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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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  • measuring uncertainty in matlabs svmclassify

    - by Mark
    I'm doing contextual object recognition and I need a prior for my observations. e.g. this space was labeled "dog", what's the probability that it was labeled correctly? Do you know if matlabs svmclassify has an argument to return this level of certainty with it's classification? If not, matlabs svm has the following structures in it: SVM = SupportVectors: [11x124 single] Alpha: [11x1 double] Bias: 0.0915 KernelFunction: @linear_kernel KernelFunctionArgs: {} GroupNames: {11x1 cell} SupportVectorIndices: [11x1 double] ScaleData: [1x1 struct] FigureHandles: [] Can you think of any ways to compute a good measure of uncertainty from these? (Which support vector to use?) Papers/articles explaining uncertainty in SVMs welcome. More in depth explanations of matlabs SVM are also welcome. If you can't do it this way, can you think of any other libraries with SVMs that have this measure of uncertainty?

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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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  • C++ refactor common code with one different statement

    - by user231536
    I have two methods f(vector<int>& x, ....) and g(DBConn& x, ....) where the (....) parameters are all identical. The code inside the two methods are completely identical except for one statement where we do different actions based on the type of x: in f(): we do x.push_back(i) in g(): we do x.DeleteRow(i) What is the simplest way to extract the common code into one method and yet have the two different statements? I am thinking of having a templated functor that overloads operator () (int a) but that seems overkill.

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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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  • Filtering spectrum using FIR filters

    - by Alex Hoppus
    If i have signal values x[T] and filter coefficients b[i], i can perform filtering using convolution. Suppose i have spectrum of x (after FFT) and i need to perform filtering using filters coefficients, how can i perform this? I heard that in frequency domain it will be multiplying, rather than convolution (time domain). But i can't find an equation to use it. I have 614000 values in y = fft(x[T]) vector and 119 filter coefficients (generated using fdatool), i can't multiply them directly ... Thanks.

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  • Calculating the null space of a matrix

    - by Ainsworth
    I'm attempting to solve a set of equations of the form Ax = 0. A is known 6x6 matrix and I've written the below code using SVD to get the vector x which works to a certain extent. The answer is approximately correct but not good enough to be useful to me, how can I improve the precision of the calculation? Lowering eps below 1.e-4 causes the function to fail. from numpy.linalg import * from numpy import * A = matrix([[0.624010149127497 ,0.020915658603923 ,0.838082638087629 ,62.0778180312547 ,-0.336 ,0], [0.669649399820597 ,0.344105317421833 ,0.0543868015800246 ,49.0194290212841 ,-0.267 ,0], [0.473153758252885 ,0.366893577716959 ,0.924972565581684 ,186.071352614705 ,-1 ,0], [0.0759305208803158 ,0.356365401030535 ,0.126682113674883 ,175.292109352674 ,0 ,-5.201], [0.91160934274653 ,0.32447818779582 ,0.741382053883291 ,0.11536775372698 ,0 ,-0.034], [0.480860406786873 ,0.903499596111067 ,0.542581424762866 ,32.782593418975 ,0 ,-1]]) def null(A, eps=1e-3): u,s,vh = svd(A,full_matrices=1,compute_uv=1) null_space = compress(s <= eps, vh, axis=0) return null_space.T NS = null(A) print "Null space equals ",NS,"\n" print dot(A,NS)

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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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  • Pass data in np.dnarray to Highcharts

    - by F.N.B
    I'm working with python 2.7, jinja2, flask and Highcharts. I create two numpy array (x1 and x2, type = numpy.dnarray) and I pass to Highcharts. My problems is, Highcharts don't recognize the commas in the vector. This is my jinja2 code: <script> $(function () { $('#container').highcharts({ series: [{ name: 'Tokyo', data: {{ x1 }} }, { name: 'London', data: {{ x2 }} }] }); }); And this is the error that I look with network chrome dev tools: series: [{ name: 'Tokyo', data: [1 4 5 2 3] }, { name: 'London', data: [3 6 7 4 1] }] I need change the numpy array to python list to pass to Highcharts or there is a better way to do?? Thanks

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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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  • The C vs. C++ way

    - by amc
    Hi, So I have to write a program that will iterate through an image and record the pixel locations corresponding to each color pixel that appears in it. For example, given http://www.socuteurl.com/fishywishykissy I need to find the coordinates of all yellow, purple, dark pink, etc pixels. In C++ I would use a hash table to do this. I would iterate through the image, check each pixel's value, look up that value and either add to a vector of pixel coordinates if it were found or add a new entry to the table if the value were not already there. The problem is that I may need to write this program in pure C instead of C++. How would I go about doing this in C? I feel like implementing a hash table would be pretty obnoxious and error-prone: should I avoid doing that? I'm pretty inexperienced with C and have a fair amount of C++ experience, if that matters. Thanks.

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  • custom Filter Android won't show me the results

    - by TiGer
    Hi, I have been implementing a class which class extends ArrayAdapter and implements Filterable. The filtering part (in the performFiltering method()) seems to go ok, it fills the FilterResults object just as expected. But then I think I'm not doing it right on how to publish the results, atm I have : protected void publishResults(CharSequence prefix, FilterResults results) { // NOTE: this function is *always* called from the UI thread. subItems = (Vector)results.values; notifyDataSetChanged(); } But this simply won't "populate" my List with the received data. So now my question is how do I populate my List with the received results ? Do I have to do that programmatically ?

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  • Java ME Application running fine in Emulator but crashing when deployed to N70. Any way to identify

    - by sana
    I have developed a Java ME application for CLDC platform. It works fine when executed in an emulator. But when i deploy it to my N70 phone the application doesn't start at all in the phone. In my application there are some 14 classes and am creating an instance of each and putting them in the vector on application start. The classes just have one variable and 2 methods. Can this creating of lot of instances be the reason for its crashing? Is there any way I can find out the reason why the application is not able to start in the phone?

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  • R: Cut and labels/breaks length conflict

    - by AkselO
    I am working with the cut function to prep data for a barplot histogram but keep running into a seeming inconsistency between my labels and breaks: Error in cut.default(sample(1:1e+05, 500, T), breaks = sq, labels = sprintf("$%.0f", : labels/breaks length conflict Here is an example. I pretend that it is income data, using a sequence of 0 to $100,000 in bins of $10,000. I use the same variable to generate both breaks and labels, with minor formating on the label side. I thought they might for some reason have different lengths when comparing to a character vector, but they appear to have the same length, still. > sq<-seq(0,100000,10000) > cut(sample(1:100000, 500, T),breaks=sq,labels=sprintf("$%.0f",sq)) > length(sprintf("$%.0f",sq)) [1] [11] > length(sq) [1] [11]

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  • Twin edges - Half edge data structure

    - by Pradeep Kumar
    I have implemented a Half-edge data structure for loading 3d objects. I find that the part of assigning twin/pair edges takes the longest computation time (especially for objects which have hundreds of thousands half edges). The reason is that I use nested loops to accomplish this. Is there a simpler and efficient way of doing this? Below is the code which I've written. HE is the half-edge data structure. hearr is a vector containing all the half edges. vert is the starting vertex and end is the ending vertex. Thanks!! HE *e1,*e2; for(size_t i=0;i<hearr.size();i++){ e1=hearr[i]; for(size_t j=1;j<hearr.size();j++){ e2=hearr[j]; if((e1->vert==e2->end)&&(e2->vert==e1->end)){ e1->twin=e2; e2->twin=e1; } } }

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  • What is a good standard for code width?

    - by BillyONeal
    Hello everyone :) I've heard in several places that it's bad to have code that is too wide onscreen. For example: for (std::vector<EnumServiceInformation>::const_iterator currentService = services.begin(); currentService != services.end(); currentService++) However, I've heard many arguments for 80 character wide limits. I'm assuming this 80 character limit comes from the traditional command prompt, which is typically 80 characters wide. However -- most of us are working on something much better than a typical command prompt, and I feel that using an 80 character limit encourages use of variable names that are far too short and do not describe what the variable is used for. What is a reasonable limit for a new project with no existing coding width standard?

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  • Create a table of Quantiles in R for multiple Subsets of Data

    - by user1489719
    I'm trying to create append a table of quantiles in R for multiple subsets of data. Right now, I have a vector of ids (p_ids) in table DATA, which are not consecutive. For each value in p_ids, I am looking to list the quantile. So far, I've tried variations of: i <- 1 n <- 1 for (i in p_ids) { while(n <= nrow(data)) { quantiles[n] <- quantile(subset(alldata$variableA, alldata$variableB == i),probs = c(0,1,2,3)/3) n <- n + 1 } } I know my issue lies somewhere in the index, but I can't seem to get where the index should go. Suggestions?

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  • Javascript function returning number with two decimals...?

    - by muzzledBYbrass
    I have a function to return points along a line and my return comes back with two decimal points...? For example, a return of my variable px will be something like -88.4029.032940598. vx is the x vector and mult is the distance of the line plus distance to calculate the point. Here is the operation that is returning these values: var mult = parseFloat(mag + theUnit); var px = coord_one.x_point + (vx * mult); console.log(px); Never have seen this before- I appreciate any and all help!

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  • CSV parser in C++

    - by User1
    All I need is a good CSV file parser for C++. At this point it can really just be a comma-delimited parser (ie don't worry about escaping new lines and commas). The main need is a line-by-line parser that will return a vector for the next line each time the method is called. I found this article which looks quite promising: http://www.boost.org/doc/libs/1_35_0/libs/spirit/example/fundamental/list_parser.cpp I've never used Boost's Spirit, but am willing to try it. Is it overkill/bloated or is it fast and efficient? Does anyone have faster algorithms using STL or anything else? Thanks!

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  • Collection type generated by for with yield

    - by Jesper
    When I evaluate a for in Scala, I get an immutable IndexedSeq (a collection with array-like performance characteristics, such as efficient random access): scala> val s = for (i <- 0 to 9) yield math.random + i s: scala.collection.immutable.IndexedSeq[Double] = Vector(0.6127056766832756, 1.7137598183155291, ... Does a for with a yield always return an IndexedSeq, or can it also return some other type of collection class (a LinearSeq, for example)? If it can also return something else, then what determines the return type, and how can I influence it? I'm using Scala 2.8.0.RC3.

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  • allocator with no template

    - by Merni
    Every stl container take an allocator as a second object, template < class T, class Allocator = allocator<T> > class vector; If you write your own class It is possible to use your own allocator. But is it possible to write your own allocator without using templates? For example, writing this function is not easy if you are not allowed to use templates pointer allocate(size_type n, const_pointer = 0) { void* p = std::malloc(n * sizeof(T)); if (!p) throw std::bad_alloc(); return static_cast<pointer>(p); } Because how could you know the size of T?

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  • Unexpected result from reduce function

    - by StackedCrooked
    I would like to get the smallest element from a vector. For this I use combine the reduce and min functions. However, when providing my own implementation of min I get unexpected results: user=> (reduce (fn [x y] (< x y) x y) [1 2 3 2 1 0 1 2]) 2 user=> (reduce min [1 2 3 2 1 0 1 2 3]) 0 The reduce with standard min returns 0 as expected. However, when I provide my own implementation it returns 2. What am I doing wrong?

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  • HELP!! Implementing a search to match the specified author and displaying a book by the specified publisher

    - by Brian
    Hey guys! So i'm having problems with my assignment. I successfully got it to run multiple last names by the author, but now, I need to find all books by author, which means searching the collection for all books that match the specified author and I also need to find all books by publisher, which displays a list of books by the specified publisher. How would I implement this? Would I use string or vector? Any help will be much appreciated!

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  • Designing entire webpages as SVG files

    - by user1311390
    Disclaimer I realize that given the absurdity of the title, this sounds like a troll. However, it's a genuine question. My background involves OpenGL / x86 assembly. I've recently started learning web programming. I really like SVG + CSS, and was wondering -- why do people not design entire webpages in SVG? Context SVG provides beautiful primitive: quadratic + cubic bezier curves; lines + filling -- all as vector graphics SVG provides text SVG provides affine transformations Questions Are there examples of people designing entire websites as a giant SVG file? If not, what the limitations? Are there performance hits when using SVG primitives as opposed to divs/tables?

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  • Evaluation of (de)reference operators

    - by Micha
    I have an (uncommented...) source file which I'm trying to understand. static const Map *gCurMap; static std::vector<Map> mapVec; then auto e = mapVec.end(); auto i = mapVec.begin(); while(i!=e) { // ... const Map *map = gCurMap = &(*(i++)); // ... } I don't understand what &(*(i++)) does. It does not compile when just using i++, but to me it looks the same, because I'm "incrementing" i, then I'm requesting the value at the given address and then I'm requesting the address of this value?!

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