a reference? Sprite( GLuint* textures ) // do I need this to also be a reference? { mTextures = textures; } void Draw( textureNumber ) { glBindTexture( GL_TEXTURE_2D, mTextures[ textureNumber ] ); // drawing code } }; // normally these variables would be inputed, but I did this for simplicity. const int NUMBER_OF_TEXTURES = 40; const int WHICH_TEXTURE = 10; void main() { std::vector<GLuint> the_textures; the_textures.resize( NUMBER_OF_TEXTURES ); glGenTextures( NUMBER_OF_TEXTURES, &the_textures[0] ); // texture loading code Sprite the_sprite( &the_textures[0] ); the_sprite.Draw( WHICH_TEXTURE ); } And is there a different way I should do this, even if it would work? Thanks.

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• How to create C++ istringstream from a char array with null(0) characters?

  - by Morpheus

  I have a char array which contains null characters at random locations. I tried to create an iStringStream using this array (encodedData_arr) as below, I use this iStringStream to insert binary data(imagedata of Iplimage) to a MySQL database blob field(using MySQL Connector/C++'s setBlob(istream *is) ) it only stores the characters upto the first null character. Is there a way to create an iStringStream using a char array with null characters? unsigned char *encodedData_arr = new unsigned char[data_vector_uchar->size()]; // Assign the data of vector<unsigned char> to the encodedData_arr for (int i = 0; i < vec_size; ++i) { cout<< data_vector_uchar->at(i)<< " : "<< encodedData_arr[i]<<endl; } // Here the content of the encodedData_arr is same as the data_vector_uchar // So char array is initializing fine. istream *is = new istringstream((char*)encodedData_arr, istringstream::in || istringstream::binary); prepStmt_insertImage->setBlob(1, is); // Here only part of the data is stored in the database blob field (Upto the first null character)

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• How do I overload () operator with two parameters; like (3,5)?

  - by hkBattousai

  I have a mathematical matrix class. It contains a member function which is used to access any element of the class. template >class T> class Matrix { public: // ... void SetElement(T dbElement, uint64_t unRow, uint64_t unCol); // ... }; template <class T> void Matrix<T>::SetElement(T Element, uint64_t unRow, uint64_t unCol) { try { // "TheMatrix" is define as "std::vector<T> TheMatrix" TheMatrix.at(m_unColSize * unRow + unCol) = Element; } catch(std::out_of_range & e) { // Do error handling here } } I'm using this method in my code like this: // create a matrix with 2 rows and 3 columns whose elements are double Matrix<double> matrix(2, 3); // change the value of the element at 1st row and 2nd column to 6.78 matrix.SetElement(6.78, 1, 2); This works well, but I want to use operator overloading to simplify things, like below: Matrix<double> matrix(2, 3); matrix(1, 2) = 6.78; // HOW DO I DO THIS?

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• Ping broadcast on Win XP SP3

  - by PaulH

  I'm trying to ping the broadcast address 255.255.255.255 on WinXP SP3. If I use the command line, I get host error: C:\>ping 255.255.255.255 Ping request could not find host 255.255.255.255. Please check the name and try again. If I try a C++ program using the iphlpapi, IcmpSendEcho() fails and GetLastError returns 11010 IP_REQ_TIMED_OUT. HANDLE h = ::IcmpCreateFile(); IPAddr broadcast = inet_addr( "255.255.255.255" ); BYTE payload[ 32 ] = { 0 }; IP_OPTION_INFORMATION option = { 255, 0, 0, 0, 0 }; // a buffer with room for 32 replies each containing the full payload std::vector< BYTE > replies( 32 * ( sizeof( ICMP_ECHO_REPLY ) + 32 ) ); DWORD res = ::IcmpSendEcho( h, broadcast, payload, sizeof( payload ), &option, &replies[ 0 ], replies.size(), 1000 ); ::IcmpCloseHandle( h ); I can ping the local broadcast 192.168.0.255 with no problem. What do I need to do to ping the global broadcast? Thanks, PaulH

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• Variable length argument list - How to understand we retrieved the last argument?

  - by hkBattousai

  I have a Polynomial class which holds coefficients of a given polynomial. One of its overloaded constructors is supposed to receive these coefficients via variable argument list. template <class T> Polynomial<T>::Polynomial(T FirstCoefficient, ...) { va_list ArgumentPointer; va_start(ArgumentPointer, FirstCoefficient); T NextCoefficient = FirstCoefficient; std::vector<T> Coefficients; while (true) { Coefficients.push_back(NextCoefficient); NextCoefficient = va_arg(ArgumentPointer, T); if (/* did we retrieve all the arguments */) // How do I implement this? { break; } } m_Coefficients = Coefficients; } I know that we usually pass an extra parameter which tells the recipient method the total number of parameters, or we pass a sentimental ending parameter. But in order to keep thing short and clean, I don't prefer passing an extra parameter. Is there any way of doing this without modifying the method signature in the example?

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• Looking for Go equivalent of scanf.

  - by Stephen Hsu

  I'm looking for the Go equivalent of scanf(). I tried with following code: 1 package main 2 3 import ( 4 "scanner" 5 "os" 6 "fmt" 7 ) 8 9 func main() { 10 var s scanner.Scanner 11 s.Init(os.Stdin) 12 s.Mode = scanner.ScanInts 13 tok := s.Scan() 14 for tok != scanner.EOF { 15 fmt.Printf("%d ", tok) 16 tok = s.Scan() 17 } 18 fmt.Println() 19 } I run it with input from a text with a line of integers. But it always output -3 -3 ... And how to scan a line composed of a string and some integers? Changing the mode whenever encounter a new data type? The Package documentation: Package scanner A general-purpose scanner for UTF-8 encoded text. But it seems that the scanner is not for general use. Updated code: func main() { n := scanf() fmt.Println(n) fmt.Println(len(n)) } func scanf() []int { nums := new(vector.IntVector) reader := bufio.NewReader(os.Stdin) str, err := reader.ReadString('\n') for err != os.EOF { fields := strings.Fields(str) for _, f := range fields { i, _ := strconv.Atoi(f) nums.Push(i) } str, err = reader.ReadString('\n') } r := make([]int, nums.Len()) for i := 0; i < nums.Len(); i++ { r[i] = nums.At(i) } return r }

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• Template trick to optimize out allocations

  - by anon

  I have: struct DoubleVec { std::vector<double> data; }; DoubleVec operator+(const DoubleVec& lhs, const DoubleVec& rhs) { DoubleVec ans(lhs.size()); for(int i = 0; i < lhs.size(); ++i) { ans[i] = lhs[i]] + rhs[i]; // assume lhs.size() == rhs.size() } return ans; } DoubleVec someFunc(DoubleVec a, DoubleVec b, DoubleVec c, DoubleVec d) { DoubleVec ans = a + b + c + d; } Now, in the above, the "a + b + c + d" will cause the creation of 3 temporary DoubleVec's -- is there a way to optimize this away with some type of template magic ... i.e. to optimize it down to something equivalent to: DoubleVec ans(a.size()); for(int i = 0; i < ans.size(); i++) ans[i] = a[i] + b[i] + c[i] + d[i]; You can assume all DoubleVec's have the same # of elements. The high level idea is to have do some type of templateied magic on "+", which "delays the computation" until the =, at which point it looks into itself, goes hmm ... I'm just adding thes numbers, and syntheizes a[i] + b[i] + c[i] + d[i] ... instead of all the temporaries. Thanks!

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• no instance of overloaded function getline c++

  - by Dave

  I'm a bit confused as to what i have incorrect with my script that is causing this error. I have a function which calls a fill for game settings but it doesn't like my getline. Also i should mention these are the files i have included for it: #include <fstream> #include <cctype> #include <map> #include <iostream> #include <string> #include <algorithm> #include <vector> using namespace std;' This is what i have: std::map<string, string> loadSettings(std::string file){ ifstream file(file); string line; std::map<string, string> config; while(std::getline(file, line)) { int pos = line.find('='); if(pos != string::npos) { string key = line.substr(0, pos); string value = line.substr(pos + 1); config[trim(key)] = trim(value); } } return (config); } The function is called like this from my main.cpp //load settings for game std::map<string, string> config = loadSettings("settings.txt"); //load theme for game std::map<string, string> theme = loadSettings("theme.txt"); Where did i go wrong ? Please help! The error: settings.h(61): error C2784: 'std::basic_istream<_Elem,_Traits> &std::getline(std::basic_istream<_Elem,_Traits> &&,std::basic_string<_Elem,_Traits,_Alloc> &)' : could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &&' from 'std::string'

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• Rendering maps from raw SVG data in Java

  - by Lunikon

  In an application of mine I have to display locations and great circle paths in a map which is rendered to PNG and then displayed on the web. For this I simply use a world map (NASA's Blue Marbel in fact) scaled to various "zoom levels" as base image and only display the a part of it matching the final image size and fitting all items to be displayed. Straight forward so far. Now I came across Wikipedia's awesome blank SVG maps which contain all the country codes for easy reference and I was wondering whether it was possible to use those to have more customized colors and to highliht countries etc. So I did a bit of googling and was looking for Java libraries which would enable me to load the blank SVG map to memory allows for easy reference/selection of certain paths do manipulations of coloring, stroke widths etc render to a buffered image as the background for the great-circle paths/nodes What I came across quite often was Batik, but it looks like a really heavy framework and I'm not quite sure whether it is what I'm looking for. I have recently played around with Raphaël a bit and I like the way it handles working with vector graphics in code. If the Java framework for my purpose would feature a similar interface, that would be a nice-to-have. Any recommendations what toolset would be approriate for my purposes?

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• How to Refresh / Reload a KML layer in OpenLayers. Dynamic KML Layer.

  - by Ozaki

  TLDR See my answer below on how to refresh the layer. So far I have tried action function as follows: function RefreshKMLData(layer) { layer.loaded = false; layer.setVisibility(true); layer.redraw({ force: true }); } set interval of the function: window.setInterval(RefreshKMLData, 5000, KMLLAYER); the layer itself: var KMLLAYER = new OpenLayers.Layer.Vector("MYKMLLAYER", { projection: new OpenLayers.Projection("EPSG:4326"), strategies: [new OpenLayers.Strategy.Fixed()], protocol: new OpenLayers.Protocol.HTTP({ url: MYKMLURL, format: new OpenLayers.Format.KML({ extractStyles: true, extractAttributes: true }) }) }); the url for KMLLAYER with Math random so it doesnt cache: var MYKMLURL = var currentanchorpositionurl = 'http://' + host + '/data?_salt=' + Math.random(); I would have thought that this would Refresh the layer. As by setting its loaded to false unloads it. Visibility to true reloads it and with the Math random shouldn't allow it to cache? So has anyone done this before or know how I can get this to work? TLDR See my answer below on how to refresh the layer.

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• How does does ifstream eof() work?

  - by Chan

  Hello everyone, #include <vector> #include <list> #include <map> #include <set> #include <deque> #include <stack> #include <bitset> #include <algorithm> #include <functional> #include <numeric> #include <utility> #include <sstream> #include <iostream> #include <iomanip> #include <cstdio> #include <cmath> #include <cstdlib> #include <ctime> #include <cctype> #include <fstream> using namespace std; int main() { fstream inf( "ex.txt", ios::in ); while( !inf.eof() ) { std::cout << inf.get() << "\n"; } inf.close(); inf.clear(); inf.open( "ex.txt", ios::in ); char c; while( inf >> c ) { std::cout << c << "\n"; } return 0; } I'm really confused about eof() function. Suppose my ex.txt's content is: abc It always reads an extra character and show -1. when reading using eof()? But the inf c gave the correct output which was 'abc'? Can anyone help me explain this? Best regards, Chan Nguyen

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• How to write an R function that evaluates an expression within a data-frame

  - by Prasad Chalasani

  Puzzle for the R cognoscenti: Say we have a data-frame: df <- data.frame( a = 1:5, b = 1:5 ) I know we can do things like with(df, a) to get a vector of results. But how do I write a function that takes an expression (such as a or a > 3) and does the same thing inside. I.e. I want to write a function fn that takes a data-frame and an expression as arguments and returns the result of evaluating the expression "within" the data-frame as an environment. Never mind that this sounds contrived (I could just use with as above), but this is just a simplified version of a more complex function I am writing. I tried several variants ( using eval, with, envir, substitute, local, etc) but none of them work. For example if I define fn like so: fn <- function(dat, expr) { eval(expr, envir = dat) } I get this error: > fn( df, a ) Error in eval(expr, envir = dat) : object 'a' not found Clearly I am missing something subtle about environments and evaluation. Is there a way to define such a function?

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• Solving quadratic programming using R

  - by user702846

  I would like to solve the following quadratic programming equation using ipop function from kernlab : min 0.5*x'*H*x + f'*x subject to: A*x <= b Aeq*x = beq LB <= x <= UB where in our example H 3x3 matrix, f is 3x1, A is 2x3, b is 2x1, LB and UB are both 3x1. edit 1 My R code is : library(kernlab) H <- rbind(c(1,0,0),c(0,1,0),c(0,0,1)) f = rbind(0,0,0) A = rbind(c(1,1,1), c(-1,-1,-1)) b = rbind(4.26, -1.73) LB = rbind(0,0,0) UB = rbind(100,100,100) > ipop(f,H,A,b,LB,UB,0) Error in crossprod(r, q) : non-conformable arguments I know from matlab that is something like this : H = eye(3); f = [0,0,0]; nsamples=3; eps = (sqrt(nsamples)-1)/sqrt(nsamples); A=ones(1,nsamples); A(2,:)=-ones(1,nsamples); b=[nsamples*(eps+1); nsamples*(eps-1)]; Aeq = []; beq = []; LB = zeros(nsamples,1); UB = ones(nsamples,1).*1000; [beta,FVAL,EXITFLAG] = quadprog(H,f,A,b,Aeq,beq,LB,UB); and the answer is a vector of 3x1 equals to [0.57,0.57,0.57]; However when I try it on R, using ipop function from kernlab library ipop(f,H,A,b,LB,UB,0)) and I am facing Error in crossprod(r, q) : non-conformable arguments I appreciate any comment

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