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  • Interpolation of time series data in R

    - by Pierreten
    I'm not sure what i'm missing here, but i'm basically trying to compute interpolated values for a time series; when I directly plot the series, constraining the interpolation points with "interpolation.date.vector", the plot is correct: plot(date.vector,fact.vector,ylab='Quantity') lines(spline(date.vector,fact.vector,xout=interpolation.date.vector)) When I compute the interpolation, store it in an intermediate variable, and then plot the results; I get a radically incorrect result: intepolated.values <- spline(date.vector,fact.vector,xout=interpolation.date.vector) plot(intepolated.values$x,intepolated.values$y) lines(testinterp$x,testinterp$y) Doesn't the lines() function have to execute the spline() function to retrieve the interpolated points in the same way i'm doing it?

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  • C - check if string is a substring of another string

    - by user69514
    I need to write a program that takes two strings as arguments and check if the second one is a substring of the first one. I need to do it without using any special library functions. I created this implementation, but I think it's always returning true as long as there is one letter that's the same in both strings. Can you help me out here. I'm not sure what I am doing wrong: #include <stdio.h> #include <string.h> int my_strstr( char const *s, char const *sub ) { char const *ret = sub; int r = 0; while ( ret = strchr( ret, *sub ) ) { if ( strcmp( ++ret, sub+1 ) == 0 ){ r = 1; } else{ r = 0; } } return r; } int main(int argc, char **argv){ if (argc != 3) { printf ("Usage: check <string one> <string two>\n"); } int result = my_strstr(argv[1], argv[2]); if(result == 1){ printf("%s is a substring of %s\n", argv[2], argv[1]); } else{ printf("%s is not a substring of %s\n", argv[2], argv[1]); } return 0; }

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  • PHP string manipulation, inside the string

    - by James
    I have string: ABCDEFGHIJK And I have two arrays of positions in that string that I want to insert different things to. Array ( [0] => 0 [1] => 5 ) Array ( [0] => 7 [1] => 9 ) Which if I decided to add the # character and the = character, it'd produce: #ABCDE=FG#HI=JK Is there any way I can do this without a complicated set of substr? Also, # and = need to be variables that can be of any length, not just one character.

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  • C string question

    - by user208454
    I am writing a simple c program which reverses a string, taking the string from argv[1]. Here is the code: #include <stdio.h> #include <stdlib.h> #include <string.h> char* flip_string(char *string){ int i = strlen(string); int j = 0; // Doesn't really matter all I wanted was the same size string for temp. char* temp = string; puts("This is the original string"); puts(string); puts("This is the \"temp\" string"); puts(temp); for(i; i>=0; i--){ temp[j] = string[i] if (j <= strlen(string)) { j++; } } return(temp); } int main(int argc, char *argv[]){ puts(flip_string(argv[1])); printf("This is the end of the program\n"); } That's basically it, the program compiles and everything but does not return the temp string in the end (just blank space). In the beginning it prints temp fine when its equal to string. Furthermore if I do a character by character printf of temp in the for loop the correct temp string in printed i.e. string - reversed. just when I try to print it to standard out (after the for loop/ or in the main) nothing happens only blank space is printed.

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  • Segfault when iterating over a map<string, string> and drawing its contents using SDL_TTF

    - by Michael Stahre
    I'm not entirely sure this question belongs on gamedev.stackexchange, but I'm technically working on a game and working with SDL, so it might not be entirely offtopic. I've written a class called DebugText. The point of the class is to have a nice way of printing values of variables to the game screen. The idea is to call SetDebugText() with the variables in question every time they change or, as is currently the case, every time the game's Update() is called. The issue is that when iterating over the map that contains my variables and their latest updated values, I get segfaults. See the comments in DrawDebugText() below, it specifies where the error happens. I've tried splitting the calls to it-first and it-second into separate lines and found that the problem doesn't always happen when calling it-first. It alters between it-first and it-second. I can't find a pattern. It doesn't fail on every call to DrawDebugText() either. It might fail on the third time DrawDebugText() is called, or it might fail on the fourth. Class header: #ifndef CLIENT_DEBUGTEXT_H #define CLIENT_DEBUGTEXT_H #include <Map> #include <Math.h> #include <sstream> #include <SDL.h> #include <SDL_ttf.h> #include "vector2.h" using std::string; using std::stringstream; using std::map; using std::pair; using game::Vector2; namespace game { class DebugText { private: TTF_Font* debug_text_font; map<string, string>* debug_text_list; public: void SetDebugText(string var, bool value); void SetDebugText(string var, float value); void SetDebugText(string var, int value); void SetDebugText(string var, Vector2 value); void SetDebugText(string var, string value); int DrawDebugText(SDL_Surface*, SDL_Rect*); void InitDebugText(); void Clear(); }; } #endif Class source file: #include "debugtext.h" namespace game { // Copypasta function for handling the toString conversion template <class T> inline string to_string (const T& t) { stringstream ss (stringstream::in | stringstream::out); ss << t; return ss.str(); } // Initializes SDL_TTF and sets its font void DebugText::InitDebugText() { if(TTF_WasInit()) TTF_Quit(); TTF_Init(); debug_text_font = TTF_OpenFont("LiberationSans-Regular.ttf", 16); TTF_SetFontStyle(debug_text_font, TTF_STYLE_NORMAL); } // Iterates over the current debug_text_list and draws every element on the screen. // After drawing with SDL you need to get a rect specifying the area on the screen that was changed and tell SDL that this part of the screen needs to be updated. this is done in the game's Draw() function // This function sets rects_to_update to the new list of rects provided by all of the surfaces and returns the number of rects in the list. These two parameters are used in Draw() when calling on SDL_UpdateRects(), which takes an SDL_Rect* and a list length int DebugText::DrawDebugText(SDL_Surface* screen, SDL_Rect* rects_to_update) { if(debug_text_list == NULL) return 0; if(!TTF_WasInit()) InitDebugText(); rects_to_update = NULL; // Specifying the font color SDL_Color font_color = {0xff, 0x00, 0x00, 0x00}; // r, g, b, unused int row_count = 0; string line; // The iterator variable map<string, string>::iterator it; // Gets the iterator and iterates over it for(it = debug_text_list->begin(); it != debug_text_list->end(); it++) { // Takes the first value (the name of the variable) and the second value (the value of the parameter in string form) //---------THIS LINE GIVES ME SEGFAULTS----- line = it->first + ": " + it->second; //------------------------------------------ // Creates a surface with the text on it that in turn can be rendered to the screen itself later SDL_Surface* debug_surface = TTF_RenderText_Solid(debug_text_font, line.c_str(), font_color); if(debug_surface == NULL) { // A standard check for errors fprintf(stderr, "Error: %s", TTF_GetError()); return NULL; } else { // If SDL_TTF did its job right, then we now set a destination rect row_count++; SDL_Rect dstrect = {5, 5, 0, 0}; // x, y, w, h dstrect.x = 20; dstrect.y = 20*row_count; // Draws the surface with the text on it to the screen int res = SDL_BlitSurface(debug_surface,NULL,screen,&dstrect); if(res != 0) { //Just an error check fprintf(stderr, "Error: %s", SDL_GetError()); return NULL; } // Creates a new rect to specify the area that needs to be updated with SDL_Rect* new_rect_to_update = (SDL_Rect*) malloc(sizeof(SDL_Rect)); new_rect_to_update->h = debug_surface->h; new_rect_to_update->w = debug_surface->w; new_rect_to_update->x = dstrect.x; new_rect_to_update->y = dstrect.y; // Just freeing the surface since it isn't necessary anymore SDL_FreeSurface(debug_surface); // Creates a new list of rects with room for the new rect SDL_Rect* newtemp = (SDL_Rect*) malloc(row_count*sizeof(SDL_Rect)); // Copies the data from the old list of rects to the new one memcpy(newtemp, rects_to_update, (row_count-1)*sizeof(SDL_Rect)); // Adds the new rect to the new list newtemp[row_count-1] = *new_rect_to_update; // Frees the memory used by the old list free(rects_to_update); // And finally redirects the pointer to the old list to the new list rects_to_update = newtemp; newtemp = NULL; } } // When the entire map has been iterated over, return the number of lines that were drawn, ie. the number of rects in the returned rect list return row_count; } // The SetDebugText used by all the SetDebugText overloads // Takes two strings, inserts them into the map as a pair void DebugText::SetDebugText(string var, string value) { if (debug_text_list == NULL) { debug_text_list = new map<string, string>(); } debug_text_list->erase(var); debug_text_list->insert(pair<string, string>(var, value)); } // Writes the bool to a string and calls SetDebugText(string, string) void DebugText::SetDebugText(string var, bool value) { string result; if (value) result = "True"; else result = "False"; SetDebugText(var, result); } // Does the same thing, but uses to_string() to convert the float void DebugText::SetDebugText(string var, float value) { SetDebugText(var, to_string(value)); } // Same as above, but int void DebugText::SetDebugText(string var, int value) { SetDebugText(var, to_string(value)); } // Vector2 is a struct of my own making. It contains the two float vars x and y void DebugText::SetDebugText(string var, Vector2 value) { SetDebugText(var + ".x", to_string(value.x)); SetDebugText(var + ".y", to_string(value.y)); } // Empties the list. I don't actually use this in my code. Shame on me for writing something I don't use. void DebugText::Clear() { if(debug_text_list != NULL) debug_text_list->clear(); } }

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  • C# adding string elements of 4 different string arrays with each other

    - by new_coder
    Hello. I need an advice about how to create new string array from 4 different string arrays: We have 4 string arrays: string[] arr1 = new string [] {"a1","a2","a3"..., "a30"}; string[] arr2 = new string [] {"d10","d11","d12","d13","d14","d15"}; string[] arr3 = new string [] {"f1","f2","f3"...,"f20"}; string[] arr4 = new string [] {"s10","s11","s12","s13","s14"}; We need to add all string elements of all 4 arrays with each other like this: a1+d10+f1+s10 a2+d10+f1+s10 ... a1+d11+f1+s10 a2+d11+f1+s10 ... a30+d15+f20+s14 I mean all combinations in that order : arr1_element, arr2_element, arr3_element, arr4_element So the result array would be like that: string[] arr5 = new string [] {"a1d10f1s10","a2d10f1s10 "....}; Any help would be good Thank you

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  • Rotation Interpolation

    - by Rob
    Hello, NB: I'll present this question in degrees purely for simplicity, radians, degrees, different zero-bearing, the problem is essentially the same. Does anyone have any ideas on the code behind rotational interpolation? Given a linear interpolation function: Lerp(from, to, amount), where amount is 0...1 which returns a value between from and to, by amount. How could I apply this same function to a rotational interpolation between 0 and 360 degrees? Given that degrees should not be returned outside 0 and 360. Given this unit circle for degrees: where from = 45 and to = 315, the algorithm should take the shortest path to the angle, i.e. it should go through zero, to 360 and then to 315 - and not all the way round 90, 180, 270 to 315. Is there a nice way to achieve this? Or is it going to just be a horrid mess of if() blocks? Am I missing some well understood standard way of doing this? Any help would be appreciated.

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  • How does interpolation actually work to smooth out an object's movement?

    - by user22241
    I've asked a few similar questions over the past 8 months or so with no real joy, so I am going make the question more general. I have an Android game which is OpenGL ES 2.0. within it I have the following Game Loop: My loop works on a fixed time step principle (dt = 1 / ticksPerSecond) loops=0; while(System.currentTimeMillis() > nextGameTick && loops < maxFrameskip){ updateLogic(dt); nextGameTick+=skipTicks; timeCorrection += (1000d/ticksPerSecond) % 1; nextGameTick+=timeCorrection; timeCorrection %=1; loops++; } render(); My intergration works like this: sprite.posX+=sprite.xVel*dt; sprite.posXDrawAt=sprite.posX*width; Now, everything works pretty much as I would like. I can specify that I would like an object to move across a certain distance (screen width say) in 2.5 seconds and it will do just that. Also because of the frame skipping that I allow in my game loop, I can do this on pretty much any device and it will always take 2.5 seconds. Problem However, the problem is that when a render frame skips, the graphic stutter. It's extremely annoying. If I remove the ability to skip frames, then everything is smooth as you like, but will run at different speeds on different devices. So it's not an option. I'm still not sure why the frame skips, but I would like to point out that this is Nothing to do with poor performance, I've taken the code right back to 1 tiny sprite and no logic (apart from the logic required to move the sprite) and I still get skipped frames. And this is on a Google Nexus 10 tablet (and as mentioned above, I need frame skipping to keep the speed consistent across devices anyway). So, the only other option I have is to use interpolation (or extrapolation), I've read every article there is out there but none have really helped me to understand how it works and all of my attempted implementations have failed. Using one method I was able to get things moving smoothly but it was unworkable because it messed up my collision. I can foresee the same issue with any similar method because the interpolation is passed to (and acted upon within) the rendering method - at render time. So if Collision corrects position (character now standing right next to wall), then the renderer can alter it's position and draw it in the wall. So I'm really confused. People have said that you should never alter an object's position from within the rendering method, but all of the examples online show this. So I'm asking for a push in the right direction, please do not link to the popular game loop articles (deWitters, Fix your timestep, etc) as I've read these multiple times. I'm not asking anyone to write my code for me. Just explain please in simple terms how Interpolation actually works with some examples. I will then go and try to integrate any ideas into my code and will ask more specific questions if need-be further down the line. (I'm sure this is a problem many people struggle with).

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  • Akima interpolation of an array of doubles

    - by David Rutten
    Assuming I have an array of doubles, what's a good algorithm to sample this series using Akima interpolation? I'm too stupid to translate that mathematical description into code. // values is an array of doubles // idx is the index of the left-hand value for the current interpolation // t is the normalized parameter between values[idx] and values[idx+1] // Don't worry about array bounds, I'll handle that separately. public double InterpolateAkima(double[] values, int idx, double t) { ...? }

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  • Complex string split in Java

    - by c0mrade
    Consider the following String : 5|12345|value1|value2|value3|value4+5|777|value1|value2|value3|value4?5|777|value1|value2|value3|value4+ Here is how I want to split string, split it with + so I get this result : myArray[0] = "5|12345|value1|value2|value3|value4"; myArray[1] = "5|777|value1|value2|value3|value4?5|777|value1|value2|value3|value4"; if string has doesn't contain char "?" split it with "|" and continue to part II, if string does contain "?" split it and for each part split it with "|" and continue to part II. Here is part II : myObject.setAttribute1(newString[0]); ... myObject.setAttribute4(newString[3]); Here what I've got so far : private static String input = "5|12345|value1|value2|value3|value4+5|777|value1|value2|value3|value4?5|777|value1|value2|value3|value4+"; public void mapObject(String input){ String[] myArray = null; if (input.contains("+")) { myArray = input.split("+"); } else { myArray = new String[1]; myArray[0] = input; } for (int i = 0; i < myArray.length; i++) { String[] secondaryArray = null; String[] myObjectAttribute = null; if (myArray[i].contains("?")) { secondaryArray = temporaryString.myArray[i].split("?"); for (String string : secondaryArray) { myObjectAttribute = string.split("\\|"); } } else { myObjectAttribute = myArray[i].toString().split("\\|"); } myObject.setAttribute1(myObjectAttribute[0]); ... myObject.setAttribute4(myObjectAttribute[3]); System.out.println(myObject.toString()); } Problem : When I split myArray, going trough for with myArray[0], everything set up nice as it should. Then comes the myArray[1], its split into two parts then the second part overrides the value of the first(how do I know that?). I've overridden toString() method of myObject, when I finish I print the set values so I know that it overrides it, does anybody know how can I fix this?

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  • C# vector class - Interpolation design decision

    - by Benjamin
    Currently I'm working on a vector class in C# and now I'm coming to the point, where I've to figure out, how i want to implement the functions for interpolation between two vectors. At first I came up with implementing the functions directly into the vector class... public class Vector3D { public static Vector3D LinearInterpolate(Vector3D vector1, Vector3D vector2, double factor) { ... } public Vector3D LinearInterpolate(Vector3D other, double factor { ... } } (I always offer both: a static method with two vectors as parameters and one non-static, with only one vector as parameter) ...but then I got the idea to use extension methods (defined in a seperate class called "Interpolation" for example), since interpolation isn't really a thing only available for vectors. So this could be another solution: public class Vector3D { ... } public static class Interpolation { public static Vector3D LinearInterpolate(this Vector3D vector, Vector3D other, double factor) { ... } } So here an example how you'd use the different possibilities: { var vec1 = new Vector3D(5, 3, 1); var vec2 = new Vector3D(4, 2, 0); Vector3D vec3; vec3 = vec1.LinearInterpolate(vec2, 0.5); //1 vec3 = Vector3D.LinearInterpolate(vec1, vec2, 0.5); //2 //or with extension-methods vec3 = vec1.LinearInterpolate(vec2, 0.5); //3 (same as 1) vec3 = Interpolation.LinearInterpolation(vec1, vec2, 0.5); //4 } So I really don't know which design is better. Also I don't know if there's an ultimate rule for things like this or if it's just about what someone personally prefers. But I really would like to hear your opinions, what's better (and if possible why ).

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  • Random String Generator creates same string on multiple calls

    - by rockinthesixstring
    Hi there. I've build a random string generator but I'm having a problem whereby if I call the function multiple times say in a Page_Load method, the function returns the same string twice. here's the code ''' <summary>' ''' Generates a Random String' ''' </summary>' ''' <param name="n">number of characters the method should generate</param>' ''' <param name="UseSpecial">should the method include special characters? IE: # ,$, !, etc.</param>' ''' <param name="SpecialOnly">should the method include only the special characters and excludes alpha numeric</param>' ''' <returns>a random string n characters long</returns>' Public Function GenerateRandom(ByVal n As Integer, Optional ByVal UseSpecial As Boolean = True, Optional ByVal SpecialOnly As Boolean = False) As String Dim chars As String() ' a character array to use when generating a random string' Dim ichars As Integer = 74 'number of characters to use out of the chars string' Dim schars As Integer = 0 ' number of characters to skip out of the characters string' chars = { _ "A", "B", "C", "D", "E", "F", _ "G", "H", "I", "J", "K", "L", _ "M", "N", "O", "P", "Q", "R", _ "S", "T", "U", "V", "W", "X", _ "Y", "Z", "0", "1", "2", "3", _ "4", "5", "6", "7", "8", "9", _ "a", "b", "c", "d", "e", "f", _ "g", "h", "i", "j", "k", "l", _ "m", "n", "o", "p", "q", "r", _ "s", "t", "u", "v", "w", "x", _ "y", "z", "!", "@", "#", "$", _ "%", "^", "&", "*", "(", ")", _ "-", "+"} If Not UseSpecial Then ichars = 62 ' only use the alpha numeric characters out of "char"' If SpecialOnly Then schars = 62 : ichars = 74 ' skip the alpha numeric characters out of "char"' Dim rnd As New Random() Dim random As String = String.Empty Dim i As Integer = 0 While i < n random += chars(rnd.[Next](schars, ichars)) System.Math.Max(System.Threading.Interlocked.Increment(i), i - 1) End While rnd = Nothing Return random End Function but if I call something like this Dim str1 As String = GenerateRandom(5) Dim str2 As String = GenerateRandom(5) the response will be something like this g*3Jq g*3Jq and the second time I call it, it will be 3QM0$ 3QM0$ What am I missing? I'd like every random string to be generated as unique.

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  • Replace apostrophe in json string with empty string

    - by user572844
    Hi, I have problem with deserialization of json string, because string is bad format. For example json object consist string property statusMessage with value "Hello "dog" ". The correct format should be "Hello \" dog \" " . I would like remove apostrophes from this property. Something Like this. "Hello "dog" ". - "Hello dog ". Here is it original json string which I work. "{\"jancl\":{\"idUser\":18438201,\"nick\":\"JANCl\",\"photo\":\"1\",\"sex\":1,\"photoAlbums\":1,\"videoAlbums\":0,\"sefNick\":\"jancl\",\"profilPercent\":75,\"emphasis\":false,\"age\":\"-\",\"isBlocked\":false,\"PHOTO\":{\"normal\":\"http://u.aimg.sk/fotky/1843/82/n_18438201.jpg?v=1\",\"medium\":\"http://u.aimg.sk/fotky/1843/82/m_18438201.jpg?v=1\",\"24x24\":\"http://u.aimg.sk/fotky/1843/82/s_18438201.jpg?v=1\"},\"PLUS\":{\"active\":false,\"activeTo\":\"0000-00-00\"},\"LOCATION\":{\"idRegion\":\"6\",\"regionName\":\"Trenciansky kraj\",\"idCity\":\"138\",\"cityName\":\"Trencianske Teplice\"},\"STATUS\":{\"isLoged\":true,\"isChating\":false,\"idChat\":0,\"roomName\":\"\",\"lastLogin\":1294925369},\"PROJECT_STATUS\":{\"photoAlbums\":1,\"photoAlbumsFavs\":0,\"videoAlbums\":0,\"videoAlbumsFavs\":0,\"videoAlbumsExts\":0,\"blogPosts\":0,\"emailNew\":0,\"postaNew\":0,\"clubInvitations\":0,\"dashboardItems\":1},\"STATUS_MESSAGE\":{\"statusMessage\":\"\"Status\"\",\"addTime\":\"1294872330\"},\"isFriend\":false,\"isIamFriend\":false}}" Problem is here, json string consist this object: "STATUS_MESSAGE": {"statusMessage":" "some "bad" value" ", "addTime" :"1294872330"} Condition of string which I want modified: string start with "statusMessage":" string can has any *lenght from 0 -N * string end with ", "addTime So I try write pattern for string which start with "statusMessage":", has any lenght and is ended with ", "addTime. Here is it: const string pattern = " \" statusMessage \" : \" .*? \",\"addTime\" "; var regex = new Regex(pattern, RegexOptions.IgnoreCase); //here i would replace " with empty string string result = regex.Replace(jsonString, match => ???); But I think pattern is wrong, also I don’t know how replace apostrophe with empty string (remove apostrophne). My goal is : "statusMessage":" "some "bad" value" to "statusMessage":" "some bad value" Thank for advice

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  • Set fields with instrospection - Problem with String.valueOf(String)

    - by fabb
    Hey there! I'm setting public fields of the Object 'this' via reflection. Both the field name and the value are given as String. I use several various field types: Boolean, Integer, Float, Double, an own enum, and a String. It works with all of them except with a String. The exception that gets thrown is that no method with the Signature String.valueOf(String) exists... Now I use a dirty instanceof workaround to detect if each field is a String and in that case just copy the value to the field. private void setField(String field, String value) throws Exception { Field wField = this.getClass().getField(field); if(wField.get(this) instanceof String){ //TODO dirrrrty hack //stupid workaround as java.lang.String.valueOf(java.lang.String) fails... wField.set(this, value); }else{ Method parseMethod = wField.getType().getMethod("valueOf", new Class[]{String.class}); wField.set(this, parseMethod.invoke(wField, value)); } } Any ideas how to avoid that workaround? Do you think java.lang.String should support the method valueOf(String)? thanks, fabb

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  • Suggestion to reverse string in c#

    - by HasanGursoy
    Is this the right method to reverse a string? I'm planning to use it to reverse a string like: Products » X1 » X3 to X3 « X1 « Products I want it to be a global function which can be used elsewhere. public static string ReverseString(string input, string separator, string outSeparator) { string result = String.Empty; string[] temp = Regex.Split(input, separator, RegexOptions.IgnoreCase); Array.Reverse(temp); for (int i = 0; i < temp.Length; i++) { result += temp[i] + " " + outSeparator + " "; } return result; }

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  • Best practice for string substition with gettext using Python

    - by Malcolm
    Looking for best practice advice on what string substitution technique to use when using gettext(). Or do all techniques apply equally? I can think of at least 3 string techniques: Classic "%" based formatting: "My name is %(name)s" % locals() .format() based formatting: "My name is {name}".format( locals() ) string.Template.safe_substitute() import string template = string.Template( "My name is ${name}" ) template.safe_substitute( locals() ) The advantage of the string.Template technique is that a translated string with with an incorrectly spelled variable reference can still yield a usable string value while the other techniques unconditionally raise an exception. The downside of the string.Template technique appears to be the inability for one to customize how a variable is formatted (padding, justification, width, etc).

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  • Translating C++'s sprintf format string to C#'s string.Format

    - by thebackup
    I found the following C++ code (comments added myself): // frame_name is a char array // prefix is std::string // k is a for loop counter // frames is a std::vector string sprintf(frameName, "%s_%0*s.bmp", prefix.c_str(), k, frames[k].c_str()); I then try to translate it to C# // prefix is string // k is a for loop counter // frames is List<string> string frameName = string.Format("{0}_(what goes in here?).bmp", prefix, k, frames[k]); Basically, what would be the C# equivalent of the C++ format string "%s_%0*s.bmp"?

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  • Trying to convert simple midlet application to Android application but running into problems.

    - by chobo2
    Hi I am trying to do some threading in Android so I took an old threading assignment I had done fora midlet and took out the midlet code and replaced it with android code(such as textview). package com.assignment1; import android.app.Activity; import android.os.Bundle; import android.widget.TextView; public class Threading extends Activity { private TextView tortose; private TextView hare; private Thread hareThread; private Thread torotoseThread; private int num = 0; private int num2 = 0; public Threading() { } /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); tortose = (TextView) findViewById(R.id.TextView01); hare = (TextView) findViewById(R.id.TextView02); Hare newHare = new Hare(); hareThread = new Thread(newHare); hareThread.start(); Torotose newTortose = new Torotose(); torotoseThread = new Thread(newTortose); torotoseThread.start(); //updateDisplay(); } private synchronized void check(int value1, int value2) { if((value1-value2) >= 10) { try { wait(); } catch(Exception ex) { System.out.println(ex); } } } private synchronized void getGoing(int value1, int value2) { if((value1-value2) == 0) { try { notify(); } catch(Exception ex) { System.out.println(ex); } } } private class Hare extends Thread { public void run() { while(true) { num++; hare.setText(Integer.toString(num)); check(num, num2); try { // are threads different in andriod apps? Thread.sleep(100); // hareThread.sleep(100); } catch(Exception ex) { System.out.println(ex); } } } } private class Torotose extends Thread { public void run() { while(true) { num2++; tortose.setText(Integer.toString(num2)); getGoing(num,num2); try { Thread.sleep(200); //torotoseThread.sleep(200); } catch(Exception ex) { System.out.println(ex); } } } } } First it wanted me to change my threads to like static threads.So is this just how Android does it? Next when I run this code it just crashes with some unexpected error. I am not sure what the error is but when I try to debug it and goes to like to create a new "hare" object it shows me this. // Compiled from ClassLoader.java (version 1.5 : 49.0, super bit) public abstract class java.lang.ClassLoader { // Method descriptor #8 ()V // Stack: 3, Locals: 1 protected ClassLoader(); 0 aload_0 [this] 1 invokespecial java.lang.Object() [1] 4 new java.lang.RuntimeException [2] 7 dup 8 ldc <String "Stub!"> [3] 10 invokespecial java.lang.RuntimeException(java.lang.String) [4] 13 athrow Line numbers: [pc: 0, line: 4] Local variable table: [pc: 0, pc: 14] local: this index: 0 type: java.lang.ClassLoader // Method descriptor #14 (Ljava/lang/ClassLoader;)V // Stack: 3, Locals: 2 protected ClassLoader(java.lang.ClassLoader parentLoader); 0 aload_0 [this] 1 invokespecial java.lang.Object() [1] 4 new java.lang.RuntimeException [2] 7 dup 8 ldc <String "Stub!"> [3] 10 invokespecial java.lang.RuntimeException(java.lang.String) [4] 13 athrow Line numbers: [pc: 0, line: 5] Local variable table: [pc: 0, pc: 14] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 14] local: parentLoader index: 1 type: java.lang.ClassLoader // Method descriptor #17 ()Ljava/lang/ClassLoader; // Stack: 3, Locals: 0 public static java.lang.ClassLoader getSystemClassLoader(); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 6] // Method descriptor #19 (Ljava/lang/String;)Ljava/net/URL; // Stack: 3, Locals: 1 public static java.net.URL getSystemResource(java.lang.String resName); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 7] Local variable table: [pc: 0, pc: 10] local: resName index: 0 type: java.lang.String // Method descriptor #23 (Ljava/lang/String;)Ljava/util/Enumeration; // Signature: (Ljava/lang/String;)Ljava/util/Enumeration<Ljava/net/URL;>; // Stack: 3, Locals: 1 public static java.util.Enumeration getSystemResources(java.lang.String resName) throws java.io.IOException; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 8] Local variable table: [pc: 0, pc: 10] local: resName index: 0 type: java.lang.String // Method descriptor #29 (Ljava/lang/String;)Ljava/io/InputStream; // Stack: 3, Locals: 1 public static java.io.InputStream getSystemResourceAsStream(java.lang.String resName); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 9] Local variable table: [pc: 0, pc: 10] local: resName index: 0 type: java.lang.String // Method descriptor #31 ([BII)Ljava/lang/Class; // Signature: ([BII)Ljava/lang/Class<*>; // Stack: 3, Locals: 4 protected final java.lang.Class defineClass(byte[] classRep, int offset, int length) throws java.lang.ClassFormatError; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 10] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: classRep index: 1 type: byte[] [pc: 0, pc: 10] local: offset index: 2 type: int [pc: 0, pc: 10] local: length index: 3 type: int // Method descriptor #39 (Ljava/lang/String;[BII)Ljava/lang/Class; // Signature: (Ljava/lang/String;[BII)Ljava/lang/Class<*>; // Stack: 3, Locals: 5 protected final java.lang.Class defineClass(java.lang.String className, byte[] classRep, int offset, int length) throws java.lang.ClassFormatError; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 11] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: className index: 1 type: java.lang.String [pc: 0, pc: 10] local: classRep index: 2 type: byte[] [pc: 0, pc: 10] local: offset index: 3 type: int [pc: 0, pc: 10] local: length index: 4 type: int // Method descriptor #42 (Ljava/lang/String;[BIILjava/security/ProtectionDomain;)Ljava/lang/Class; // Signature: (Ljava/lang/String;[BIILjava/security/ProtectionDomain;)Ljava/lang/Class<*>; // Stack: 3, Locals: 6 protected final java.lang.Class defineClass(java.lang.String className, byte[] classRep, int offset, int length, java.security.ProtectionDomain protectionDomain) throws java.lang.ClassFormatError; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 12] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: className index: 1 type: java.lang.String [pc: 0, pc: 10] local: classRep index: 2 type: byte[] [pc: 0, pc: 10] local: offset index: 3 type: int [pc: 0, pc: 10] local: length index: 4 type: int [pc: 0, pc: 10] local: protectionDomain index: 5 type: java.security.ProtectionDomain // Method descriptor #46 (Ljava/lang/String;Ljava/nio/ByteBuffer;Ljava/security/ProtectionDomain;)Ljava/lang/Class; // Signature: (Ljava/lang/String;Ljava/nio/ByteBuffer;Ljava/security/ProtectionDomain;)Ljava/lang/Class<*>; // Stack: 3, Locals: 4 protected final java.lang.Class defineClass(java.lang.String name, java.nio.ByteBuffer b, java.security.ProtectionDomain protectionDomain) throws java.lang.ClassFormatError; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 13] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: name index: 1 type: java.lang.String [pc: 0, pc: 10] local: b index: 2 type: java.nio.ByteBuffer [pc: 0, pc: 10] local: protectionDomain index: 3 type: java.security.ProtectionDomain // Method descriptor #52 (Ljava/lang/String;)Ljava/lang/Class; // Signature: (Ljava/lang/String;)Ljava/lang/Class<*>; // Stack: 3, Locals: 2 protected java.lang.Class findClass(java.lang.String className) throws java.lang.ClassNotFoundException; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 14] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: className index: 1 type: java.lang.String // Method descriptor #52 (Ljava/lang/String;)Ljava/lang/Class; // Signature: (Ljava/lang/String;)Ljava/lang/Class<*>; // Stack: 3, Locals: 2 protected final java.lang.Class findLoadedClass(java.lang.String className); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 15] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: className index: 1 type: java.lang.String // Method descriptor #52 (Ljava/lang/String;)Ljava/lang/Class; // Signature: (Ljava/lang/String;)Ljava/lang/Class<*>; // Stack: 3, Locals: 2 protected final java.lang.Class findSystemClass(java.lang.String className) throws java.lang.ClassNotFoundException; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 16] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: className index: 1 type: java.lang.String // Method descriptor #17 ()Ljava/lang/ClassLoader; // Stack: 3, Locals: 1 public final java.lang.ClassLoader getParent(); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 17] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader // Method descriptor #19 (Ljava/lang/String;)Ljava/net/URL; // Stack: 3, Locals: 2 public java.net.URL getResource(java.lang.String resName); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 18] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: resName index: 1 type: java.lang.String // Method descriptor #23 (Ljava/lang/String;)Ljava/util/Enumeration; // Signature: (Ljava/lang/String;)Ljava/util/Enumeration<Ljava/net/URL;>; // Stack: 3, Locals: 2 public java.util.Enumeration getResources(java.lang.String resName) throws java.io.IOException; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 19] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: resName index: 1 type: java.lang.String // Method descriptor #29 (Ljava/lang/String;)Ljava/io/InputStream; // Stack: 3, Locals: 2 public java.io.InputStream getResourceAsStream(java.lang.String resName); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 20] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: resName index: 1 type: java.lang.String // Method descriptor #52 (Ljava/lang/String;)Ljava/lang/Class; // Signature: (Ljava/lang/String;)Ljava/lang/Class<*>; // Stack: 3, Locals: 2 public java.lang.Class loadClass(java.lang.String className) throws java.lang.ClassNotFoundException; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 21] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: className index: 1 type: java.lang.String // Method descriptor #62 (Ljava/lang/String;Z)Ljava/lang/Class; // Signature: (Ljava/lang/String;Z)Ljava/lang/Class<*>; // Stack: 3, Locals: 3 protected java.lang.Class loadClass(java.lang.String className, boolean resolve) throws java.lang.ClassNotFoundException; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 22] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: className index: 1 type: java.lang.String [pc: 0, pc: 10] local: resolve index: 2 type: boolean // Method descriptor #67 (Ljava/lang/Class;)V // Signature: (Ljava/lang/Class<*>;)V // Stack: 3, Locals: 2 protected final void resolveClass(java.lang.Class clazz); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 23] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: clazz index: 1 type: java.lang.Class Local variable type table: [pc: 0, pc: 10] local: clazz index: 1 type: java.lang.Class<?> // Method descriptor #19 (Ljava/lang/String;)Ljava/net/URL; // Stack: 3, Locals: 2 protected java.net.URL findResource(java.lang.String resName); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 24] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: resName index: 1 type: java.lang.String // Method descriptor #23 (Ljava/lang/String;)Ljava/util/Enumeration; // Signature: (Ljava/lang/String;)Ljava/util/Enumeration<Ljava/net/URL;>; // Stack: 3, Locals: 2 protected java.util.Enumeration findResources(java.lang.String resName) throws java.io.IOException; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 25] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: resName index: 1 type: java.lang.String // Method descriptor #76 (Ljava/lang/String;)Ljava/lang/String; // Stack: 3, Locals: 2 protected java.lang.String findLibrary(java.lang.String libName); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 26] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: libName index: 1 type: java.lang.String // Method descriptor #79 (Ljava/lang/String;)Ljava/lang/Package; // Stack: 3, Locals: 2 protected java.lang.Package getPackage(java.lang.String name); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 27] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: name index: 1 type: java.lang.String // Method descriptor #81 ()[Ljava/lang/Package; // Stack: 3, Locals: 1 protected java.lang.Package[] getPackages(); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 28] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader // Method descriptor #83 (Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/net/URL;)Ljava/lang/Package; // Stack: 3, Locals: 9 protected java.lang.Package definePackage(java.lang.String name, java.lang.String specTitle, java.lang.String specVersion, java.lang.String specVendor, java.lang.String implTitle, java.lang.String implVersion, java.lang.String implVendor, java.net.URL sealBase) throws java.lang.IllegalArgumentException; 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 29] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: name index: 1 type: java.lang.String [pc: 0, pc: 10] local: specTitle index: 2 type: java.lang.String [pc: 0, pc: 10] local: specVersion index: 3 type: java.lang.String [pc: 0, pc: 10] local: specVendor index: 4 type: java.lang.String [pc: 0, pc: 10] local: implTitle index: 5 type: java.lang.String [pc: 0, pc: 10] local: implVersion index: 6 type: java.lang.String [pc: 0, pc: 10] local: implVendor index: 7 type: java.lang.String [pc: 0, pc: 10] local: sealBase index: 8 type: java.net.URL // Method descriptor #94 (Ljava/lang/Class;[Ljava/lang/Object;)V // Signature: (Ljava/lang/Class<*>;[Ljava/lang/Object;)V // Stack: 3, Locals: 3 protected final void setSigners(java.lang.Class c, java.lang.Object[] signers); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 30] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: c index: 1 type: java.lang.Class [pc: 0, pc: 10] local: signers index: 2 type: java.lang.Object[] Local variable type table: [pc: 0, pc: 10] local: c index: 1 type: java.lang.Class<?> // Method descriptor #100 (Ljava/lang/String;Z)V // Stack: 3, Locals: 3 public void setClassAssertionStatus(java.lang.String cname, boolean enable); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 31] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: cname index: 1 type: java.lang.String [pc: 0, pc: 10] local: enable index: 2 type: boolean // Method descriptor #100 (Ljava/lang/String;Z)V // Stack: 3, Locals: 3 public void setPackageAssertionStatus(java.lang.String pname, boolean enable); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 32] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: pname index: 1 type: java.lang.String [pc: 0, pc: 10] local: enable index: 2 type: boolean // Method descriptor #106 (Z)V // Stack: 3, Locals: 2 public void setDefaultAssertionStatus(boolean enable); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 33] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader [pc: 0, pc: 10] local: enable index: 1 type: boolean // Method descriptor #8 ()V // Stack: 3, Locals: 1 public void clearAssertionStatus(); 0 new java.lang.RuntimeException [2] 3 dup 4 ldc <String "Stub!"> [3] 6 invokespecial java.lang.RuntimeException(java.lang.String) [4] 9 athrow Line numbers: [pc: 0, line: 34] Local variable table: [pc: 0, pc: 10] local: this index: 0 type: java.lang.ClassLoader } So I am not sure where I went wrong. Thanks

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  • How can I make nested string splits?

    - by Statement
    I have what seemed at first to be a trivial problem but turned out to become something I can't figure out how to easily solve. I need to be able to store lists of items in a string. Then those items in turn can be a list, or some other value that may contain my separator character. I have two different methods that unpack the two different cases but I realized I need to encode the contained value from any separator characters used with string.Split. To illustrate the problem: string[] nested = { "mary;john;carl", "dog;cat;fish", "plainValue" } string list = string.Join(";", nested); string[] unnested = list.Split(';'); // EEK! returns 7 items, expected 3! This would produce a list "mary;john;carl;dog;cat;fish;plainValue", a value I can't split to get the three original nested strings from. Indeed, instead of the three original strings, I'd get 7 strings on split and this approach thus doesn't work at all. What I want is to allow the values in my string to be encoded so I can unpack/split the contents just the way before I packed/join them. I assume I might need to go away from string.Split and string.Join and that is perfectly fine. I might just have overlooked some useful class or method. How can I allow any string values to be packed / unpacked into lists? I prefer neat, simple solutions over bulky if possible. For the curious mind, I am making extensions for PlayerPrefs in Unity3D, and I can only work with ints, floats and strings. Thus I chose strings to be my data carrier. This is why I am making this nested list of strings.

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  • How safe and reliable are C++ String Literals?

    - by DoctorT
    So, I'm wanting to get a better grasp on how string literals in C++ work. I'm mostly concerned with situations where you're assigning the address of a string literal to a pointer, and passing it around. For example: char* advice = "Don't stick your hands in the toaster."; Now lets say I just pass this string around by copying pointers for the duration of the program. Sure, it's probably not a good idea, but I'm curious what would actually be going on behind the scenes. For another example, let's say we make a function that returns a string literal: char* foo() { // function does does stuff return "Yikes!"; // somebody's feeble attempt at an error message } Now lets say this function is called very often, and the string literal is only used about half the time it's called: // situation #1: it's just randomly called without heed to the return value foo(); // situation #2: the returned string is kept and used for who knows how long char* retVal = foo(); In the first situation, what's actually happening? Is the string just created but not used, and never deallocated? In the second situation, is the string going to be maintained as long as the user finds need for it? What happens when it isn't needed anymore... will that memory be freed up then (assuming nothing points to that space anymore)? Don't get me wrong, I'm not planning on using string literals like this. I'm planning on using a container to keep my strings in check (probably std::string). I'm mostly just wanting to know if these situations could cause problems either for memory management or corrupted data.

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  • Interpolation and Morphing of an image in labview and/or openCV

    - by Marc
    I am working on an image manipulation problem. I have an overhead projector that projects onto a screen, and I have a camera that takes pictures of that. I can establish a 1:1 correspondence between a subset of projector coordinates and a subset of camera pixels by projecting dots on the screen and finding the centers of mass of the resulting regions on the camera. I thus have a map proj_x, proj_y <-- cam_x, cam_y for scattered point pairs My original plan was to regularize this map using the Mathscript function griddata. This would work fine in MATLAB, as follows [pgridx, pgridy] = meshgrid(allprojxpts, allprojypts) fitcx = griddata (proj_x, proj_y, cam_x, pgridx, pgridy); fitcy = griddata (proj_x, proj_y, cam_y, pgridx, pgridy); and the reverse for the camera to projector mapping Unfortunately, this code causes Labview to run out of memory on the meshgrid step (the camera is 5 megapixels, which apparently is too much for labview to handle) I then started looking through openCV, and found the cvRemap function. Unfortunately, this function takes as its starting point a regularized pixel-pixel map like the one I was trying to generate above. However, it made me hope that functions for creating such a map might be available in openCV. I couldn't find it in the openCV 1.0 API (I am stuck with 1.0 for legacy reasons), but I was hoping it's there or that someone has an easy trick. So my question is one of the following 1) How can I interpolate from scattered points to a grid in openCV; (i.e., given z = f(x,y) for scattered values of x and y, how to fill an image with f(im_x, im_y) ? 2) How can I perform an image transform that maps image 1 to image 2, given that I know a scattered mapping of points in coordinate system 1 to coordinate system 2. This could be implemented either in Labview or OpenCV. Note: I am tagging this post delaunay, because that's one method of doing a scattered interpolation, but the better tag would be "scattered interpolation"

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