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  • bash-like features in sqlplus, rman and other Oracle command line tools

    - by Gilles Haro
    As far as I can remember, I have always been complaining about the lack of “recall last command” from within sqlplus. Such a basic thing, available in any bash shell or windows cmd terminal, remains missing with Oracle command lines tools. Thanks to davidw who published a post in the french blog EASYTEAM, it is now possible to use a simple rpm package rlwrap to enhance sqlplus, dgmgrl, rman, … tools and give them bash “recall/completion” capabilities. I installed it in a few minutes and I am already wondering how can people work without it. The steps are here : Get the rpm file from sites like RPM PBone. AS root, install the package rpm -ivh rlwrap-0.37-1.el5.x86_64.rpm As Oracle, create a dictionnary file (for autocompletion) . This file is made of a series of words to be used for autocompletion. Put in it the list of dictionary tables, the list of sql commands, the list of sqlplus commands… whatever your like. And use the <tab> key as you would in a bash shell. $HOME/.oracle_keywords Create an alias for sqlplus alias sqlplus='/usr/bin/rlwrap -if $HOME/.oracle_keywords $ORACLE_HOME/bin/sqlplus' And enjoy it !!! Thank you DavidW. Gilles Haro Technical Expert - Core Technology, Oracle Consulting  Technorati Tags: rlwrap bash sqlplus

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  • whats the name of this pattern?

    - by Wes
    I see this a lot in frameworks. You have a master class which other classes register with. The master class then decides which of the registered classes to delegate the request to. An example based passed in class may be something this. public interface Processor { public boolean canHandle(Object objectToHandle); public void handle(Object objectToHandle); } public class EvenNumberProcessor extends Processor { public boolean canHandle(Object objectToHandle) { if (!isNumeric(objectToHandle)){ return false } return isEven(objectToHandle); } public void handle(objectToHandle) { //Optionally call canHandleAgain to ensure the calling class is fufilling its contract doSomething(); } } public class OddNumberProcessor extends Processor { public boolean canHandle(Object objectToHandle) { if (!isNumeric(objectToHandle)){ return false } return isOdd(objectToHandle); } public void handle(objectToHandle) { //Optionally call canHandleAgain to ensure the calling class is fufilling its contract doSomething(); } } //Can optionally implement processor interface public class processorDelegator { private List processors; public void addProcessor(Processor processor) { processors.add(processor); } public void process(Object objectToProcess) { //Lookup relevant processor either by keeping a list of what they can process //Or query each one to see if it can process the object. chosenProcessor=chooseProcessor(objectToProcess); chosenProcessor.handle(objectToProcess); } } Note there are a few variations I see on this. In one variation the sub classes provide a list of things they can process which the ProcessorDelegator understands. The other variation which is listed above in fake code is where each is queried in turn. This is similar to chain of command but I don't think its the same as chain of command means that the processor needs to pass to other processors. The other variation is where the ProcessorDelegator itself implements the interface which means you can get trees of ProcessorDelegators which specialise further. In the above example you could have a numeric processor delegator which delegates to an even/odd processor and a string processordelegator which delegates to different strings. My question is does this pattern have a name.

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  • Any algorithm to dedicate a set of known resources to a set of known requirements (scheduling)

    - by Saeed Neamati
    I'm developing an application to help school principals in dedicating teachers to classes and courses over the hours of a week (scheduling). The scenario is roughly something like this: User enters the list of teachers and their free times into the system User enters the list of courses for this semester User enters the list of available classes into the system Well, up to here, there is no big deal. Just simple CRUD operations and nothing extraordinary. However, now what makes this system useful is that the application should automatically and based on an algorithm create the semester scheduling. I think you've got the main idea here. For example application should suggest that teacher A should go to class 1 for mathematics, and at the same time teacher B should go to class 2 for physics. This way all of the classes would be dedicated to lessons and teacher times won't overlap each other. Piece a cake for school principal. However, I can't find a good algorithm for this resource dedication. I mean it seems hard to me. Searching Google resulted in articles from different websites, but they are of no help and use to me. For example: http://en.wikipedia.org/wiki/Resource_allocation or http://en.wikipedia.org/wiki/Scheduling_(production_processes) Is there any algorithm out there, or any application or engine which can help me here? Does this requirements have a known name, like for example time scheduling engine? Any help would be appreciated.

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  • How to market R at your institute?

    - by ran2
    Okay, I admit there are lots of threads R vs. something. The strengths of R are obvious to most people here. Still though advertising R in an environment that has been preferring various kinds of other software for quite some time is not easy. Moreover, even in the limited time I´ve been dealing with R, it improved so dramatically that I would mention things among its strengths that I would not have listed when I started my personal R-evolution. So, what I am trying to do here is to collect the most recent and striking arguments that can be put in nutshell and be presented easily. What I got on my list so far is: the Springer useR series ggplot2 and its documentation open source CRAN Rapache rcpp rsocket What can you add to this list? SO threads are also very welcome as answers. EDIT: so far, though indeed very helpful, most answers are arguments (pros) why one would want to use R. Do you have some specific hints that I could include in some kind of overview presentation? EDIT2: I wanted to add this link about R's future to the list...

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  • Are DDD Aggregates really a good idea in a Web Application?

    - by Mystere Man
    I'm diving in to Domain Driven Design and some of the concepts i'm coming across make a lot of sense on the surface, but when I think about them more I have to wonder if that's really a good idea. The concept of Aggregates, for instance makes sense. You create small domains of ownership so that you don't have to deal with the entire domain model. However, when I think about this in the context of a web app, we're frequently hitting the database to pull back small subsets of data. For instance, a page may only list the number of orders, with links to click on to open the order and see its order id's. If i'm understanding Aggregates right, I would typically use the repository pattern to return an OrderAggregate that would contain the members GetAll, GetByID, Delete, and Save. Ok, that sounds good. But... If I call GetAll to list all my order's, it would seem to me that this pattern would require the entire list of aggregate information to be returned, complete orders, order lines, etc... When I only need a small subset of that information (just header information). Am I missing something? Or is there some level of optimization you would use here? I can't imagine that anyone would advocate returning entire aggregates of information when you don't need it. Certainly, one could create methods on your repository like GetOrderHeaders, but that seems to defeat the purpose of using a pattern like repository in the first place. Can anyone clarify this for me?

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  • Places to store basic data

    - by Ella
    I am using PHP. I'm building a fully modular CMS, which is destined for the public. Some people might view this as a framework, but I intend to write a set of extensions for it, extensions that will make it a CMS :P Because it's completely modular I have a problem figuring out how to load extensions. Practically I need to get the list of active extensions, so I can load them inside my base class. I load them by reading some file headers, which contain a "dependency" field. That field decides the order in which I have to instantiate the objects. The problem is that when the CMS starts I have no database interface, because that's an extension too, so I can't store the active extensions list in the database :) You might ask how are extensions activated in the first place. Well - in the administration interface, which is an extension as well (obviously on first install of the CMS there will be some extensions active by default). Could writing that list inside a text file be a solution? The problem is that a lot of hosts are not very nice with scripts when they write files. And since this CMS is public I might have a problem here?

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  • How do I keep a 3D model on the screen in OpenGL?

    - by NoobScratcher
    I'm trying to keep a 3D model on the screen by placing my glDrawElement functions inside the draw function with the declarations at the top of .cpp. When I render the model, the model attaches it self to the current vertex buffer object. This is because my whole graphical user interface is in 2D quads except the window frame. Is there a way to avoid this from happening? or any common causes of this? Creating the file object: int index = IndexAssigner(1, 1); //make a fileobject and store list and the index of that list in a c string ifstream file (list[index].c_str() ); //Make another string //string line; points.push_back(Point()); Point p; int face[4]; Model rendering code: int numfloats = 4; float* point=reinterpret_cast<float*>(&points[0]); int num_bytes=numfloats*sizeof(float); cout << "Size Of Point" << sizeof(Point) << endl; GLuint vertexbuffer; glGenVertexArrays(1, &vao[3]); glGenBuffers(1, &vertexbuffer); glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer); glBufferData(GL_ARRAY_BUFFER, points.size()*sizeof(points), points.data(), GL_STATIC_DRAW); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, num_bytes, &points[0]); glEnableClientState(GL_VERTEX_ARRAY); glVertexPointer(3, GL_FLOAT, points.size(), &points[0]); glEnableClientState(GL_INDEX_ARRAY); glIndexPointer(GL_FLOAT, faces.size(), faces.data()); glEnableVertexAttribArray(0); glDrawElements(GL_QUADS, points.size(), GL_UNSIGNED_INT, points.data()); glDrawElements(GL_QUADS, faces.size(), GL_UNSIGNED_INT, faces.data());

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  • Approach to retrieve files from server

    - by Aerus
    I'm in the process of making a Java application with a corresponding update application. At any given time the user may want to update the application and the updater will ask for a list of files of the latest release. Based on this list, the updater can determine which files need to be downloaded to complete the update. I now have 2 approaches to solve this, but i would like to know what approach will put the least stress on my application and server. I could send a list of files i want to download to my server and the server zips the files and simply returns this compressed file to the application. The updater sents a request for each seperate file to the server, which simply returns the file The application will be used mainly in Belgium and The Netherlands and connections/bandwidth tend to be pretty decent in here. The average size of a single file should be around 100Kb and at most 1Mb. I expect an update to have anywhere between 10 to 50 new files. I expect at most 100 persons/day to update the application, i.e. in the week when a new version is released. I hope this is enough information to sketch my problem and any advice is welcome. If there is another common way to tackle this, i'd be glad to hear it.

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  • Performing a Depth First Search iteratively using async/parallel processing?

    - by Prabhu
    Here is a method that does a DFS search and returns a list of all items given a top level item id. How could I modify this to take advantage of parallel processing? Currently, the call to get the sub items is made one by one for each item in the stack. It would be nice if I could get the sub items for multiple items in the stack at the same time, and populate my return list faster. How could I do this (either using async/await or TPL, or anything else) in a thread safe manner? private async Task<IList<Item>> GetItemsAsync(string topItemId) { var items = new List<Item>(); var topItem = await GetItemAsync(topItemId); Stack<Item> stack = new Stack<Item>(); stack.Push(topItem); while (stack.Count > 0) { var item = stack.Pop(); items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } } return items; } I was thinking of something along these lines, but it's not coming together: var tasks = stack.Select(async item => { items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } }).ToList(); if (tasks.Any()) await Task.WhenAll(tasks); The language I'm using is C#.

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  • Design Pattern for Skipping Steps in a Wizard

    - by Eric J.
    I'm designing a flexible Wizard system that presents a number of screens to complete a task. Some screens may need to be skipped based on answers to prompts on one or more previous screens. The conditions to skip a given screen need to be editable by a non-technical user via a UI. Multiple conditions need only be combined with and. I have an initial design in mind, but it feels inelegant. I wonder if there's a better way to approach this class of problem. Initial Design UI where The first column allows the user to select a question from a previous screen. The second column allows the user to select an operator applicable to the type of question asked. The third column allows the user to enter one or more values depending on the selected operator. Object Model public enum Operations { ... } public class Condition { int QuestionId { get; set; } Operations Operation { get; set; } List<object> Parameters { get; private set; } } List<Condition> pageSkipConditions; Controller Logic bool allConditionsTrue = pageSkipConditions.Count > 0; foreach (Condition c in pageSkipConditions) { allConditionsTrue &= Evaluate(previousAnswers, c); } // ... private bool Evaluate(List<Answers> previousAnswers, Condition c) { switch (c.Operation) { case Operations.StartsWith: // logic for this operation // etc. } }

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  • Loading Entities Dynamically with Entity Framework

    - by Ricardo Peres
    Sometimes we may be faced with the need to load entities dynamically, that is, knowing their Type and the value(s) for the property(ies) representing the primary key. One way to achieve this is by using the following extension methods for ObjectContext (which can be obtained from a DbContext, of course): 1: public static class ObjectContextExtensions 2: { 3: public static Object Load(this ObjectContext ctx, Type type, params Object [] ids) 4: { 5: Object p = null; 6:  7: EntityType ospaceType = ctx.MetadataWorkspace.GetItems<EntityType>(DataSpace.OSpace).SingleOrDefault(x => x.FullName == type.FullName); 8:  9: List<String> idProperties = ospaceType.KeyMembers.Select(k => k.Name).ToList(); 10:  11: List<EntityKeyMember> members = new List<EntityKeyMember>(); 12:  13: EntitySetBase collection = ctx.MetadataWorkspace.GetEntityContainer(ctx.DefaultContainerName, DataSpace.CSpace).BaseEntitySets.Where(x => x.ElementType.FullName == type.FullName).Single(); 14:  15: for (Int32 i = 0; i < ids.Length; ++i) 16: { 17: members.Add(new EntityKeyMember(idProperties[i], ids[i])); 18: } 19:  20: EntityKey key = new EntityKey(String.Concat(ctx.DefaultContainerName, ".", collection.Name), members); 21:  22: if (ctx.TryGetObjectByKey(key, out p) == true) 23: { 24: return (p); 25: } 26:  27: return (p); 28: } 29:  30: public static T Load<T>(this ObjectContext ctx, params Object[] ids) 31: { 32: return ((T)Load(ctx, typeof(T), ids)); 33: } 34: } This will work with both single-property primary keys or with multiple, but you will have to supply each of the corresponding values in the appropriate order. Hope you find this useful!

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  • I don't understand why one of my vbo is overwritten by another

    - by Alays
    to create a vbo I use this function: public void loadVBO(){ vboID = GL15.glGenBuffers(); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vboID); GL15.glBufferData(GL15.GL_ARRAY_BUFFER, buf, GL15.GL_STATIC_DRAW); // Put the position coordinates in attribute list 0 GL20.glVertexAttribPointer(0, 4, GL11.GL_FLOAT, false,4*4+4*4+4*4+2*4 , 0); // Put the color components in attribute list 1 GL20.glVertexAttribPointer(1, 4, GL11.GL_FLOAT, false,4*4+4*4+4*4+2*4 , 4*4); GL20.glVertexAttribPointer(2, 4, GL11.GL_FLOAT, false,4*4+4*4+4*4+2*4 , 4*4+4*4); // Put the texture coordinates in attribute list 2 GL20.glVertexAttribPointer(3, 4, GL11.GL_FLOAT, false,4*4+4*4+4*4+2*4 , 4*4+4*4+4*4); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0); } to display a vbo I use this function: public void displayVBO(){ GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, vboID); GL20.glEnableVertexAttribArray(0); GL20.glEnableVertexAttribArray(1); GL20.glEnableVertexAttribArray(2); GL20.glEnableVertexAttribArray(3); GL11.glDrawArrays(GL_TRIANGLES, 0, buf.capacity()); GL20.glDisableVertexAttribArray(0); GL20.glDisableVertexAttribArray(1); GL20.glDisableVertexAttribArray(2); GL20.glDisableVertexAttribArray(3); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0); } So when I call map.loadVBO() and then ocean.loadVBO(), I think the second call overwrite the first vbo I don't know how ... When I call map.display() and ocean.display(), I have the ocean draw 2 times .... Thanks.

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  • Neural network input preprocessing

    - by TND
    It's clear that the effectiveness of a neural network depends strongly on the format you give it to work with. You want to preprocess it into the most convenient form you can algorithmically get to, so that the neural network doesn't have to account for that itself. I'm working on a little project that (surprise!) is going to be using neural networks. My future goal is to eventually use NEAT, which I'm really excited about. Anyway, one of my ideas involves moving entities in continuous 2D space, from a top-down perspective (this would be a really cool game AI). Of course, unless these guys are blind, they're going to be able to see the world around them. There's a lot of different ways this information could be fed into the network. One interesting but expensive way is to simply render a top-down "view" of things, with the entities as dots on the picture, and feed that in. I was hoping for something much simpler to use (at least at first), such as a list of the x (maybe 7 or so) nearest entities and their position in relative polar coordinates, orientation, health, etc., but I'm trying to think of the best way to do it. My first instinct was to order them by distance, which would inherently also train the neural network to consider those more "important". However, I was thinking- what if there's two entities that are nearly the same distance away? They could easily alternate indexes in that list, confusing the network. My question is, is there a better way of representing this? Essentially, the issue is the network needs a good way of keeping track of who's who, while knowing (by being inputted) relevant information about the list of entities it can see. Thanks!

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  • Conventions for search result scoring

    - by DeaconDesperado
    I assume this type of question is more on-topic here than on regular SO. I have been working on a search feature for my team's web application and have had a lot of success building a multithreaded, "divide and conquer" processing system to work through a large amount of fulltext. Our problem domain is pretty specific. Users of the app generate posts, and as a general rule, posts that are more recent are considered to be of greater relevance. Some of the data we are trying to extract from search is very specific (user's feelings about specific items or things) and we are using python nltk to do named-entity extraction to find interesting likely query terms. Essentially we look for descriptive adjective-noun pairs and generate a general picture of a user's expressed sentiment as a list of tokens. This search is intended as an internal tool for our team to draw out a local picture of sentiments like "soggy pizza." There's some machine learning in there too to do entity resolution on terms like "soggy" to all manner of adjectives expressing nastiness. My problem is I am at a loss for how to go about scoring these results. The text being searched is split up into tokens in a list, so my initial approach would be to normalize a float score between 0.0-1.0 generated off of how far into the list the terms appear and how often they are repeated (a later mention of the term being worth less, earlier more, greater frequency-greater score, etc.) A certain amount of weight could be given to the timestamp as well, though I am not certain how to calculate this. I am curious if anyone has had to solve a similar problem in a search relevance grading between appreciable metrics (frequency, term location/colocation, recency) and if there are and guidelines for how to weight each. I should mention as well that the final fallback procedure in the search is to pipe the query to Sphinx, which has its own scoring practices. Sphinx operates as the last resort in case our application specific processing can't find any eligible candidates.

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  • Points around a circumference C#

    - by Lautaro
    Im trying to get a list of vectors that go around a circle, but i keep getting the circle to go around several times. I want one circel and the dots to be placed along its circumference. I want the first dot to start at 0 and the last dot to end just before 360. Also i need to be able to calculate the spacing by the ammount of points. List<Vector2> pointsInPath = new List<Vector2>(); private int ammountOfPoints = 5; private int blobbSize = 200; private Vector2 topLeft = new Vector2(100, 100); private Vector2 blobbCenter; private int endAngle = 50; private int angleIncrementation; public Blobb() { blobbCenter = new Vector2(blobbSize / 2, blobbSize / 2) + topLeft; angleIncrementation = endAngle / ammountOfPoints; for (int i = 0; i < ammountOfPoints; i++) { pointsInPath.Add(getPointByAngle(i * angleIncrementation, 100, blobbCenter)); // pointsInPath.Add(getPointByAngle(i * angleIncrementation, blobbSize / 2, blobbCenter)); } } private Vector2 getPointByAngle(float angle, float distance, Vector2 centre) { return new Vector2((float)(distance * Math.Cos(angle) ), (float)(distance * Math.Sin(angle))) + centre ; }

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  • BoundingSpheres move when they should not

    - by NDraskovic
    I have a XNA 4.0 project in which I load a file that contains type and coordinates of items I need to draw to the screen. Also I need to check if one particular type (the only movable one) is passing in front or trough other items. This is the code I use to load the configuration: if (ks.IsKeyDown(Microsoft.Xna.Framework.Input.Keys.L)) { this.GraphicsDevice.Clear(Color.CornflowerBlue); Otvaranje.ShowDialog(); try { using (StreamReader sr = new StreamReader(Otvaranje.FileName)) { String linija; while ((linija = sr.ReadLine()) != null) { red = linija.Split(','); model = red[0]; x = red[1]; y = red[2]; z = red[3]; elementi.Add(Convert.ToInt32(model)); podatci.Add(new Vector3(Convert.ToSingle(x), Convert.ToSingle(y), Convert.ToSingle(z))); sfere.Add(new BoundingSphere(new Vector3(Convert.ToSingle(x), Convert.ToSingle(y), Convert.ToSingle(z)), 1f)); } } } catch (Exception ex) { Window.Title = ex.ToString(); } } The "Otvaranje" is an OpenFileDialog object, "elementi" is a List (determines the type of item that would be drawn), podatci is a List (determines the location where the items will be drawn) and sfere is a List. Now I solved the picking algorithm (checking for ray and bounding sphere intersection) and it works fine, but the collision detection does not. I noticed, while using picking, that BoundingSphere's move even though the objects that they correspond to do not. The movable object is drawn to the world1 Matrix, and the static objects are drawn into the world2 Matrix (world1 and world2 have the same values, I just separated them so that the static elements would not move when the movable one does). The problem is that when I move the item I want, all boundingSpheres move accordingly. How can I move only the boundingSphere that corresponds to that particular item, and leave the rest where they are?

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  • Can't change folder background

    - by newcomer
    I tried to change via dragging from the Backgrounds and Emblems window, but the icon just goes back to that window rather than changing the folder background.However, I can change the task bar by this drag-n-drop. Probably it is something about changing ownership permission? if so how to change that? In /home/mashruf/.gconf/apps/nautilus/preferences/%gconf.xml file it says:, Should I change this file? how? <?xml version="1.0"?> <gconf> <entry name="click_policy" mtime="1297597800" type="string"> <stringvalue>single</stringvalue> </entry> <entry name="default_folder_viewer" mtime="1297597336" type="string"> <stringvalue>list_view</stringvalue> </entry> <entry name="media_autorun_x_content_open_folder" mtime="1297534321" type="list" ltype="string"> </entry> <entry name="media_autorun_x_content_ignore" mtime="1297534321" type="list" ltype="string"> </entry> <entry name="media_autorun_x_content_start_app" mtime="1297534321" type="list" ltype="string"> <li type="string"> <stringvalue>x-content/software</stringvalue> </li> </entry> <entry name="start_with_location_bar" mtime="1297300028" type="bool" value="true"/> <entry name="side_pane_view" mtime="1297269334" type="string"> <stringvalue>NautilusTreeSidebar</stringvalue> </entry> <entry name="navigation_window_saved_maximized" mtime="1297600306" type="bool" value="false"/> <entry name="navigation_window_saved_geometry" mtime="1297600306" type="string"> <stringvalue>964x608+59+2</stringvalue> </entry> <entry name="sidebar_width" mtime="1297390418" type="int" value="192"/> </gconf>

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  • C# find a value from an object column using a string from another column

    - by Graham
    I have 2 list in foreach loops.. I currently use a 'switch' statement on the m.columnname and then assign the value of that column to another var map as per below.. If m.columnname = 'DocHeading' then v.docheading is assigned to map.value.. There will always be a match on m.columnname to a column in the var v. is there a way to get the value from the var v using the string from m.columnname? The reason is that the users will want to add and change column names and I dont want to have to change this code all the time.. Hope this makes sense List spreadMapping = new List(); foreach (var m in mappings) { foreach (var v in hvalues) { SpreadMappings map = new SpreadMappings(); switch (m.ColumnName) { case “DocHeading”: map.ColumnX = m.ColumnX; map.ColumnY = m.ColumnY; map.ColumnValue = v.DocHeading; map.ColumnName = m.ColumnName; map.ColumnId = v.Id; map.ColumnSheetName = sheetName; spreadMapping.Add(map); break;

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  • Randomly and uniquely iterating over a range

    - by Synetech
    Say you have a range of values (or anything else) and you want to iterate over the range and stop at some indeterminate point. Because the stopping value could be anywhere in the range, iterating sequentially is no good because it causes the early values to be accessed more often than later values (which is bad for things that wear out), and also because it reduces performance since it must traverse extra values. Randomly iterating is better because it will (on average) increase the hit-rate so that fewer values have to be accessed before finding the right one, and also distribute the accesses more evenly (again, on average). The problem is that the standard method of randomly jumping around will result in values being accessed multiple times, and has no automatic way of determining when each value has been checked and thus the whole range has been exhausted. One simplified and contrived solution could be to make a list of each value, pick one at random, then remove it. Each time through the loop, you pick one fromt he set of remaining items. Unfortunately this only works for small lists. As a (forced) example, say you are creating a game where the program tries to guess what number you picked and shows how many guess it took. The range is between 0-255 and instead of asking Is it 0? Is it 1? Is it 2?…, you have it guess randomly. You could create a list of 255 numbers, pick randomly and remove it. But what if the range was between 0-232? You can’t really create a 4-billion item list. I’ve seen a couple of implementations RNGs that are supposed to provide a uniform distribution, but none that area also supposed to be unique, i.e., no repeated values. So is there a practical way to randomly, and uniquely iterate over a range?

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  • snapping an angle to the closest cardinal direction

    - by Josh E
    I'm developing a 2D sprite-based game, and I'm finding that I'm having trouble with making the sprites rotate correctly. In a nutshell, I've got spritesheets for each of 5 directions (the other 3 come from just flipping the sprite horizontally), and I need to clamp the velocity/rotation of the sprite to one of those directions. My sprite class has a pre-computed list of radians corresponding to the cardinal directions like this: protected readonly List<float> CardinalDirections = new List<float> { MathHelper.PiOver4, MathHelper.PiOver2, MathHelper.PiOver2 + MathHelper.PiOver4, MathHelper.Pi, -MathHelper.PiOver4, -MathHelper.PiOver2, -MathHelper.PiOver2 + -MathHelper.PiOver4, -MathHelper.Pi, }; Here's the positional update code: if (velocity == Vector2.Zero) return; var rot = ((float)Math.Atan2(velocity.Y, velocity.X)); TurretRotation = SnapPositionToGrid(rot); var snappedX = (float)Math.Cos(TurretRotation); var snappedY = (float)Math.Sin(TurretRotation); var rotVector = new Vector2(snappedX, snappedY); velocity *= rotVector; //...snip private float SnapPositionToGrid(float rotationToSnap) { if (rotationToSnap == 0) return 0.0f; var targetRotation = CardinalDirections.First(x => (x - rotationToSnap >= -0.01 && x - rotationToSnap <= 0.01)); return (float)Math.Round(targetRotation, 3); } What am I doing wrong here? I know that the SnapPositionToGrid method is far from what it needs to be - the .First(..) call is on purpose so that it throws on no match, but I have no idea how I would go about accomplishing this, and unfortunately, Google hasn't helped too much either. Am I thinking about this the wrong way, or is the answer staring at me in the face?

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  • Implementing my Entity System. Questions about some problems I have found.

    - by Notbad
    Hi!, Well during this week I have deciding about implementation of my entity system. It is a big topic so it has been difficult to take one option from the whole. This has been my decision: 1) I don't have an entity class it is just an id. 2) I have systems that contain a list of components (the list is homegenous, I mean, RenderSystem will just have RenderComponents). 3) Compones will be just data. 4) There would be some kind of "entity prototypes" in a manager or something from we will create entity instances.Ideally they will define the type of components it has and initialization data. 5) Prototype code to create an entity (this is from the top of my head): int id=World::getInstance()->createEntity("entity template"); 6) This will notify all systems that a new entity has been created, and if the entity needs a component that the system handles it will add it to the entity. Ok, this are the ideas. Let's see if some can help with the problems: 1) The main problem is this templates that are sent to the systems in creation process to populate the entity with needed components. What would you use, an OR(ed) int?, a list of strings?. 2) How to do initialization for components when the entity has been created? How to store this in the template? I have thought about having a function in the template that is virtual and after entity is created an populated, gets the components and sets initialization values. 3) Don't you think this is a lot of work for just an entity creation?. Sorry for the long post, I have tried to expose my ideas and finding in order other could have a start beside exposing my problems. Thanks in advance, Notbad.

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  • More efficient in range checking

    - by Mob
    I am going to use a specific example in my question, but overall it is pretty general. I use java and libgdx. I have a ship that moves through space. In space there is debris that the ship can tractor beam in and and harvest. Debris is stored in a list, and the object contains it own x and y values. So currently there is no way to to find the debris's location without first looking at the debris object. Now at any given time there can be a huge (1000+) amount of debris in space, and I figure that calculating the distance between the ship and every single piece of debris and comparing it to maximum tractor beam length is rather inefficient. I have thought of dividing space into sectors, and have each sector contain a list of every object in it. This way I could only check nearby sectors. However this essentially doubles memory for the list. (I would reference the same object so it wouldn't double overall. I am not CS major, but I doubt this would be hugely significant.) This also means anytime an object moves it has to calculate which sector it is in, again not a huge problem. I also don't know if I can use some sort of 2D MAP that uses x and y values as keys. But since I am using float locations this sounds more trouble than its worth. I am kind of new to programming games, and I imagined there would be some eloquent solution to this issue.

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  • Find possible variations of one item out of multiple baskets.

    - by tugberk
    I have three baskets of balls and each of them has 10 balls which have the following numbers: Basket 1: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 Basket 2: 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 Basket 3: 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 What would be the possible variations If I were to pick one ball from each basket? I guess this is called as Probability in Mathematics but not sure. How would you write this code in C# (or any other programming language) to get the correct results? Edit: Based on @Kilian Foth's comment, here is the solution in C#: class Program { static void Main(string[] args) { IEnumerable<string> basket1 = new List<string> { "1", "2", "3", "4", "5", "6", "7", "8", "9", "10" }; IEnumerable<string> basket2 = new List<string> { "11", "12", "13", "14", "15", "16", "17", "18", "19", "20" }; IEnumerable<string> basket3 = new List<string> { "21", "22", "23", "24", "25", "26", "27", "28", "29", "30" }; foreach (var item1 in basket1) foreach (var item2 in basket2) foreach (var item3 in basket3) { Console.WriteLine("{0}, {1}, {2}", item1, item2, item3); } Console.ReadLine(); } }

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  • Is There a Cloud Over OpenWorld?

    - by Tony Berk
    If you have been to OpenWorld in the past, you know it can be overwhelming or at least a bit "large." If this is your first time at OpenWorld, get ready! You are in for a big (or I should say HUGE) treat. The first thing you'll notice when you get to San Francisco is there are a lot of people, buses with "Oracle" posters, large exhibit halls filled with demos, games and tchotchkes from vendors with hot new solutions, and then there are the sessions. Yes, in fact there are over 2000 sessions. How can you possibly sort through 2000 sessions to find the best 20 or so for you? Which are the 1% for you? We will try to help with some insight over the next few weeks.  I'm going start at the highest level. Up in the Clouds! Since I know many people are looking for an update on The Oracle Cloud. We will drill down into the cloud and other topics for CRM and Customer Experience sessions in the next set of posts. Below is a list of some of the Oracle executive keynotes during OpenWorld highlighting The Oracle Cloud and applications related topics (the full list is here). In these sessions you will get details on Oracle's strategy and how Oracle is changing the industry to help our customers be more efficient, effective and innovative. Sunday, September 30 6:00pm - 7:00pm Larry Ellison: Hardware and Software, Engineered to Work Together: Why it's a Different Approach Tuesday, October 2 8:45am - 9:45am Thomas Kurian: The Oracle Cloud: Oracle's Cloud Platform and Application's Strategy Tuesday, October 2 3:30pm - 4:30pm Larry Ellison: The Oracle Cloud: Where Social is Built in Thursday, October 4 9:45am - 10:45am Mark Hurd: See More, Act Faster: Oracle Business Analytics We encourage you to also join the keynotes on the Oracle Database and Cloud Infrastructure and the fascinating partner keynotes, as well. Check the full list on the OpenWorld site. Oh, if you haven't registered yet, what are you waiting for? OpenWorld Registration Details.

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  • Advanced Experiments with JavaScript, CSS, HTML, JavaFX, and Java

    - by Geertjan
    Once you're embedding JavaScript, CSS, and HTML into your Java desktop application, via the JavaFX browser, a whole range of new possibilities open up to you. For example, here's an impressive page on-line, notice that you can drag items and drop them in new places: http://nettuts.s3.amazonaws.com/127_iNETTUTS/demo/index.html The source code of the above is provided too, so you can drop the various files directly into your NetBeans module and use the JavaFX WebEngine to load the HTML page into the JavaFX browser. Once the JavaFX browser is in a NetBeans TopComponent, you'll have the start of an off-line news composer, something like this: WebView view = new WebView(); view.setMinSize(widthDouble, heightDouble); view.setPrefSize(widthDouble, heightDouble); webengine = view.getEngine(); URL url = getClass().getResource("index.html"); webengine.load(url.toExternalForm()); webengine.getLoadWorker().stateProperty().addListener( new ChangeListener() { @Override public void changed(ObservableValue ov, State oldState, State newState) { if (newState == State.SUCCEEDED) { Document document = (Document) webengine.executeScript("document"); NodeList list = document.getElementById("columns").getChildNodes(); for (int i = 0; i < list.getLength(); i++) { EventTarget et = (EventTarget) list.item(i); et.addEventListener("click", new EventListener() { @Override public void handleEvent(Event evt) { instanceContent.add(new Date()); } }, true); } } } }); The above is the code showing how, whenever a news item is clicked, the current date can be published into the Lookup. As you can see, I have a viewer component listening to the Lookup for dates.

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