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  • Binning a numeric variable in R

    - by McPeterson
    I have a vector X that contains positive numbers that I want to bin/discretize. For this vector, I want the numbers [0, 10) to show up just as they exist in the vector, but numbers [10,∞) to be 10+. I'm using: x <- c(0,1,3,4,2,4,2,5,43,432,34,2,34,2,342,3,4,2) binned.x <- as.factor(ifelse(x > 10,"10+",x)) but this feels klugey to me. Does anyone know a better solution or a different approach? mcpeterson

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  • Sorting MySQL results within a resultset

    - by InnateDev
    I have a resultset of lets say 10 results. 3 of them have a type 'Pears', and the next 3 have a type 'Apples' and the next three have a type of 'Bananas'. The last record has a type of 'Squeezing Equipment' - unrelated to the fruits. How do I return this set of results (for pagination too) in a GROUPED order that I specify WITHOUT using any inherent sort factor like ALPHABETA or ID etc? I have the all types at my disposal before running the code so they can be specified. i.e. ID | Bananas ID | Bananas ID | Bananas ID | Apples ID | Apples ID | Apples ID | Pears ID | Pears ID | Pears ID | Squeezing Equipment

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  • whats the diference between train, validation and test set, in neural networks?

    - by Daniel
    Im using this library http://pastebin.com/raw.php?i=aMtVv4RZ to implement a learning agent. I have generated the train cases, but i dont know for sure what are the validation and test sets, the teacher says: 70% should be train cases, 10% will be test cases and the rest 20% should be validation cases. Thanks. edit i have this code, for training.. but i have no ideia when to stop training.. def train(self, train, validation, N=0.3, M=0.1): # N: learning rate # M: momentum factor accuracy = list() while(True): error = 0.0 for p in train: input, target = p self.update(input) error = error + self.backPropagate(target, N, M) print "validation" total = 0 for p in validation: input, target = p output = self.update(input) total += sum([abs(target - output) for target, output in zip(target, output)]) #calculates sum of absolute diference between target and output accuracy.append(total) print min(accuracy) print sum(accuracy[-5:])/5 #if i % 100 == 0: print 'error %-14f' % error if ? < ?: break

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  • jquery $(window).width() and $(window).height() return different values when viewport has not been r

    - by Manca Weeks
    I am writing a site using jquery that repeatedly repeatedly calls $(window).width() and $(window).height() to position and size elements based on the viewport size... In troubleshooting I discovered that I am getting slightly different viewport size reports in repeated calls to the above jquery functions when the viewport is not resized... Wondering if there is any special case anyone knows of when this happens, or if this is just the way it is. The difference in sizes reported are 20px or less, it appears. It happens in Safari 4.0.4, Firefox 3.6.2 and Chrome 5.0.342.7 beta on Mac OS X 10.6.2... I didn't test other browsers yet because it doesn't appear to be specific to the browser. I was also unable to figure out what the difference depends upon - if it isn't the viewport size, could there be another factor that makes the results differ? Any insight would be appreciated... Thanks MAnca

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  • SQL to return dates that fall in period and range

    - by Nate
    Hey stackers, I’ve been grinding my head on this for a while… My goal is to return all dates that fall between a start and end date and have a certain period as a factor, from the start date. (hard to explain) For example… Start Date: Nov 20, 1987; End Date: Jan 01, 1988; Period: 10 days; I want these dates: Nov 20, 1987; Nov 30, 1987; Dec 10, 1987; Dec 20, 1987; Dec 30, 1987; I already have a date table with all dates from 1900 to 2099. The period could be by days, months or years. Any ideas? Let me know if you need more info.

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  • Animation with Initial Velocity

    - by abustin
    I've been trying to solve this problem for a number of days now but I must be missing something. Known Variables: vi = Initial Velocity t = Animation Duration d = Distance The function I'm trying to create: D(t) = the current distance for a given time Using this information I want to be able to create a smooth animation curve with varying velocity (ease-in/ease-out). The animation must be able ease-in from an initial velocity. The animation must be exactly t seconds and must be travel exactly d units. The curve should lean towards the average velocity with acceleration occurring at the beginning and the end portions of the curve. I'm open to extra configuration variables. The best I've been able to come up with is something that doesn't factor in the initial velocity. I'm hoping someone smarter can help me out. ;) Thank you! p.s. I'm working with an ECMAScript variant

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  • Setting up a web developer lab for learning purposes

    - by Saleh Al-Abbas
    I'm not a developer by profession. Therefore, I'm not exposed to real world technical problems that face professional developers. I read/heard about web farms, integration between different systems, load balancing ... etc. Therefore, I was wondering if there are ways for the individual developer to create an environment that simulates real world situations with minimal number of machines like: web farms & caching simulating many users accessing your website (Pressure tests?) Performance load balancing anything you think I should consider. By the way, I have a server machine and 1 PC. and I don't mind investing in tools and software. PS. I'm using Microsoft technologies for development but I hope this is not a limiting factor. Thanks

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  • Restart program from a certain line with an if statement?

    - by user1744093
    could anyone help me restart my program from line 46 if the user enters 1 (just after the comment where it states that the next code is going to ask the user for 2 inputs) and if the user enters -1 end it. I cannot think how to do it. I'm new to C# any help you could give would be great! class Program { static void Main(string[] args) { //Displays data in correct Format List<float> inputList = new List<float>(); TextReader tr = new StreamReader("c:/users/tom/documents/visual studio 2010/Projects/DistanceCalculator3/DistanceCalculator3/TextFile1.txt"); String input = Convert.ToString(tr.ReadToEnd()); String[] items = input.Split(','); Console.WriteLine("Point Latitude Longtitude Elevation"); for (int i = 0; i < items.Length; i++) { if (i % 3 == 0) { Console.Write((i / 3) + "\t\t"); } Console.Write(items[i]); Console.Write("\t\t"); if (((i - 2) % 3) == 0) { Console.WriteLine(); } } Console.WriteLine(); Console.WriteLine(); // Ask for two inputs from the user which is then converted into 6 floats and transfered in class Coordinates Console.WriteLine("Please enter the two points that you wish to know the distance between:"); string point = Console.ReadLine(); string[] pointInput = point.Split(' '); int pointNumber = Convert.ToInt16(pointInput[0]); int pointNumber2 = Convert.ToInt16(pointInput[1]); Coordinates distance = new Coordinates(); distance.latitude = (Convert.ToDouble(items[pointNumber * 3])); distance.longtitude = (Convert.ToDouble(items[(pointNumber * 3) + 1])); distance.elevation = (Convert.ToDouble(items[(pointNumber * 3) + 2])); distance.latitude2 = (Convert.ToDouble(items[pointNumber2 * 3])); distance.longtitude2 = (Convert.ToDouble(items[(pointNumber2 * 3) + 1])); distance.elevation2 = (Convert.ToDouble(items[(pointNumber2 * 3) + 2])); //Calculate the distance between two points const double PIx = 3.141592653589793; const double RADIO = 6371; double dlat = ((distance.latitude2) * (PIx / 180)) - ((distance.latitude) * (PIx / 180)); double dlon = ((distance.longtitude2) * (PIx / 180)) - ((distance.longtitude) * (PIx / 180)); double a = (Math.Sin(dlat / 2) * Math.Sin(dlat / 2)) + Math.Cos((distance.latitude) * (PIx / 180)) * Math.Cos((distance.latitude2) * (PIx / 180)) * (Math.Sin(dlon / 2) * Math.Sin(dlon / 2)); double angle = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a)); double ultimateDistance = (angle * RADIO); Console.WriteLine("The distance between your two points is..."); Console.WriteLine(ultimateDistance); //Repeat the program if the user enters 1, end the program if the user enters -1 Console.WriteLine("If you wish to calculate another distance type 1 and return, if you wish to end the program, type -1."); Console.ReadLine(); if (Convert.ToInt16(Console.ReadLine()) == 1); { //here is where I need it to repeat }

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  • Creating a new coloumn for date info with specific date format

    - by Ayan
    Dear All I am working with a file which has few years data and I am trying to create an aditional coloumn that reads the year and month info from the date coloumn (e.g. 01/01/1997 12:00) and create a new coloumn with month and year together(e.g. Jan-97). I am not sure how to proceed with this but what I am trying to code is the coloumn with name "new_date" in the following picture: my sample data = > dput(df) structure(list(date = structure(c(1L, 4L, 7L, 2L, 5L, 8L, 3L, 6L, 9L), .Label = c("01/01/1997 12:00", "01/01/1998 15:00", "01/01/1999 18:00", "01/02/1997 13:00", "01/02/1998 16:00", "01/02/1999 19:00", "01/03/1997 14:00", "01/03/1998 17:00", "01/03/1999 19:00"), class = "factor"), value = c(29L, 31L, 42L, 42L, 52L, 61L, 57L, 55L, 56L)), .Names = c("date", "value"), row.names = c(NA, -9L), class = "data.frame") I would really appreciate if you could advise me about how should I proceed with this, Many thanks, Ayan

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  • Tabbed javascript widget for a Rails app

    - by neilc
    A user registers on our Rails app and they're given javascript to embed a widget in their website. The widget has a tabbed interface, like the JQuery tabs http://stilbuero.de/jquery/tabs_3/. iFrames have been tested, but the widget form factor and cross-domain policy negates the use of iframes. The widget is very dynamic and will often update the DOM with new content - and because of cross-domain policy, it looks as though JSONP is necessary. I understand that 'widget.js.erb' needs to create the widget layout, reference a stylesheet, render the tabs, etc - but once a tab is clicked, how does the widget request the content from the Rails app and render it in the DOM?

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  • Finding the Formula for a Curve

    - by Mystagogue
    Is there a program that will take "response curve" values from me, and provide a formula that approximates the response curve? It would be cool if such a program would take a numeric "percent correct" (perhaps with a standard deviation) so that it returns simplified formulas when laxity is permissable, and more precise (viz. complex) formulas when the curve needs to be approximated closely. My interest is to play with the response curve values and "laxity" factor, until such a tool spits out a curve-fit formula simple enough that I know it will be high performance during machine computations.

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  • How to save objects using Multi-Threading in Core Data?

    - by Konstantin
    I'm getting some data from the web service and saving it in the core data. This workflow looks like this: get xml feed go over every item in that feed, create a new ManagedObject for every feed item download some big binary data for every item and save it into ManagedObject call [managedObjectContext save:] Now, the problem is of course the performance - everything runs on the main thread. I'd like to re-factor as much as possible to another thread, but I'm not sure where I should start. Is it OK to put everything (1-4) to the separate thread?

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  • General zoom algorithm for drawing program

    - by Steven Sproat
    My GUI toolkit, wxPython provides some methods for implementing a user zoom factor, however the quality isn't too good. I'm looking for ideas on how to create a zooming feature, which I know is complicated. I have a bitmap representing my canvas which is drawn to. This is displayed inside a scrolled window. Problems I forsee: - performance when zoomed in and panning around the canvas - difficulties with "real" coordinates and zoomed in coordinates - image quality not degrading with the zoom Using wxPython's SetUserScale() on its device contexts presents image quality like this - this is with a 1px line, at 30% zoomed in. I'm just wondering the general steps I'll need to take and the challenges I'll encounter. Thanks for any suggestions

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  • Parallel Programming. Boost's MPI, OpenMP, TBB, or something else?

    - by unknownthreat
    Hello, I am totally a novice in parallel programming, but I do know how to program C++. Now, I am looking around for parallel programming library. I just want to give it a try, just for fun, and right now, I found 3 APIs, but I am not sure which one should I stick with. Right now, I see Boost's MPI, OpenMP and TBB. For anyone who have experienced with any of these 3 API (or any other parallelism API), could you please tell me the difference between these? Are there any factor to consider, like AMD or Intel architecture?

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  • Whats the difference between Paxos and W+R>=N in Cassandra?

    - by user1128016
    Dynamo-like databases (e.g. Cassandra) provide ability to enforce consistency by means of quorum, i.e. a number of synchronously written replicas (W) and a number of replicas to read (R) should be chosen in such a way that W+RN where N is a replication factor. On the other hand, PAXOS-based systems like Zookeeper are also used as a consistent fault-tolerant storage. What is the difference between these two approaches? Does PAXOS provide guarantees that are not provided by W+RN schema?

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  • Cassandra performance slow down with counter column

    - by tubcvt
    I have a cluster (4 node ) and a node have 16 core and 24 gb ram: 192.168.23.114 datacenter1 rack1 Up Normal 44.48 GB 25.00% 192.168.23.115 datacenter1 rack1 Up Normal 44.51 GB 25.00% 192.168.23.116 datacenter1 rack1 Up Normal 44.51 GB 25.00% 192.168.23.117 datacenter1 rack1 Up Normal 44.51 GB 25.00% We use about 10 column family (counter column) to make some system statistic report. Problem on here is that When i set replication_factor of this keyspace from 1 to 2 (contain 10 counter column family ), all cpu of node increase from 10% ( when use replication factor=1) to --- 90%. :( :( who can help me work around that :( . why counter column consume too much cpu time :(. thanks all

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  • What is the best Java numerical method package?

    - by Bob Cross
    I am looking for a Java-based numerical method package that provides functionality including: Solving systems of equations using different numerical analysis algorithms. Matrix methods (e.g., inversion). Spline approximations. Probability distributions and statistical methods. In this case, "best" is defined as a package with a mature and usable API, solid performance and numerical accuracy. Edit: derick van brought up a good point in that cost is a factor. I am heavily biased in favor of free packages but others may have a different emphasis.

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  • Compiler error: Variable or field declared void [closed]

    - by ?? ?
    i get some error when i try to run this, could someone please tell me the mistakes, thank you! [error: C:\Users\Ethan\Desktop\Untitled1.cpp In function `int main()': 25 C:\Users\Ethan\Desktop\Untitled1.cpp variable or field `findfactors' declared void 25 C:\Users\Ethan\Desktop\Untitled1.cpp initializer expression list treated as compound expression] #include<iostream> #include<cmath> using namespace std; void prompt(int&, int&, int&); int gcd(int , int , int );//3 input, 3 output void findfactors(int , int , int, int, int&, int&);//3 input, 2 output void display(int, int, int, int, int);//5 inputs int main() { int a, b, c; //The coefficients of the quadratic polynomial int ag, bg, cg;//value of a, b, c after factor out gcd int f1, f2; //The two factors of a*c which add to be b int g; //The gcd of a, b, c prompt(a, b, c);//Call the prompt function g=gcd(a, b, c);//Calculation of g void findfactors(a, b, c, f1, f2);//Call findFactors on factored polynomial display(g, f1, f2, a, c);//Call display function to display the factored polynomial system("PAUSE"); return 0; } void prompt(int& num1, int& num2, int& num3) //gets 3 ints from the user { cout << "This program factors polynomials of the form ax^2+bx+c."<<endl; while(num1==0) { cout << "Enter a value for a: "; cin >> num1; if(num1==0) { cout<< "a must be non-zero."<<endl; } } while(num2==0 && num3==0) { cout << "Enter a value for b: "; cin >> num2; cout << "Enter a value for c: "; cin >> num3; if(num2==0 && num3==0) { cout<< "b and c cannot both be 0."<<endl; } } } int gcd(int num1, int num2, int num3) { int k=2, gcd=1; while (k<=num1 && k<=num2 && k<=num3) { if (num1%k==0 && num2%k==0 && num3%k==0) gcd=k; k++; } return gcd; } void findFactors(int Ag, int Bg, int Cg,int& F1, int& F2) { int y=Ag*Cg; int z=sqrt(abs(y)); for(int i=-z; i<=z; i++) //from -sqrt(|y|) to sqrt(|y|) { if(i==0)i++; //skips 0 if(y%i==0) //if i is a factor of y { if(i+y/i==Bg) //if i and its partner add to be b F1=i, F2=y/i; else F1=0, F2=0; } } } void display(int G, int factor1, int factor2, int A, int C) { int k=2, gcd1=1; while (k<=A && k<=factor1) { if (A%k==0 && factor1%k==0) gcd1=k; k++; } int t=2, gcd2=1; while (t<=factor2 && t<=C) { if (C%t==0 && factor2%t==0) gcd2=t; t++; } cout<<showpos<<G<<"*("<<gcd1<<"x"<<gcd2<<")("<<A/gcd1<<"x"<<C/gcd2<<")"<<endl; }

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  • What are the reasons to use SQL Server instead of MySQL with a complex .Net project?

    - by cdeszaq
    We currently have a 10 year old nasty, spaghetti-code-style SQL Server database that we are soon looking to pretty much re-write from scratch as part of a re-write to a large web application. (The existing application will serve as the functional requirements for the next incarnation of the app) The new version will be developed in .Net, so a large portion of the application stack will be based on Microsoft technologies (Visual Studio will be used IIS will be the application server). One of the developers on the project has raised the possibility of switching to MySQL instead of SQL Server in order to save on cost for both the licence of the DB server, as well as the tools to design and manipulate the DB (such as the wonderfully free MySQL Workbench). What are the various pros and cons of using SQL Server vs. MySQL as the database for a complex .Net project? Price is one factor we have identified, both in terms of the DB server licence as well as tools to manipulate the DB, but what other factors come into play?

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  • How many instructions to access pointer in C?

    - by Derek
    Hi All, I am trying to figure out how many clock cycles or total instructions it takes to access a pointer in C. I dont think I know how to figure out for example, p-x = d-a + f-b i would assume two loads per pointer, just guessing that there would be a load for the pointer, and a load for the value. So in this operations, the pointer resolution would be a much larger factor than the actual addition, as far as trying to speed this code up, right? This may depend on the compiler and architecture implemented, but am I on the right track? I have seen some code where each value used in say, 3 additions, came from a f2->sum = p1->p2->p3->x + p1->p2->p3->a + p1->p2->p3->m type of structure, and I am trying to define how bad this is

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  • Code runs 6 times slower with 2 threads than with 1

    - by Edward Bird
    So I have written some code to experiment with threads and do some testing. The code should create some numbers and then find the mean of those numbers. I think it is just easier to show you what I have so far. I was expecting with two threads that the code would run about 2 times as fast. Measuring it with a stopwatch I think it runs about 6 times slower! void findmean(std::vector<double>*, std::size_t, std::size_t, double*); int main(int argn, char** argv) { // Program entry point std::cout << "Generating data..." << std::endl; // Create a vector containing many variables std::vector<double> data; for(uint32_t i = 1; i <= 1024 * 1024 * 128; i ++) data.push_back(i); // Calculate mean using 1 core double mean = 0; std::cout << "Calculating mean, 1 Thread..." << std::endl; findmean(&data, 0, data.size(), &mean); mean /= (double)data.size(); // Print result std::cout << " Mean=" << mean << std::endl; // Repeat, using two threads std::vector<std::thread> thread; std::vector<double> result; result.push_back(0.0); result.push_back(0.0); std::cout << "Calculating mean, 2 Threads..." << std::endl; // Run threads uint32_t halfsize = data.size() / 2; uint32_t A = 0; uint32_t B, C, D; // Split the data into two blocks if(data.size() % 2 == 0) { B = C = D = halfsize; } else if(data.size() % 2 == 1) { B = C = halfsize; D = hsz + 1; } // Run with two threads thread.push_back(std::thread(findmean, &data, A, B, &(result[0]))); thread.push_back(std::thread(findmean, &data, C, D , &(result[1]))); // Join threads thread[0].join(); thread[1].join(); // Calculate result mean = result[0] + result[1]; mean /= (double)data.size(); // Print result std::cout << " Mean=" << mean << std::endl; // Return return EXIT_SUCCESS; } void findmean(std::vector<double>* datavec, std::size_t start, std::size_t length, double* result) { for(uint32_t i = 0; i < length; i ++) { *result += (*datavec).at(start + i); } } I don't think this code is exactly wonderful, if you could suggest ways of improving it then I would be grateful for that also.

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  • Overcoming C limitations for large projects

    - by Francisco Garcia
    One aspect where C shows its age is the encapsulation of code. Many modern languages has classes, namespaces, packages... a much more convenient to organize code than just a simple "include". Since C is still the main language for many huge projects. How do you to overcome its limitations? I suppose that one main factor should be lots of discipline. I would like to know what you do to handle large quantity of C code, which authors or books you can recommend.

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  • Multi-Core Programming. Boost's MPI, OpenMP, TBB, or something else?

    - by unknownthreat
    Hello, I am totally a novice in Multi-Core Programming, but I do know how to program C++. Now, I am looking around for Multi-Core Programming library. I just want to give it a try, just for fun, and right now, I found 3 APIs, but I am not sure which one should I stick with. Right now, I see Boost's MPI, OpenMP and TBB. For anyone who have experienced with any of these 3 API (or any other API), could you please tell me the difference between these? Are there any factor to consider, like AMD or Intel architecture?

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  • more ruby way of gsub from array

    - by aharon
    My goal is to let there be x so that x("? world. what ? you say...", ['hello', 'do']) returns "hello world. what do you say...". I have something that works, but seems far from the "Ruby way": def x(str, arr, rep='?') i = 0 query.gsub(rep) { i+=1; arr[i-1] } end Is there a more idiomatic way of doing this? (Let me note that speed is the most important factor, of course.)

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  • Pass Types as arguments to a function in Haskell?

    - by Charles Peng
    The following two functions are extremely similar. They read from a [String] n elements, either [Int] or [Float]. How can I factor the common code out? I don't know of any mechanism in Haskell that supports passing types as arguments. readInts n stream = foldl next ([], stream) [1..n] where next (lst, x:xs) _ = (lst ++ [v], xs) where v = read x :: Int readFloats n stream = foldl next ([], stream) [1..n] where next (lst, x:xs) _ = (lst ++ [v], xs) where v = read x :: Float I am at a beginner level of Haskell, so any comments on my code are welcome.

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