Search Results

Search found 15637 results on 626 pages for 'memory efficient'.

Page 514/626 | < Previous Page | 510 511 512 513 514 515 516 517 518 519 520 521  | Next Page >

  • C# Type conversion between two similar Datatable objects

    - by Ali
    I have .NET project with sync framework and two separate Datasets for MS SQL and Compact SQL. in my base class I have a generic DataTable object. in my derived classed I assign Typed DataTable to the generic object based on whether the application is operating online or offline: example: if (online) _dataTable = new MSSQLDataSet.Customer; else _dataTable = new CompactSQLDataSet.Customer; Now every where in my code i have to check and do a cast based on the current network mode like this: public void changeCustomerID(int ID) { if (online) (MSSQLDataSet.CustomerDataTable)_dataTable)[i].CustomerID = value; else (CompactMSSQLDataSet.CustomerDataTable)_dataTable)[i].CustomerID = value; } but I don't think this is very efficient and I believe it can be done in a smarter way to only use one line of code by dynamically getting the Type of _dataTable on the run time. my problem is at the design time, in order to acess datatable porperties such as "CustomerID" it has to be casted to either MSSQLDataSet.CustomerDataTable or CompactMSSQLDataSet.CustomerDataTable. Is there a way to have a function or a operator to convert the _datatable to its runtime type but still be able to use it's design time properties which are the same between the two types? something like: ((aType)_dataTable)[i].CustomerID = value; //or GetRuntimeType(_dataTable)[i].CustomerID = value;

    Read the article

  • How do I detect proximity of the mouse pointer to a line in Flex?

    - by Hanno Fietz
    I'm working on a charting UI in Flex. One of the features I want to implement is "snapping" of the mousepointer to the data points in the diagram. I. e., if the user hovers the mouse pointer over a line diagram and gets close to the data point, I want the pointer to move to the exact coordinates and show a marker, like this: Currently, the lines are drawn on a Shape, using the Graphics API. The Shape is a child DisplayObject of a custom UIComponent subclass with the exact same dimensions. This means, I already get mouseOver events on the parent of the diagram's canvas. Now I need a way to detect if the pointer is close to one of the data points. I. e. I need an answer to the question "Which data points lie within a radius of x pixels from my current position and which of them is closest?" upon each move of the mouse. I can think of the following possibilities: draw the lines not as simple lines in the graphics API, but as more advanced objects that can have their own mouseOver events. However, I want the snapping to trigger before the mouse is actually over the line. check the original data for possible candidates upon each mouse movement. Using binary search, I might be able to reduce the number of items I have to compare sufficently. prepare some kind of new data structure from the raw data that makes the above search more efficient. I don't know how that would look like. I'm guessing this is a pretty standard problem for a number of applications, but probably the actual code usually is inside of some framework. Is there anything I can read about this topic?

    Read the article

  • N-gram split function for string similarity comparison

    - by Michael
    As part of excersise to better understand F# which I am currently learning , I wrote function to split given string into n-grams. 1) I would like to receive feedback about my function : can this be written simpler or in more efficient way? 2) My overall goal is to write function that returns string similarity (on 0.0 .. 1.0 scale) based on n-gram similarity; Does this approach works well for short strings comparisons , or can this method reliably be used to compare large strings (like articles for example). 3) I am aware of the fact that n-gram comparisons ignore context of two strings. What method would you suggest to accomplish my goal? //s:string - target string to split into n-grams //n:int - n-gram size to split string into let ngram_split (s:string, n:int) = let ngram_count = s.Length - (s.Length % n) let ngram_list = List.init ngram_count (fun i -> if( i + n >= s.Length ) then s.Substring(i,s.Length - i) + String.init ((i + n) - s.Length) (fun i -> "#") else s.Substring(i,n) ) let ngram_array_unique = ngram_list |> Seq.ofList |> Seq.distinct |> Array.ofSeq //produce tuples of ngrams (ngram string,how much occurrences in original string) Seq.init ngram_array_unique.Length (fun i -> (ngram_array_unique.[i], ngram_list |> List.filter(fun item -> item = ngram_array_unique.[i]) |> List.length) )

    Read the article

  • Deserialize xml which uses attribute name/value pairs

    - by Bodyloss
    My application receives a constant stream of xml files which are more or less a direct copy of the database record <record type="update"> <field name="id">987654321</field> <field name="user_id">4321</field> <field name="updated">2011-11-24 13:43:23</field> </record> And I need to deserialize this into a class which provides nullable property's for all columns class Record { public long? Id { get; set; } public long? UserId { get; set; } public DateTime? Updated { get; set; } } I just cant seem to work out a method of doing this without having to parse the xml file manually and switch on the field's name attribute to store the values. Is their a way this can be achieved quickly using an XmlSerializer? And if not is their a more efficient way of parsing it manually? Regards and thanks My main problem is that the attribute name needs to have its value set to a property name and its value as the contents of a <field>..</field> element

    Read the article

  • How do people handle foreign keys on clients when synchronizing to master db

    - by excsm
    Hi, I'm writing an application with offline support. i.e. browser/mobile clients sync commands to the master db every so often. I'm using uuid's on both client and server-side. When synching up to the server, the servre will return a map of local uuids (luid) to server uuids (suid). Upon receiving this map, clients updated their records suid attributes with the appropriate values. However, say a client record, e.g. a todo, has an attribute 'list_id' which holds the foreign key to the todos' list record. I use luids in foreign_keys on clients. However, when that attribute is sent over to the server, it would dirty the server db with luids rather than the suid the server is using. My current solution, is for the master server to keep a record of the mappings of luids to suids (per client id) and for each foreign key in a command, look up the suid for that particular client and use the suid instead. I'm wondering wether others have come across thus problem and if so how they have solved it? Is there a more efficient, simpler way? I took a look at this question "Synchronizing one or more databases with a master database - Foreign keys (5)" and someone seemed to suggest my current solution as one option, composite keys using suids and autoincrementing sequences and another option using -ve ids for client ids and then updating all negative ids with the suids. Both of these other options seem like a lot more work. Thanks, Saimon

    Read the article

  • Implementation of MVC with SQLite and NSURLConnection, use cases?

    - by user324723
    I'm interested in knowing how others have implemented/designed database & web services in their iphone app and how they simplified it for the entire application. My application is dependent on these services and I can't figure out a efficient way to use them together due to the (semi)complexity of my requirements. My past attempts on combining them haven't been completely successful or at least optimal in my mind. I'm building a database driven iphone app that uses a relational database in sqlite and consumes web services based on missing content or user interaction. Like this hasn't been done before...right? Since I am using a relational database - any web services consumed requires normalization, parsing the result and persisting it to the database before it can be displayed in a table view controller. The applications UI consists of nested(nav controller) table views where a user can select a cell and be taken to the next table view where it attempts to populate the table views data source from the database. If nothing exists in the database then it will send a request via web services to download its content, thus download - parse - persist - query - display. Since the user has the ability to request a refresh of this data it still requires the same process. Quickly describing what I've implemented and tried to run with - 1st attempt - Used a singleton web service class that handled sending web service requests, parsing the result and returning it to the table view controller via delegate protocols. Once the controller received that data it would then be responsible for persisting it to the database and re-returning the result. I didn't like the idea of only preventing the case where the app delegate selector doesn't exists(released) causing the app to crash. 2nd attempt - Used NSNotificationCenter for easy access to both database and web services but later realized it was more complex due to adding and removing observers per view(which isn't advised anyways).

    Read the article

  • Set a datetime for next or previous sunday at specific time

    - by Marc
    I have an app where there is always a current contest (defined by start_date and end_date datetime). I have the following code in the application_controller.rb as a before_filter. def load_contest @contest_last = Contest.last @contest_last.present? ? @contest_leftover = (@contest_last.end_date.utc - Time.now.utc).to_i : @contest_leftover = 0 if @contest_last.nil? Contest.create(:start_date => Time.now.utc, :end_date => Time.now.utc + 10.minutes) elsif @contest_leftover < 0 @winner = Organization.order('votes_count DESC').first @contest_last.update_attributes!(:organization_id => @winner.id, :winner_votes => @winner.votes_count) if @winner.present? Organization.update_all(:votes_count => 0) Contest.create(:start_date => @contest_last.end_date.utc, :end_date => Time.now.utc + 10.minutes) end end My questions: 1) I would like to change the :end_date to something that signifies next Sunday at a certain time (eg. next Sunday at 8pm). Similarly, I could then set the :start_date to to the previous Sunday at a certain time. I saw that there is a sunday() class (http://api.rubyonrails.org/classes/Time.html#method-i-sunday), but not sure how to specify a certain time on that day. 2) For this situation of always wanting the current contest, is there a better way of loading it in the app? Would caching it be better and then reloading if a new one is created? Not sure how this would be done, but seems to be more efficient. Thanks!

    Read the article

  • Refactoring - Speed increase

    - by Michael G
    How can I make this function more efficient. It's currently running at 6 - 45 seconds. I've ran dotTrace profiler on this specific method, and it's total time is anywhere between 6,000ms to 45,000ms. The majority of the time is spent on the "MoveNext" and "GetEnumerator" calls. and example of the times are 71.55% CreateTableFromReportDataColumns - 18, 533* ms - 190 calls -- 55.71% MoveNext - 14,422ms - 10,775 calls What can I do to speed this method up? it gets called a lot, and the seconds add up: private static DataTable CreateTableFromReportDataColumns(Report report) { DataTable table = new DataTable(); HashSet<String> colsToAdd = new HashSet<String> { "DataStream" }; foreach (ReportData reportData in report.ReportDatas) { IEnumerable<string> cols = reportData.ReportDataColumns.Where(c => !String.IsNullOrEmpty(c.Name)).Select(x => x.Name).Distinct(); foreach (var s in cols) { if (!String.IsNullOrEmpty(s)) colsToAdd.Add(s); } } foreach (string col in colsToAdd) { table.Columns.Add(col); } return table; }

    Read the article

  • Fast serarch of 2 dimensional array

    - by Tim
    I need a method of quickly searching a large 2 dimensional array. I extract the array from Excel, so 1 dimension represents the rows and the second the columns. I wish to obtain a list of the rows where the columns match certain criteria. I need to know the row number (or index of the array). For example, if I extract a range from excel. I may need to find all rows where column A =”dog” and column B = 7 and column J “a”. I only know which columns and which value to find at run time, so I can’t hard code the column index. I could use a simple loop, but is this efficient ? I need to run it several thousand times, searching for different criteria each time. For r As Integer = 0 To UBound(myArray, 0) - 1 match = True For c = 0 To UBound(myArray, 1) - 1 If not doesValueMeetCriteria(myarray(r,c) then match = False Exit For End If Next If match Then addRowToMatchedRows(r) Next The doesValueMeetCriteria function is a simple function that checks the value of the array element against the query requirement. e.g. Column A = dog etc. Is it more effiecent to create a datatable from the array and use the .select method ? Can I use Linq in some way ? Perhaps some form of dictionary or hashtable ? Or is the simple loop the most effiecent ? Your suggestions are most welcome.

    Read the article

  • Why is BorderLayout calling setSize() and setBounds()?

    - by ags
    I'm trying to get my head around proper use of the different LayoutManagers to make my GUI design skills more efficient and effective. For me, that usually requires a detailed understanding of what is going on under the hood. I've found some good discussion of the interaction and consequences of a Container using BorderLayout containing a Container using FlowLayout. I understand it for the most part, but wanted to confirm my mental model and to do so I am looking at the code for BorderLayout. In the code snippet below taken from BorderLayout.layoutContainer(), note the calls to the child Component's setSize() method followed by setBounds(). Looking at the source for these methods of Component, setSize() actually calls setBounds() with the current values for Component.x and Component.y. Why is this done (and not entirely redudant?) Doesn't the setBounds() call completely overwrite the results of the setSize() call? if ((c=getChild(NORTH,ltr)) != null) { c.setSize(right - left, c.height); Dimension d = c.getPreferredSize(); c.setBounds(left, top, right - left, d.height); top += d.height + vgap; } I'm also tring to understand where/when the child Component's size is initially set (before the LayoutManager.layoutContainer() method is called). Finally, this post itself raises a "meta-question": in a situation like this, where the source is available elsewhere, is the accepteed protocol to include the entire method? Or some other way to make it easier for folks to participate in the thread? Thanks.

    Read the article

  • Internal loop only runs once, containing loop runs endlessly

    - by Mark
    noob question I'm afraid. I have a loop that runs and rotates the hand of a clock and an internal loop that checks the angle of the hand if it is 90, 180, 270 and 360. On these 4 angles the corresponding div is displayed and its siblings removed. The hand loops and loops eternally, which is what I want, but the angle check only runs the loop once through the whole 360. As the hand passes through the angles it is correctly displaying and removing divs but is doesn't continue after the first revolution of the clock. I've obviously messed up somewhere and there is bound to be a more efficient way of doing all this. I am using jQueryRotate.js for my rotations. Thanks for your time. jQuery(document).ready(function(){ var angle = 0; setInterval(function(){ jQuery("#hand").rotate(angle); function movehand(){ if (angle == 90) { jQuery("#intervention").fadeIn().css("display","block").siblings().css("display","none"); } else if (angle == 180) { jQuery("#management").fadeIn().css("display","block").siblings().css("display","none"); } else if (angle == 270) { jQuery("#prevention").fadeIn().css("display","block").siblings().css("display","none"); } else if (angle == 360) { jQuery("#reaction").fadeIn().css("display","block").siblings().css("display","none"); } else {movehand;} }; movehand(); angle+=1; },10); });

    Read the article

  • How to Treat Race Condition of Session in Web Application?

    - by Morgan Cheng
    I was in a ASP.NET application has heavy traffic of AJAX requests. Once a user login our web application, a session is created to store information of this user's state. Currently, our solution to keep session data consistent is quite simple and brutal: each request needs to acquire a exclusive lock before being processed. This works fine for tradition web application. But, when the web application turns to support AJAX, it turns to not efficient. It is quite possible that multiple AJAX requests are sent to server at the same time without reloading the web page. If all AJAX requests are serialized by the exclusive lock, the response is not so quick. Anyway, many AJAX requests that doesn't access same session variables are blocked as well. If we don't have a exclusive lock for each requests, then we need to treat all race condition carefully to avoid dead lock. I'm afraid that would make the code complex and buggy. So, is there any best practice to keep session data consistent and keep code simple and clean?

    Read the article

  • JavaScript - Efficiently find all elements containing one of a large set of strings

    - by noah
    I have a set of strings and I need to find all all of the occurrences in an HTML document. Where the string occurs is important because I need to handle each case differently: String is all or part of an attribute. e.g., the string is foo: <input value="foo"> - Add class ATTR to the element. String is the full text of an element. e.g., <button>foo</button> - Add class TEXT to the element. String is inline in the text of an element. e.g., <p>I love foo</p> - Wrap the text in a span tag with class TEXT. Also, I need to match the longest string first. e.g., if I have foo and foobar, then <p>I love foobar</p> should become <p>I love <span class="TEXT">foobar</span></p>, not <p>I love <span class="TEXT">foo</span>bar</p>. The inline text is easy enough: Sort the strings descending by length and find and replace each in document.body.innerHTML with <span class="TEXT">$1</span>, although I'm not sure if that is the most efficient way to go. For the attributes, I can do something like this: sortedStrings.each(function(it) { document.body.innerHTML.replace(new RegExp('(\S+?)="[^"]*'+escapeRegExChars(it)+'[^"]*"','g'),function(s,attr) { $('[+attr+'*='+it+']').addClass('ATTR'); }); }); Again, that seems inefficient. Lastly, for the full text elements, a depth first search of the document that compares the innerHTML to each string will work, but for a large number of strings, it seems very inefficient. Any answer that offers performance improvements gets an upvote :)

    Read the article

  • A good data model for finding a user's favorite stories

    - by wings
    Original Design Here's how I originally had my Models set up: class UserData(db.Model): user = db.UserProperty() favorites = db.ListProperty(db.Key) # list of story keys # ... class Story(db.Model): title = db.StringProperty() # ... On every page that displayed a story I would query UserData for the current user: user_data = UserData.all().filter('user =' users.get_current_user()).get() story_is_favorited = (story in user_data.favorites) New Design After watching this talk: Google I/O 2009 - Scalable, Complex Apps on App Engine, I wondered if I could set things up more efficiently. class FavoriteIndex(db.Model): favorited_by = db.StringListProperty() The Story Model is the same, but I got rid of the UserData Model. Each instance of the new FavoriteIndex Model has a Story instance as a parent. And each FavoriteIndex stores a list of user id's in it's favorited_by property. If I want to find all of the stories that have been favorited by a certain user: index_keys = FavoriteIndex.all(keys_only=True).filter('favorited_by =', users.get_current_user().user_id()) story_keys = [k.parent() for k in index_keys] stories = db.get(story_keys) This approach avoids the serialization/deserialization that's otherwise associated with the ListProperty. Efficiency vs Simplicity I'm not sure how efficient the new design is, especially after a user decides to favorite 300 stories, but here's why I like it: A favorited story is associated with a user, not with her user data On a page where I display a story, it's pretty easy to ask the story if it's been favorited (without calling up a separate entity filled with user data). fav_index = FavoriteIndex.all().ancestor(story).get() fav_of_current_user = users.get_current_user().user_id() in fav_index.favorited_by It's also easy to get a list of all the users who have favorited a story (using the method in #2) Is there an easier way? Please help. How is this kind of thing normally done?

    Read the article

  • VB.NET Syntax Coding

    - by Yiu Korochko
    I know many people ask how some of these are done, but I do not understand the context in which to use the answers, so... I'm building a code editor for a subversion of Python language, and I found a very decent way of highlighting keywords in the RichTextBox through this: bluwords.Add(KEYWORDS GO HERE) If scriptt.Text.Length > 0 Then Dim selectStart2 As Integer = scriptt.SelectionStart scriptt.Select(0, scriptt.Text.Length) scriptt.SelectionColor = Color.Black scriptt.DeselectAll() For Each oneWord As String In bluwords Dim pos As Integer = 0 Do While scriptt.Text.ToUpper.IndexOf(oneWord.ToUpper, pos) >= 0 pos = scriptt.Text.ToUpper.IndexOf(oneWord.ToUpper, pos) scriptt.Select(pos, oneWord.Length) scriptt.SelectionColor = Color.Blue pos += 1 Loop Next scriptt.SelectionStart = selectStart2 End If (scriptt is the richtextbox) But when any decent amount of code is typed (or loaded via OpenFileDialog) chunks of the code go missing, the syntax selection falls apart, and it just plain ruins it. I'm looking for a more efficient way of doing this, maybe something more like visual studio itself...because there is NO NEED to highlight all text, set it black, then redo all of the syntaxing, and the text begins to over-right if you go back to insert characters between text. Also, in this version of Python, hash (#) is used for comments on comment only lines and double hash (##) is used for comments on the same line. Now I saw that someone had asked about this exact thing, and the working answer to select to the end of the line was something like: ^\'[^\r\n]+$|''[^\r\n]+$ which I cannot seem to get into practice. I also wanted to select text between quotes and turn it turquoise, such as between the first quotation mark and the second, the text is turquoise, and the same between the 3rd and 4th etcetera... Any help is appreciated!

    Read the article

  • SQL Structure of DB table with different types of columns

    - by Dmitry Dvornikov
    I have a problem with the optimization of the structure of the database. I'll try to explain it exactly. I create a project, where we can add different values??, but this values must have different types of the columns in the database (eg, int, double , varchar). What is the best way to store the different types of values ??in the database. In the project I'm using Propel 1.6. The point is availability to add value with 'int', 'varchar' and other columns types, to search the table was efficient. In total, I have two ideas. The first is to create a table of "value", which will have columns: "id ", "value_int", "value_double", "value_varchar", etc - with the corresponding column types. Depending on the type of values??, records will be saved with the value in the appropriate column (the rest will be NULL). The second solution is to create separate tables such as "value_int", "value_varchar" etc. There would be columns: "id", "value", which correspond to the relevant types of "value" (ie, such as int, varchar, etc). I must admit that I do not believe any of the above solutions, originally I was thinking about one table "value", where the column would be a "text" type - but this solution would probably be even worse. I would like to know your opinion on this topic, maybe something else would be better. Thanks in advance. EDIT: For example : We have three tables: USER: [table of users] * id * name FIELD: [table of profile fields - where the column 'type' is the type of field, eg int or varchar) * id * type * name VALUE : * id * User_id - ( FK user.id ) * Field_id - ( FK field.id ) * value So we have in each row an user in USER table, and the profile is stored in the VALUE table. Bit each profile field may have a different type (column 'type' in the FIELD table), and based on that I would want this value to add to the appropriate column of the appropriate type.

    Read the article

  • [MySQL] Efficiently store last X records per item

    - by Saif Bechan
    I want to store the last X records in an MySQL database in an efficient way. So when the 4th record is stored the first should be deleted. The way I do this not is first run a query getting the items. Than check what I should do then insert/delete. There has to be a better way to do this. Any suggestions? Edit I think I should add that the records stored do not have a unique number. They have a mixed par. For example article_id and user_id. Then I want to make a table with the last X items for user_x. Just selecting the article from the table grouped by user and sorted by time is not an option for me. The table where I do the sort and group on has millions of records and gets hit a lot for no reason. So making a table in between with the last X records is way more effient. PS. I am not using this for articles and users.

    Read the article

  • Help ! How do I get the total number rows from my mssql paging procedure ?

    - by The_AlienCoder
    Ok I have a table in my MSSQL database that stores comments. My desire is to be able to page though the records using [Back],[Next], page numbers & [Last] buttons in my datalist. I figured the most efficient way was to use a stored procedure that only returns a certain number of rows within a partcular range. Here is what I came up with @PageIndex INT, @PageSize INT, @postid int AS SET NOCOUNT ON begin WITH tmp AS ( SELECT comments.*, ROW_NUMBER() OVER (ORDER BY dateposted ASC) AS Row FROM comments WHERE (comments.postid = @postid)) SELECT tmp.* FROM tmp WHERE Row between (@PageIndex - 1) * @PageSize + 1 and @PageIndex*@PageSize end RETURN Now everything works fine and I have been able implement [Next] and [Back] buttons in my datalist pager.Now I need the total number of all comments(not in the cuurent page) so that I can implement my page numbers and the[Last] button on my pager. In other words I want to return the total number of rows in my first select statement i.e WITH tmp AS ( SELECT comments.*, ROW_NUMBER() OVER (ORDER BY dateposted ASC) AS Row FROM comments WHERE (comments.postid = @postid)) set @TotalRows = @@rowcount @@rowcount doesnt work and raises an error.I also cant get count.* to work either. Is there another way to get the total amount of rows or is my approach doomed.

    Read the article

  • CUDA - multiple kernels to compute a single value

    - by Roger
    Hey, I'm trying to write a kernel to essentially do the following in C float sum = 0.0; for(int i = 0; i < N; i++){ sum += valueArray[i]*valueArray[i]; } sum += sum / N; At the moment I have this inside my kernel, but it is not giving correct values. int i0 = blockIdx.x * blockDim.x + threadIdx.x; for(int i=i0; i<N; i += blockDim.x*gridDim.x){ *d_sum += d_valueArray[i]*d_valueArray[i]; } *d_sum= __fdividef(*d_sum, N); The code used to call the kernel is kernelName<<<64,128>>>(N, d_valueArray, d_sum); cudaMemcpy(&sum, d_sum, sizeof(float) , cudaMemcpyDeviceToHost); I think that each kernel is calculating a partial sum, but the final divide statement is not taking into account the accumulated value from each of the threads. Every kernel is producing it's own final value for d_sum? Does anyone know how could I go about doing this in an efficient way? Maybe using shared memory between threads? I'm very new to GPU programming. Cheers

    Read the article

  • odp.net SQL query retrieve set of rows from two input arrays.

    - by Karl Trumstedt
    I have a table with a primary key consisting of two columns. I want to retrieve a set of rows based on two input arrays, each corresponding to one primary key column. select pkt1.id, pkt1.id2, ... from PrimaryKeyTable pkt1, table(:1) t1, table(:2) t2 where pkt1.id = t1.column_value and pkt1.id2 = t2.column_value I then bind the values with two int[] in odp.net. This returns all different combinations of my resulting rows. So if I am expecting 13 rows I receive 169 rows (13*13). The problem is that each value in t1 and t2 should be linked. Value t1[4] should be used with t2[4] and not all the different values in t2. Using distinct solves my problem, but I'm wondering if my approach is wrong. Anyone have any pointers on how to solve this the best way? One way might be to use a for-loop accessing each index in t1 and t2 sequentially, but I wonder what will be more efficient. Edit: actually distinct won't solve my problem, it just did it based on my input-values (all values in t2 = 0)

    Read the article

  • Good way to identify similar images?

    - by Nick
    I've developed a simple and fast algorithm in PHP to compare images for similarity. Its fast (~40 per second for 800x600 images) to hash and a unoptimised search algorithm can go through 3,000 images in 22 mins comparing each one against the others (3/sec). The basic overview is you get a image, rescale it to 8x8 and then convert those pixels for HSV. The Hue, Saturation and Value are then truncated to 4 bits and it becomes one big hex string. Comparing images basically walks along two strings, and then adds the differences it finds. If the total number is below 64 then its the same image. Different images are usually around 600 - 800. Below 20 and extremely similar. Are there any improvements upon this model I can use? I havent looked at how relevant the different components (hue, saturation and value) are to the comparison. Hue is probably quite important but the others? To speed up searches I could probably split the 4 bits from each part in half, and put the most significant bits first so if they fail the check then the lsb doesnt need to be checked at all. I dont know a efficient way to store bits like that yet still allow them to be searched and compared easily. I've been using a dataset of 3,000 photos (mostly unique) and there havent been any false positives. Its completely immune to resizes and fairly resistant to brightness and contrast changes.

    Read the article

  • gl_FragColor and glReadPixels

    - by chun0216
    I am still trying to read pixels from fragment shader and I have some questions. I know that gl_FragColor returns with vec4 meaning RGBA, 4 channels. After that, I am using glReadPixels to read FBO and write it in data GLubyte *pixels = new GLubyte[640*480*4]; glReadPixels(0, 0, 640,480, GL_RGBA, GL_UNSIGNED_BYTE, pixels); This works fine but it really has speed issue. Instead of this, I want to just read RGB so ignore alpha channels. I tried: GLubyte *pixels = new GLubyte[640*480*3]; glReadPixels(0, 0, 640,480, GL_RGB, GL_UNSIGNED_BYTE, pixels); instead and this didn't work though. I guess it's because gl_FragColor returns 4 channels and maybe I should do something before this? Actually, since my returned image (gl_FragColor) is grayscale, I did something like float gray = 0.5 //or some other values gl_FragColor = vec4(gray,gray,gray,1.0); So is there any efficient way to use glReadPixels instead of using the first 4 channels method? Any suggestion? By the way, this is on opengl es 2.0 code.

    Read the article

  • Faster quadrature decoder loops with Python code

    - by Kelei
    I'm working with a BeagleBone Black and using Adafruit's IO Python library. Wrote a simple quadrature decoding function and it works perfectly fine when the motor runs at about 1800 RPM. But when the motor runs at higher speeds, the code starts missing some of the interrupts and the encoder counts start to accumulate errors. Do you guys have any suggestions as to how I can make the code more efficient or if there are functions which can cycle the interrupts at a higher frequency. Thanks, Kel Here's the code: # Define encoder count function def encodercount(term): global counts global Encoder_A global Encoder_A_old global Encoder_B global Encoder_B_old global error Encoder_A = GPIO.input('P8_7') # stores the value of the encoders at time of interrupt Encoder_B = GPIO.input('P8_8') if Encoder_A == Encoder_A_old and Encoder_B == Encoder_B_old: # this will be an error error += 1 print 'Error count is %s' %error elif (Encoder_A == 1 and Encoder_B_old == 0) or (Encoder_A == 0 and Encoder_B_old == 1): # this will be clockwise rotation counts += 1 print 'Encoder count is %s' %counts print 'AB is %s %s' % (Encoder_A, Encoder_B) elif (Encoder_A == 1 and Encoder_B_old == 1) or (Encoder_A == 0 and Encoder_B_old == 0): # this will be counter-clockwise rotation counts -= 1 print 'Encoder count is %s' %counts print 'AB is %s %s' % (Encoder_A, Encoder_B) else: #this will be an error as well error += 1 print 'Error count is %s' %error Encoder_A_old = Encoder_A # store the current encoder values as old values to be used as comparison in the next loop Encoder_B_old = Encoder_B # Initialize the interrupts - these trigger on the both the rising and falling GPIO.add_event_detect('P8_7', GPIO.BOTH, callback = encodercount) # Encoder A GPIO.add_event_detect('P8_8', GPIO.BOTH, callback = encodercount) # Encoder B # This is the part of the code which runs normally in the background while True: time.sleep(1)

    Read the article

  • mysql image disable print download

    - by Vish
    Hi, We use a Flex AIR client and a WAMP server. Tiff images are stored in MySQL. Currently, I can download the image from AIR client and it prompts for a download dialog. Things are fine till this point. We got a new requirement. Requirement is that only some users can print the image which gets downloaded. For other users, they should not be able to print the tiff image. Wondering how to accomplish this. One idea, not sure if its efficient, is to convert the image requested to pdf at the server side, disable print option there(hope there are API's available) and send back the pdf. Please let me know btter ideas. Also, is there a way to prevent file download dialog from popping up everytime the file is requested for download? Can we just get the file stream to the client and manipulate it to open with a particular viewer or write it to pdf... Please help.

    Read the article

  • Mimic Coldfusion's debug output in PHP?

    - by TekiusFanatikus
    I'm trying to mimic Coldfusion's debug output in PHP. Here's an example of what it looks like (ie. Execution Time section): I've turned to XDebug. Ideally, the exception stack error output would be what I'd be looking for. However, it only shows up when an exception occurs. I also tried something like (in our CMS-ish app) this (original question here): $content.= "<?php xdebug_start_trace('e:/xdebug/trace');?>"; $content.= "<?php require('".$page['file_'.LG]."'); ?>"; $content.= "<?php xdebug_stop_trace();?>"; ... $content.= "<?php echo readfile('e:/xdebug/trace.xt');?>"; However, I get an insane, browser crashing HTML table dropped at the bottom of page. Not very efficient. My php.ini config: xdebug.trace_format = 2 xdebug.collect_vars = 1 xdebug.collect_params = 4 xdebug.dump_globals = 1 xdebug.dump.SERVER = 'REQUEST_URI' xdebug.show_local_vars = 1 xdebug.show_mem_delta = 1 I'm just wondering if someone has already done something similar?

    Read the article

< Previous Page | 510 511 512 513 514 515 516 517 518 519 520 521  | Next Page >