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  • struct constructor + function parameter

    - by Oops
    Hi, I am a C++ beginner. I have the following code, the reult is not what I expect. The question is why, resp. what is wrong. For sure, the most of you see it at the first glance. struct Complex { float imag; float real; Complex( float i, float r) { imag = i; real = r; } Complex( float r) { Complex(0, r); } std::string str() { std::ostringstream s; s << "imag: " << imag << " | real: " << real << std::endl; return s.str(); } }; class Complexes { std::vector<Complex> * _complexes; public: Complexes(){ _complexes = new std::vector<Complex>; } void Add( Complex elem ) { _complexes->push_back( elem ); } std::string str( int index ) { std::ostringstream oss; Complex c = _complexes->at(index); oss << c.str(); return oss.str(); } }; int main(){ Complexes * cs = new Complexes(); //cs->Add(123.4f); cs->Add(Complex(123.4f)); std::cout << cs->str(0); return 0; } for now I am interested in the basics of c++ not in the complexnumber theory ;-) it would be nice if the "Add" function does also accept one real (without an extra overloading) instead of only a Complex-object is this possible? many thanks in advance Oops

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  • DotNetOpenAuth getting return_To url as the provider

    - by Jeff
    I have a provider that I'm upgrading from version 2 to version 3. basically a user comes to one of our sites and we say "if you don't have an openID sign up with this one" They click that and are sent to our in house provider what signs them up for an account and has to verify their email address. In the link I send via Email I included the return to url . This way when they click the link to verify their email (sometimes up to a week later) they are sent to our page that knows to send them back to the returnTo to login. I could not find a good way to do this in version 2 so I used a hack. Sadly this hack broke in version 2 so I'm completely stumped as to how to find the login page url that is the return_To Note: I need the full URL not just the domain. old hack: if (ProviderEndpoint.PendingAuthenticationRequest != null) { req = ProviderEndpoint.PendingAuthenticationRequest.ToString(); int startpos = req.LastIndexOf("CheckIdRequest.ReturnTo = '"); startpos += "CheckIdRequest.ReturnTo = '".Length; int endpos = req.LastIndexOf("token=") - startpos-1; if (endpos > 0) { req = req.Substring(startpos, endpos); } else { log.Fatal("Missing token in url" + ProviderEndpoint.PendingAuthenticationRequest.ToString()); return "~/"; } req = req.Replace("&internalLogin=True", ""); req = req.Replace("?internalLogin=True&", "?"); req = req.Replace("?internalLogin=True", ""); }

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  • c++ STL vector is not acccepting the copy constructor

    - by prabhakaran
    I wrote a code ( c++,visual studio 2010) which is having a vector, even I though copy const is declared, but is still showing that copy const is not declared Here the code #include<iostream> #include<vector> using namespace std; class A { public: A(){cout << "Default A is acting" << endl ;} A(A &a){cout << "Copy Constructor of A is acting" << endl ;} }; int main() { A a; A b=a; vector<A> nothing; nothing.push_back(a); int n; cin >> n; } The error I got is Error 1 error C2558: class 'A' : no copy constructor available or copy constructor is declared 'explicit' c:\program files\microsoft visual studio 10.0\vc\include\xmemory 48 1 delete Anybody please help me

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  • Arrays not counting correctly

    - by Nick Gibson
    I know I was just asking a question earlier facepalm This is in Java coding by the way. Well after everyones VERY VERY helpful advice (thank you guys alot) I managed to get over half of the program running how I wanted. Everything is pointing in the arrays where I want them to go. Now I just need to access the arrays so that It prints the correct information randomly. This is the current code that im using: http://pastebin.org/301483 The specific code giving me problems is this: long aa; int abc; for (int i = 0; i < x; i++) { aa = Math.round(Math.random()*10); String str = Long.toString(aa); abc = Integer.parseInt(str); String[] userAnswer = new String[x]; if(abc > x) { JOptionPane.showMessageDialog(null,"Number is too high. \nNumber Generator will reset."); break; } userAnswer[i] = JOptionPane.showInputDialog(null,"Question "+quesNum+"\n"+questions[abc]+"\n\nA: "+a[abc]+"\nB: "+b[abc]+"\nC: "+c[abc]+"\nD: "+d[abc]); answer = userAnswer[i].compareTo(answers[i]); if(answer == 0) { JOptionPane.showMessageDialog(null,"Correct. \nThe Correct Answer is "+answers[abc]+""+i); } else { JOptionPane.showMessageDialog(null,"Wrong. \n The Correct Answer is "+answers[abc]+""+i); }//else

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  • java + increasing performance and scalability

    - by varun
    Hi, below is the a code snippet, which returns the object of a class. now the object is basially comparing to some parameter in loop. my concern is what if there are thousands of objects in loop, in that case performance and scalability can be an issue. please suggest how to improve this code for performance part public Widget get(String name,int major,int minor,boolean exact) { Widget widgetToReturn = null; if(exact) { Widget w = new Widget(name, major, minor); // for loop using JDK 1.5 version for(Widget wid : set) { if((w.getName().equals(wid.getName())) && (wid.getVersion()).equals(w.getVersion())) { widgetToReturn = w; break; } } } else { Widget w = new Widget(name, major, minor); WidgetVersion widgetVersion = new WidgetVersion(major, minor); // for loop using JDK 1.5 version for(Widget wid : set) { WidgetVersion wv = wid.getVersion(); if((w.getName().equals(wid.getName())) && major == wv.getMajor() && WidgetVersion.isCompatibleAndNewer(wv, widgetVersion)) { widgetToReturn = wid; } else if((w.getName().equals(wid.getName())) && wv.equals(widgetVersion.getMajor(), widgetVersion.getMinor())) { widgetToReturn = w; } } } return widgetToReturn; }

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  • Cannot perform an ORDERBY against my EF4 data

    - by Jaxidian
    I have a query hitting EF4 using STEs and I'm having an issue with user-defined sorting. In debugging this, I have removed the dynamic sorting and am hard-coding it and I still have the issue. If I swap/uncomment the var results = xxx lines in GetMyBusinesses(), my results are not sorted any differently - they are always sorting it ascendingly. FYI, Name is a varchar(200) field in SQL 2008 on my Business table. private IQueryable<Business> GetMyBusinesses(MyDBContext CurrentContext) { var myBusinesses = from a in CurrentContext.A join f in CurrentContext.F on a.FID equals f.id join b in CurrentContext.Businesses on f.BID equals b.id where a.PersonID == 52 select b; var results = from r in myBusinesses orderby "Name" ascending select r; //var results = from r in results // orderby "Name" descending // select r; return results; } private PartialEntitiesList<Business> DoStuff() { var myBusinesses = GetMyBusinesses(); var myBusinessesCount = GetMyBusinesses().Count(); Results = new PartialEntitiesList<Business>(myBusinesses.Skip((PageNumber - 1)*PageSize).Take(PageSize).ToList()) {UnpartialTotalCount = myBusinessesCount}; return Results; } public class PartialEntitiesList<T> : List<T> { public PartialEntitiesList() { } public PartialEntitiesList(int capacity) : base(capacity) { } public PartialEntitiesList(IEnumerable<T> collection) : base(collection) { } public int UnpartialTotalCount { get; set; } }

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  • C# ? Can anyone explain the strange behaviour?

    - by partizan
    Hi, guys. Here is the example with comments: class Program { // first version of structure public struct D1 { public double d; public int f; } // during some changes in code then we got D2 from D1 // Field f type became double while it was int before public struct D2 { public double d; public double f; } static void Main(string[] args) { // Scenario with the first version D1 a = new D1(); D1 b = new D1(); a.f = b.f = 1; a.d = 0.0; b.d = -0.0; bool r1 = a.Equals(b); // gives true, all is ok // The same scenario with the new one D2 c = new D2(); D2 d = new D2(); c.f = d.f = 1; c.d = 0.0; d.d = -0.0; bool r2 = c.Equals(d); // false, oops! this is not the result i've expected for } } So, what do you think about this?

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  • User switching without logging off

    - by mrh1967
    We need to switch users without logging off so we can remotely administrate a PC running with a limited user that will disconnect from the VPN if the user logs off. I've got this working by killing the explorer process and then running explorer.exe with the administrator user credentials as the following code shows: private void btnOk_Click(object sender, EventArgs e) { IntPtr tokenHandle = new IntPtr(0); if (LogonUser("administrator", Environment.UserDomainName, txtPassword.Text, 3, 0, ref tokenHandle)) { ProcessStartInfo psi = new ProcessStartInfo(@"C:\Windows\explorer.exe"); psi.UserName = "administrator"; char[] pword = txtPassword.Text.ToCharArray(); psi.Password = new System.Security.SecureString(); foreach (char c in pword) { psi.Password.AppendChar(c); } psi.UseShellExecute = false; psi.LoadUserProfile = true; restartExplorer(psi); this.Close(); } else { MessageBox.Show("Wrong password", "Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); } } private void restartExplorer(ProcessStartInfo psi) { Process[] procs = System.Diagnostics.Process.GetProcesses(); foreach (Process p in procs) { if (p.ProcessName == "explorer") { p.Kill(); break; } } System.Diagnostics.Process.Start(psi); } [DllImport("advapi32.dll", SetLastError = true)] public extern static bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword, int dwLogonType, int dwLogonProvider, ref IntPtr phToken); This code and similar code that does the same but makes the ProcessStartInfo for the limited user works perfectly and allows changing between the limited and administrator accounts without disconnecting the VPN but it has one problem - If we use this to change to the administrator user, make some changes to the system, then change back to the limited user all works ok until the limited user logs off when a blank desktop is displayed until CTRL-ALT-DEL is pressed and the user is logged off again. Because we block CTRL-ALT-DEL the PC effectively hangs until it is powered off. Does anyone know how to stop this from happening so we can change users without the PC hanging when they log off?

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  • http connection timeout issues

    - by Mark
    I'm running into an issue when i try to use the HttpClient connecting to a url. The http connection is taking a longer time to timeout, even after i set a connection timeoout. int timeoutConnection = 5000; HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection); int timeoutSocket = 5000; HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket); It works perfect most of the time. However, every once in while, the http connection runs for ever and ignore the setconnectiontimeout, especailly when the phone is connected to wifi, and the phone was idling. So after the phone is idling, the first time i try to connect, the http connection ignores the setconnectiontimeout and runs forever, after i cancel it and try again, it works like charm everytime. But that one time that doesn't work it creates a threadtimeout error, i tried using a different thread, it works, but i know that the thread is running for long time. I understand that the wifi goes to sleep on idle, but i dont understand why its ignoring the setconnectiontimeout. Anyone can help, id really appreciated.

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  • Adding fields until screen is full

    - by Eric
    For the sake of this question, let us suppose that I want a row of buttons. I want to put as many buttons in that row as I can fit on the screen, but no more. In other words, as long as a prospective button will not be cut off or have its text shortened, add it. It seems that I should be able to do something like: HorizontalFieldManager hfm = new HorizontalFieldManager(); int remainingWidth = Display.getWidth(); int i =0; while(true) { ButtonField bf = new ButtonField("B " + i); remainingWidth -= bf.getWidth(); if(remainingWidth<0) break; hfm.add(bf); i++; } add(hfm); But this doesn't work. bf.getWidth() is always 0. I suspect that this is because the button has not yet been laid out when I query for the width. So, perhaps I could just make sure the buttons are always the same size. But this won't work for a few reasons: Different BB platforms have different looks for buttons and text that will fit on a button on a Curve won't fit on a button on a Storm. 3rd party themes may change the look of buttons, so I can't even count on buttons being a certain size on a certain platform. Is there no way for me to actually check the remaining space before adding a button? It feels like a fairly useful feature; am I just missing something?

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  • Deleting unneeded rows from a table with 2 criteria

    - by stormbreaker
    Hello. I have a many-to-many relations table and I need to DELETE the unneeded rows. The lastviews table's structure is: | user (int) | document (int) | time (datetime) | This table logs the last users which viewed the document. (user, document) is unique. I show only the last 10 views of a document and until now I deleted the unneeded like this: DELETE FROM `lastviews` WHERE `document` = ? AND `user` NOT IN (SELECT * FROM (SELECT `user` FROM `lastviews` WHERE `document` = ? ORDER BY `time` DESC LIMIT 10) AS TAB) However, now I need to also show the last 5 documents a user has viewed. This means I can no longer delete rows using the previous query because it might delete information I need (say a user didn't view documents in 5 minutes and the rows are deleted) To sum up, I need to delete all the records that don't fit these 2 criterias: SELECT ... FROM `lastviews` WHERE `document` = ? ORDER BY `time` DESC LIMIT 10 and SELECT * FROM `lastviews` WHERE `user` = ? ORDER BY `time` DESC LIMIT 0, 5 I need the logic. Thanks in advance.

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  • replacing elements horizontally and vertically in a 2D array

    - by wello horld
    the code below ask for the user's input for the 2D array size and prints out something like this: (say an 18x6 grid) .................. .................. .................. .................. .................. .................. code starts here: #include <stdio.h> #define MAX 10 int main() { char grid[MAX][MAX]; int i,j,row,col; printf("Please enter your grid size: "); scanf("%d %d", &row, &col); for (i = 0; i < row; i++) { for (j = 0; j < col; j++) { grid[i][j] = '.'; printf("%c ", grid[i][j]); } printf("\n"); } return 0; } I now ask the user for a string, then ask them where to put it for example: Please enter grid size: 18 6 Please enter word: Hello Please enter location: 0 0 Output: Hello............. .................. .................. .................. .................. .................. Please enter location: 3 4 Output: .................. .................. .................. ..Hello........... .................. .................. program just keeps going. Any thoughts on how to modify the code for this? PS: Vertical seems way hard, but I want to start on horizontal first to have something to work on.

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  • im counting the number of characters in a file but i want to count the number of words that are less

    - by user320950
    i want to do this: reads the words in the file one at a time. (Use a string to do this) Counts three things: how many single-character words are in the file, how many short (2 to 5 characters) words are in the file, and how many long (6 or more characters) words are in the file. HELP HERE im not sure on how about reading file into a string. i know i have to something like this but i dont understand the rest. HELP HERE ifstream infile; //char mystring[6]; //char mystring[20]; int main() { infile.open("file.txt"); if(infile.fail()) { cout << " Error " << endl; } int numb_char=0; char letter; while(!infile.eof()) { infile.get(letter); cout << letter; numb_char++; break; } cout << " the number of characters is :" << numb_char << endl; infile.close(); return 0;

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  • symfony + doctrine + inheritance, how to make them work?

    - by imac
    I am beginning to work with Symfony, I've found some documentation about inheritance. But also found this discouraging article, which make me doubt if Doctrine handles inheritance any good at all... Has anyone find a smart solution for inheritance in Symfony+Doctrine? As an example, I have already structured the database something like this: CREATE TABLE `poster` ( `poster_id` int(11) NOT NULL AUTO_INCREMENT, `user_name` varchar(50) NOT NULL, PRIMARY KEY (`poster_id`), UNIQUE KEY `id` (`poster_id`), ) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=latin1; CREATE TABLE `user` ( `user_id` int(11) NOT NULL, `real_name` varchar(50) DEFAULT NULL, PRIMARY KEY (`user_id`), UNIQUE KEY `user_id` (`user_id`), CONSTRAINT `user_fk` FOREIGN KEY (`user_id`) REFERENCES `poster` (`poster_id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; From that, Doctrine generated this "schema.yml": Poster: connection: doctrine tableName: poster columns: poster_id: type: integer(4) fixed: false unsigned: false primary: true autoincrement: true user_name: type: string(50) fixed: false unsigned: false primary: false notnull: true autoincrement: false relations: Post: local: poster_id foreign: poster_id type: many User: local: poster_id foreign: user_id type: many Version: local: poster_id foreign: poster_id type: many User: connection: doctrine tableName: user columns: user_id: type: integer(4) fixed: false unsigned: false primary: true autoincrement: false real_name: type: string(50) fixed: false unsigned: false primary: false notnull: false autoincrement: false relations: Poster: local: user_id foreign: poster_id type: one User creation for this structure with Doctrine auto-generated forms does not work. Any clue will be appreciated.

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  • How do I handle freeing unmanaged structures on application close?

    - by LostKaleb
    I have a C# project in which i use several unmanaged C++ functions. More so, I also have static IntPtr that I use as parameters for those functions. I know that whenever I use them, I should implement IDisposable in that class and use a destructor to invoke the Dispose method, where I free the used IntPtr, as is said in the MSDN page. public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } private void Dispose(bool disposing) { // Check to see if Dispose has already been called. if (!this.disposed) { if (disposing) { component.Dispose(); } CloseHandle(m_InstanceHandle); m_InstanceHandle = IntPtr.Zero; disposed = true; } } [System.Runtime.InteropServices.DllImport("Kernel32")] private extern static Boolean CloseHandle(IntPtr handle); However, when I terminate the application, I'm still left with a hanging process in TaskManager. I believe that it must be related to the used of the MarshalAs instruction in my structures: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; } When I create such a structure should I also be careful to free the space it allocs using a destructor? [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; ~SipxAudioCodec() { Marshal.FreeGlobal(something...); } }

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  • how to do validations when composing object of a class in other class ?

    - by haansi
    Hi, I have an IPAddress class which has one property named ip and in its setter I am validating data coming and if data is invalid it throws an error. (Its code is as the following): private string ip; public string IP { get { return ip; } set { string PartsOfIP = value.Split('.'); if (PartsOfIP.Length == 4) { foreach (string part in PartsOfIP) { int a = 0; bool result = int.TryParse(part, out a); if (result != true) { throw new Exception("Invalid IP"); } else { ip = value; } } } else { throw new Exception("Invalid IP"); } } In User Class I want to compose an object of IPAddress class. I am doing validations for properties of User in User class and validations of Ip in IPAddress class. My question is how I will compose IPAddress object in UserClass and what will be syntax for this ? If I again mention get and set here with IPAddress object in User class will my earlier mentioned (in IPAddress class) getter and setter work ? plz advice me in details thanks

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  • how to fill missing values from a list

    - by Stephane
    I have an object containing a date and a count. public class Stat { public DateTime Stamp {get; set;} public int Count {get; set ;} } I have a Serie object that holds a list of thoses Stat plus some more info such as name and so on... public class Serie { public string Name { get; set; } public List<Stat> Data { get; set; } ... } Consider that I have a List of Serie but the series don't all contain the same Stamps. I need to fill in the missing stamps in all series with a default value. I thought of an extension method with signature like this (please provide better name if you find one :) ) : public static IEnumerable<Serie> Equalize(this IEnumerable<ChartSerie> series, int defaultCount) this question seems to treat the same problem, but when querying directly the DB. of course I could loop through the dates and create another list. But is there any more elegant way to achieve this? i.e.: Serie A: 01.05.2010 1 03.05.2010 3 Serie B: 01.05.2010 5 02.05.2010 6 I should get : Serie A : 01.05.2010 1 02.05.2010 0 03.05.2010 3 Serie B: 01.05.2010 5 02.05.2010 6 03.05.2010 0

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  • draw rectangle in millimeters doesnt show accurate width

    - by user338081
    I am drawing a rectangle in millimeter on a panel using the following code in c# by entering the width and length in mm at runtime. however the resultant rectangle drawn varies in size in different monitors. I want the rectangle to appear same size irrespective of the running the app in any monitor. Can any1 help me?. currently the width for 10mm measures 12mm and length for 10mm shows 11mm using a scale. I tested the appn on different monitors, there again it shows different length. Is ther anyway that i can show it to be of same width and length? void panel1_Paint(object sender, PaintEventArgs e) { SolidBrush ygBrush = new SolidBrush(Color.YellowGreen); g = panel1.CreateGraphics(); g.PageUnit = GraphicsUnit.Millimeter; int w = Int32.Parse(textBox1.Text.ToString()); int h = Int32.Parse(textBox2.Text.ToString()); rct = new Rectangle(94, 27, w, h); g.FillRectangle(ygBrush, rct); }

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  • how to skip first 3 row of text file.

    - by Dilantha Chamal
    hey when i reading the text file using java, how can i skip first 3 rows of the text file. Show me how to do that. public class Reader { public static void main(String[] args) { BufferedReader reader; try { reader = new BufferedReader(new InputStreamReader( new FileInputStream("sample.txt"))); Map<String, Integer result = new LinkedHashMap<String, Integer(); Map<String, Integer result2 = new LinkedHashMap<String, Integer(); while (reader.ready()) { String line = reader.readLine(); /split a line with spaces/ String[] values = line.split("\s+"); /set a key date\tanimal/ String key = values[0] + "\t" + values[1]; int sum = 0; int count = 0; /get a last counter and sum/ if (result.containsKey(key)) { sum = result.get(key); count = result2.get(key); } else{ } /increment sum a count and save in the map with key/ result.put(key, sum + Integer.parseInt(values[2])); result2.put(key, count + 1); } /interate and print new output/ for (String key : result.keySet()) { Integer sum = result.get(key); Integer count = result2.get(key); System.out.println(key + " " + sum + "\t" + count); } reader.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }

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  • Using boost::random to select from an std::list where elements are being removed

    - by user144182
    See this related question on more generic use of the Boost Random library. My questions involves selecting a random element from an std::list, doing some operation, which could potentally include removing the element from the list, and then choosing another random element, until some condition is satisfied. The boost code and for loop look roughly like this: // create and insert elements into list std::list<MyClass> myList; //[...] // select uniformly from list indices boost::uniform_int<> indices( 0, myList.size()-1 ); boost::variate_generator< boost::mt19937, boost::uniform_int<> > selectIndex(boost::mt19937(), indices); for( int i = 0; i <= maxOperations; ++i ) { int index = selectIndex(); MyClass & mc = myList.begin() + index; // do operations with mc, potentially removing it from myList //[...] } My problem is as soon as the operations that are performed on an element result in the removal of an element, the variate_generator has the potential to select an invalid index in the list. I don't think it makes sense to completely recreate the variate_generator each time, especially if I seed it with time(0).

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  • how do I remove rows/columns from this matrix using python

    - by banditKing
    My matrix looks like this. ['Hotel', ' "excellent"', ' "very good"', ' "average"', ' "poor"', ' "terrible"', ' "cheapest"', ' "rank"', ' "total reviews"'] ['westin', ' 390', ' 291', ' 70', ' 43', ' 19', ' 215', ' 27', ' 813'] ['ramada', ' 136', ' 67', ' 53', ' 30', ' 24', ' 149', ' 49', ' 310 '] ['sutton place', '489', ' 293', ' 106', ' 39', ' 20', ' 299', ' 24', ' 947'] ['loden', ' 681', ' 134', ' 17', ' 5', ' 0', ' 199', ' 4', ' 837'] ['hampton inn downtown', ' 241', ' 166', ' 26', ' 5', ' 1', ' 159', ' 21', ' 439'] ['shangri la', ' 332', ' 45', ' 20', ' 8', ' 2', ' 325', ' 8', ' 407'] ['residence inn marriott', ' 22', ' 15', ' 5', ' 0', ' 0', ' 179', ' 35', ' 42'] ['pan pacific', ' 475', ' 262', ' 86', ' 29', ' 16', ' 249', ' 15', ' 868'] ['sheraton wall center', ' 277', ' 346', ' 150', ' 80', ' 26', ' 249', ' 45', ' 879'] ['westin bayshore', ' 390', ' 291', ' 70', ' 43', ' 19', ' 199', ' 813'] I want to remove the top row and the 0th column from this and create a new matrix. How do I do this? Normally in java or so Id use the following code: for (int y; y< matrix[x].length; y++) for(int x; x < matrix[Y].length; x++) { if(x == 0 || y == 0) { continue } else { new_matrix[x][y] = matrix[x][y]; } } Is there a way such as this in python to iterate and selectively copy elements? Thanks EDIT Im also trying to convert each matrix element from a string to a float as I iterate over the matrix. This my updated modified code based on the answer below. A = [] f = open("csv_test.csv",'rt') try: reader = csv.reader(f) for row in reader: A.append(row) finally: f.close() new_list = [row[1:] for row in A[1:]] l = np.array(new_list) l.astype(np.float32) print l However Im getting an error --> l.astype(np.float32) print l ValueError: setting an array element with a sequence.

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  • Java iterative vs recursive

    - by user1389813
    Can anyone explain why the following recursive method is faster than the iterative one (Both are doing it string concatenation) ? Isn't the iterative approach suppose to beat up the recursive one ? plus each recursive call adds a new layer on top of the stack which can be very space inefficient. private static void string_concat(StringBuilder sb, int count){ if(count >= 9999) return; string_concat(sb.append(count), count+1); } public static void main(String [] arg){ long s = System.currentTimeMillis(); StringBuilder sb = new StringBuilder(); for(int i = 0; i < 9999; i++){ sb.append(i); } System.out.println(System.currentTimeMillis()-s); s = System.currentTimeMillis(); string_concat(new StringBuilder(),0); System.out.println(System.currentTimeMillis()-s); } I ran the program multiple time, and the recursive one always ends up 3-4 times faster than the iterative one. What could be the main reason there that is causing the iterative one slower ?

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  • ProgressDialog won't show, even in onPreExecute of AsyncTask

    - by Geltrude
    In my class, Main extends Activity, I've this: @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); switch (requestCode) { case ... case CREDENTIAL_VIEW: new SetStatusProgressBar(this).execute(); And there is this nested class: private class SetStatusProgressBar extends AsyncTask<String, Void, Boolean> { private ProgressDialog dialog; private Main ctx; public SetStatusProgressBar(Main ctx) { this.ctx = ctx; dialog = new ProgressDialog(ctx); } // progress dialog to show user that contacting server. protected void onPreExecute() { this.dialog = ProgressDialog.show(ctx, null, "Refreshing data from server...", true, false); } @Override protected void onPostExecute(final Boolean success) { //... //statements that refresh UI //... if (dialog.isShowing()) { dialog.dismiss(); timerProgressBarStop(); } } protected Boolean doInBackground(final String... args) { //... //statements to download data from server //... return true; } } In the Main class I open a second Activity, in this way: Intent myIntent = new Intent(Main.this, Credentials.class); startActivityForResult(myIntent, CREDENTIAL_VIEW); That second Activity returns to the Main activity in this way: Intent intent = new Intent(); setResult(RESULT_OK, intent); finish(); I don't understand why when I navigate from the second Activity to the Main, the ProgressDialog will show ONLY AFTER that the UI refreshes... In this way the Progress Dialog stays on the screen only for half second... and then hides! :( I'd like to see the ProgressDialog on top during all the download time! Help, please. Thank you all

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  • MySQL Join/Comparison on a DATETIME column (<5.6.4 and > 5.6.4)

    - by Simon
    Suppose i have two tables like so: Events ID (PK int autoInc), Time (datetime), Caption (varchar) Position ID (PK int autoinc), Time (datetime), Easting (float), Northing (float) Is it safe to, for example, list all the events and their position if I am using the Time field as my joining criteria? I.e.: SELECT E.*,P.* FROM Events E JOIN Position P ON E.Time = P.Time OR, even just simply comparing a datetime value (taking into consideration that the parameterized value may contain the fractional seconds part - which MySQL has always accepted) e.g. SELECT E.* FROM Events E WHERE E.Time = @Time I understand MySQL (before version 5.6.4) only stores datetime fields WITHOUT milliseconds. So I would assume this query would function OK. However as of version 5.6.4, I have read MySQL can now store milliseconds with the datetime field. Assuming datetime values are inserted using functions such as NOW(), the milliseconds are truncated (<5.6.4) which I would assume allow the above query to work. However, with version 5.6.4 and later, this could potentially NOT work. I am, and only ever will be interested in second accuracy. If anyone could answer the following questions would be greatly appreciated: In General, how does MySQL compare datetime fields against one another (consider the above query). Is the above query fine, and does it make use of indexes on the time fields? (MySQL < 5.6.4) Is there any way to exclude milliseconds? I.e. when inserting and in conditional joins/selects etc? (MySQL 5.6.4) Will the join query above work? (MySQL 5.6.4) EDIT I know i can cast the datetimes, thanks for those that answered, but i'm trying to tackle the root of the problem here (the fact that the storage type/definition has been changed) and i DO NOT want to use functions in my queries. This negates all my work of optimizing queries applying indexes etc, not to mention having to rewrite all my queries. EDIT2 Can anyone out there suggest a reason NOT to join on a DATETIME field using second accuracy?

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  • Strange performance behaviour

    - by plastilino
    I'm puzzled with this. In my machine Direct calculation: 375 ms Method calculation: 3594 ms, about TEN times SLOWER If I place the method calulation BEFORE the direct calculation, both times are SIMILAR. Woud you check it in your machine? class Test { static long COUNT = 50000 * 10000; private static long BEFORE; /*--------METHOD---------*/ public static final double hypotenuse(double a, double b) { return Math.sqrt(a * a + b * b); } /*--------TIMER---------*/ public static void getTime(String text) { if (BEFORE == 0) { BEFORE = System.currentTimeMillis(); return; } long now = System.currentTimeMillis(); long elapsed = (now - BEFORE); BEFORE = System.currentTimeMillis(); if (text.equals("")) { return; } String message = "\r\n" + text + "\r\n" + "Elapsed time: " + elapsed + " ms"; System.out.println(message); } public static void main(String[] args) { double a = 0.2223221101; double b = 122333.167; getTime(""); /*--------DIRECT CALCULATION---------*/ for (int i = 1; i < COUNT; i++) { Math.sqrt(a * a + b * b); } getTime("Direct: "); /*--------METHOD---------*/ for (int k = 1; k < COUNT; k++) { hypotenuse(a, b); } getTime("Method: "); } }

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