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  • LINQ Query vs Lambda Expression

    - by FosterZ
    What is the difference between the following two snippets (i.e LINQ Query vs Lambda Expression) LINQ Query public Product GetProduct(int productID) { AdventureWorksDBDataContext db = new AdventureWorksDBDataContext(); Product product = (from p in db.Products where p.ProductID == productID select p).Single(); return product; } Using a Lambda expression public Product GetProduct(int productID) { AdventureWorksDBDataContext db = new AdventureWorksDBDataContext(); Product product = db.Products.Single(p = p.ProductID == productID); return product; }

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  • what is the point of heterogenous arrays?

    - by aharon
    I know that more-dynamic-than-Java languages, like Python and Ruby, often allow you to place objects of mixed types in arrays, like so: ["hello", 120, ["world"]] What I don't understand is why you would ever use a feature like this. If I want to store heterogenous data in Java, I'll usually create an object for it. For example, say a User has int ID and String name. While I see that in Python/Ruby/PHP you could do something like this: [["John Smith", 000], ["Smith John", 001], ...] this seems a bit less safe/OO than creating a class User with attributes ID and name and then having your array: [<User: name="John Smith", id=000>, <User: name="Smith John", id=001>, ...] where those <User ...> things represent User objects. Is there reason to use the former over the latter in languages that support it? Or is there some bigger reason to use heterogenous arrays? N.B. I am not talking about arrays that include different objects that all implement the same interface or inherit from the same parent, e.g.: class Square extends Shape class Triangle extends Shape [new Square(), new Triangle()] because that is, to the programmer at least, still a homogenous array as you'll be doing the same thing with each shape (e.g., calling the draw() method), only the methods commonly defined between the two.

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  • How to manipulate *huge* amounts of data

    - by Alejandro
    Hi there! I'm having the following problem. I need to store huge amounts of information (~32 GB) and be able to manipulate it as fast as possible. I'm wondering what's the best way to do it (combinations of programming language + OS + whatever you think its important). The structure of the information I'm using is a 4D array (NxNxNxN) of double-precission floats (8 bytes). Right now my solution is to slice the 4D array into 2D arrays and store them in separate files in the HDD of my computer. This is really slow and the manipulation of the data is unbearable, so this is no solution at all! I'm thinking on moving into a Supercomputing facility in my country and store all the information in the RAM, but I'm not sure how to implement an application to take advantage of it (I'm not a professional programmer, so any book/reference will help me a lot). An alternative solution I'm thinking on is to buy a dedicated server with lots of RAM, but I don't know for sure if that will solve the problem. So right now my ignorance doesn't let me choose the best way to proceed. What would you do if you were in this situation? I'm open to any idea. Thanks in advance!

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  • cakephp read and display from more than one related table

    - by z22
    I have 2 tables Users and Artists. User: id name password city_id state_id country_id Artist: id user_id description I wish to create add and edit form(single form acts as add and edit). But on click of edit link, I wish to fill in the form fields from user as well as artist table. How do i do that? Below is my controller code: public function artist_register() { $this->country_list(); if ($this->request->is('post')) { $this->request->data['User']['group_id'] = 2; if ($this->{$this->modelClass}->saveAll($this->request->data)) { $this->redirect(array('controller' => 'Users', 'action' => 'login')); } } $this->render('artist_update'); } public function artist_update($id) { $artist = $this->{$this->modelClass}->findByuser_id($id); $artist_id = $artist[$this->modelClass]['id']; if($this->request->is('get')) { $this->request->data = $this->{$this->modelClass}->read(null, $artist_id); $this->request->data = $this->{$this->modelClass}->User->read(null, $id); } else { if($this->{$this->modelClass}->save($this->request->data)) { $this->Session->setFlash('Your Profile has been updated'); $this->redirect(array('action' => 'index')); } } } The code doesnt work. how do i solve it?

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  • Why Can I Change Struct's int[] Property from Method Without Specifying "ref"?

    - by AMissico
    From a method, I can pass a struct which contains an array of integers, and change the values in the array. I am not sure I understand fully why I can do this. Can someone please explain why I can change the values stored in the int[]? private void DoIt(){ SearchInfo a = new SearchInfo(); a.Index = 1; a.Map = new int[] { 1 }; SearchInfo b = new SearchInfo(); b.Index = 1; b.Map = new int[] { 1 }; ModifyA(a); ModifyB(ref b); Debug.Assert(a.Index == 1); Debug.Assert(a.Map[0] == 1, "why did this change?"); Debug.Assert(b.Index == 99); Debug.Assert(b.Map[0] == 99); } void ModifyA(SearchInfo a) { a.Index = 99; a.Map[0] = 99; } void ModifyB(ref SearchInfo b) { b.Index = 99; b.Map[0] = 99; } struct SearchInfo { public int[] Map; public int Index; }

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  • format result of dat calc in linq

    - by d daly
    Hi I have a calculation in a linq query, although it brings back the correct nuber of days, Im not sure how to better format it select new { time = (System.DateTime.Today - cs.date_case_opened), }; just now it shows eg 4:00:00:00 if the difference is 4 days, any ideas how i can present this better? thanks

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  • Variable amount of columns returned in mysqli prepared statement

    - by manyxcxi
    I have a situation where a dynamic query is being generated that could select anywhere from 1 to over 300 different columns across multiple tables. It currently works fine just doing a query, however the issue I'm running into in using a prepared statement is that I do not know how to handle the fact that I don't know how many columns I will be asking for each time and therefor don't know how to process the results. The reason I believe a bind statement will help is because once this query is run once, it will most likely (though not always) be run again with the exact same parameters. Currently I have something like this: $rows = array(); $this->statement = $this->db->prepare($query); $this->statement->bind_param('i',$id); $this->statement->execute(); $this->statement->bind_result($result); while($this->statement->fetch()) { $rows[] = $result; } I know this doesn't work as I want it to, my question is how do I get the data back out of the query. Is it possible to bring the columns back in an associative array by column name, like a standard mysqli query?

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  • Handle row deletion in UITableViewController

    - by Kamchatka
    Hello, I hava a UINavigationController. The first level is a UITableViewController, the second level just shows details on one of the items of the table view. In this detail view, I can delete the item. It deletes the underlying managed object. When I pop back to the view, I have a crash. I understand why, it's because I didn't update the cached array that contains the data. I looked at several tutorials and I don't exactly understand how am I supposed to handle deletion. Maybe I don't understand exactly where I should fetch the objects in the model. Should I do a query for every cellForRowAtIndexPath and take the item in the result at position indexPath.row? It doesn't look efficient. Should I check for changes somewhere and recache the whole query in an array. I would think CoreData would provide something more natural but I couldn't find it so far. Thanks in advance.

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  • How to get a handle to all JCheckBox objects in order to loop?

    - by EmmyS
    I'm very new to Java and am having some issues looping through JCheckBoxes on a UI. The idea is that I have a bunch of checkboxes (not in a group because more than one can be selected.) When I click a JButton, I want to build a string containing the text from each selected checkbox. The issue I'm having is that our instructor told us that the checkboxes need to be created via a method, which means (see code below) that there isn't a discrete instance name for each checkbox. If there were, I could say something like if(checkBox1.isSelected()) { myString.append(checkBox.getText()); } That would repeat for checkBox2, checkBox3, and so on. But the method provided to us for adding checkboxes to a panel looks like this: public class CheckBoxPanel extends JPanel { private static final long serialVersionUID = 1L; public CheckBoxPanel(String title, String... options) { setBorder(BorderFactory.createTitledBorder(BorderFactory .createEtchedBorder(), title)); setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); // make one checkbox for each option for (String option : options) { JCheckBox b = new JCheckBox(option); b.setActionCommand(option); add(b); } } } This is called like this: toppingPanel = new CheckBoxPanel("Each Topping $1.50", "Tomato", "Green Pepper", "Black Olives", "Mushrooms", "Extra Cheese", "Pepperoni", "Sausage"); So I now have a panel that contains a border with the title "Each Topping $1.50", and 7 visible checkboxes. What I need to do is get a list of all the selected toppings. We are not supposed to use an ActionListener for each checkbox, but rather get the list when a button is clicked. I'm feeling really clueless here, but I just can't figure out how to get the isSelected property of the checkboxes when the individual checkboxes don't have instance names. Ideally I'd like to somehow add all the checkboxes to an array and loop through the array in the button's action listener to determine which ones are checked, but if I have to check each one individually I will. I just can't figure out how to refer to an individual checkbox when they've been created dynamically.

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  • Combinatorial optimisation of a distance metric

    - by Jose
    I have a set of trajectories, made up of points along the trajectory, and with the coordinates associated with each point. I store these in a 3d array ( trajectory, point, param). I want to find the set of r trajectories that have the maximum accumulated distance between the possible pairwise combinations of these trajectories. My first attempt, which I think is working looks like this: max_dist = 0 for h in itertools.combinations ( xrange(num_traj), r): for (m,l) in itertools.combinations (h, 2): accum = 0. for ( i, j ) in itertools.izip ( range(k), range(k) ): A = [ (my_mat[m, i, z] - my_mat[l, j, z])**2 \ for z in xrange(k) ] A = numpy.array( numpy.sqrt (A) ).sum() accum += A if max_dist < accum: selected_trajectories = h This takes forever, as num_traj can be around 500-1000, and r can be around 5-20. k is arbitrary, but can typically be up to 50. Trying to be super-clever, I have put everything into two nested list comprehensions, making heavy use of itertools: chunk = [[ numpy.sqrt((my_mat[m, i, :] - my_mat[l, j, :])**2).sum() \ for ((m,l),i,j) in \ itertools.product ( itertools.combinations(h,2), range(k), range(k)) ]\ for h in itertools.combinations(range(num_traj), r) ] Apart from being quite unreadable (!!!), it is also taking a long time. Can anyone suggest any ways to improve on this?

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  • LINQ entity query performance

    - by Abdel Olakara
    Hi all, I have a silly question. I would like to know if there is performance deference in these two quries: var cObject = from cust in entities.Customer where cust.id == cid select cust; and var cObject = entities.Customer.First( c=> c.id == cid); My query return only one record as I am querying with the primary key. But do they make any difference?

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  • Core Data - 'calculated' attributes

    - by nephilim
    I have two entities: A and B A has two properties from and to, both pointing to the B entity. B as a fetched property to A with predicate from == $FETCH_SOURCE or to = $FETCH_SOURCE -- (from) -> A -- (to) -> B <- (As) -- In my application I select a certain B instance, and then show all of its A instances. Now, in my table the columns are bound to an array controller containing the selected A instances. I want to 'merge' the from and to columns. I already know one of the columns will be equal to the selected B instance, so now I'm only interested in the second value. The options I see: create a custom class for the B entity and create a method that returns either value. It should somehow be able to retrieve which B instance is currently selected. create a custom DataSource. Most columns are still using bindings, so then we'd have to access the NSArrayController's array so we're sure we have the right object. create a custom DataSource, remove the NSArrayController and do all the Core Data stuff ourselves. Is there any 'right' way to solve this?

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  • Const unsigned char* to char8

    - by BSchlinker
    So, I have two types at the moment: const unsigned char* unencrypted_data_char; string unencrypted_data; I'm attempting to perform a simple conversion of data from one to the other (string - const unsigned char*) As a result, I have the following: strcpy((unencrypted_data_char),(unencrypted_data.c_str())); However, I'm receiving the error: error C2664: 'strcpy' : cannot convert parameter 1 from 'const unsigned char *' to 'char *' Any advise? I thought using reinterpret_cast would help, but it doesn't seem to make a difference.

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  • Specifying schema for temporary tables

    - by Tom Hunter
    I'm used to seeing temporary tables created with just the hash/number symbol, like this: CREATE TABLE #Test ( [Id] INT ) However, I've recently come across stored procedure code that specifies the schema name when creating temporary tables, for example: CREATE TABLE [dbo].[#Test] ( [Id] INT ) Is there any reason why you would want to do this? If you're only specifying the user's default schema, does it make any difference? Does this refer to the [dbo] schema in the local database or the tempdb database?

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  • Designing a general database interface in PHP

    - by lamas
    I'm creating a small framework for my web projects in PHP so I don't have to do the basic work over and over again for every new website. It is not my goal to create a second CakePHP or Codeigniter and I'm also not planning to build my websites with any of the available frameworks as I prefer to use things I've created myself in general. I have no problems in designing that framework when it comes to parts like the core structure, request handling, and so on but I'm getting stuck with designing the database interface for my modules. I've already thought about using the MVC pattern but thought that it would be a bit of a overkill. So the exact problem I'm facing is how my frameworks modules (viewCustomers could be a module, for example) should interact with the database. Is it a good idea to write SQL directly in PHP (mysql_query( 'SELECT firstname, lastname(.....))? How could I abstract a query like SELECT firstname, lastname FROM customers WHERE id=X Would MySQL helper functions like $this->db->get( array('firstname', 'lastname'), array('id'=>X) ) be a good idea? I suppose not because they actually make everything more complicated by requiring arrays to be created and passed. Is the Model pattern from MVC my only real option?

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  • Does Perl auto-vivify variables used as references in subroutine calls?

    - by FM
    I've declared 2010 to be the year of higher-order programming, so I'm learning Haskell. The introduction has a slick quick-sort demo, and I thought, "Hey, that's easy to do in Perl". It turned to be easier than I expected. Note that I don't have to worry about whether my partitions ($less and $more) are defined. Normally you can't use an undefined value as an array reference. use strict; use warnings; use List::MoreUtils qw(part); my @data = (5,6,7,4,2,9,10,9,5,1); my @sorted = qsort(@data); print "@sorted\n"; sub qsort { return unless @_; my $pivot = shift @_; my ($less, $more) = part { $_ < $pivot ? 0 : 1 } @_; # Works, even though $less and $more are sometimes undefined. return qsort(@$less), $pivot, qsort(@$more); } As best I can tell, Perl will auto-vivify a variable that you try to use as a reference -- but only if you are passing it to a subroutine. For example, my call to foo() works, but not the attempted print. use Data::Dumper qw(Dumper); sub foo { print "Running foo(@_)\n" } my ($x); print Dumper($x); # Fatal: Can't use an undefined value as an ARRAY reference. # print @$x, "\n"; # But this works. foo(@$x); # Auto-vivification: $x is now []. print Dumper($x); My questions: Am I understanding this behavior correctly? What is the explanation or reasoning behind why Perl does this? Is this behavior explained anywhere in the docs?

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  • Google Spreadsheet API problem: memory exceeded

    - by Robbert
    Hi guys, Don't know if anyone has experience with the Google Spreadsheets API or the Zend_GData classes but it's worth a go: When I try to insert a value in a 750 row spreadsheet, it takes ages and then throws an error that my memory limit (which is 128 MB!) was exceeded. I also got this when querying all records of this spreadsheet but this I can imaging because it's quite a lot of data. But why does this happen when inserting a row? That's not too complex, is it? Here's the code I used: public function insertIntoSpreadsheet($username, $password, $spreadSheetId, $data = array()) { $service = Zend_Gdata_Spreadsheets::AUTH_SERVICE_NAME; $client = Zend_Gdata_ClientLogin::getHttpClient($username, $password, $service); $client->setConfig(array( 'timeout' => 240 )); $service = new Zend_Gdata_Spreadsheets($client); if (count($data) == 0) { die("No valid data"); } try { $newEntry = $service->insertRow($data, $spreadSheetId); return true; } catch (Exception $e) { return false; } }

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  • Preg_match differences?

    - by sky
    Hi, i want to ask, what is the meaning or difference between these two line? if( preg_match_all('/\#([?-?À-ÿ?-??-?a-z0-9\-_]{1,50})/iu', $message, $matches, PREG_PATTERN_ORDER) ) { if( preg_match_all('/\#([?-?a-z0-9\-_\x{4e00}-\x{9fa5}]{1,50})/iu', $message, $matches, PREG_PATTERN_ORDER) ) { and what does the number 3 mean in this line? (Arrow pointing) if( preg_match_all('/\@([a-zA-Z0-9\-_\x{4e00}-\x{9fa5}]{->3,30})/u', $message, $matches, PREG_PATTERN_ORDER) ) { Thanks!

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  • Python to C# with openSSL requirement

    - by fonix232
    Hey there again! Today I ran into a problem when I was making a new theme creator for chrome. As you may know, Chrome uses a "new" file format, called CRX, to manage it's plugins and themes. It is a basic zip file, but a bit modified: "Cr24" + derkey + signature + zipFile And here comes the problem. There are only two CRX creators, written in Ruby or Python. I don't know neither language too much (had some basic experience in Python though, but mostly with PyS60), so I would like to ask you to help me convert this python app to a C# class. Also, here is the source of crxmake.py: #!/usr/bin/python # Cribbed from http://github.com/Constellation/crxmake/blob/master/lib/crxmake.rb # and http://src.chromium.org/viewvc/chrome/trunk/src/chrome/tools/extensions/chromium_extension.py?revision=14872&content-type=text/plain&pathrev=14872 # from: http://grack.com/blog/2009/11/09/packing-chrome-extensions-in-python/ import sys from array import * from subprocess import * import os import tempfile def main(argv): arg0,dir,key,output = argv # zip up the directory input = dir + ".zip" if not os.path.exists(input): os.system("cd %(dir)s; zip -r ../%(input)s . -x '.svn/*'" % locals()) else: print "'%s' already exists using it" % input # Sign the zip file with the private key in PEM format signature = Popen(["openssl", "sha1", "-sign", key, input], stdout=PIPE).stdout.read(); # Convert the PEM key to DER (and extract the public form) for inclusion in the CRX header derkey = Popen(["openssl", "rsa", "-pubout", "-inform", "PEM", "-outform", "DER", "-in", key], stdout=PIPE).stdout.read(); out=open(output, "wb"); out.write("Cr24") # Extension file magic number header = array("l"); header.append(2); # Version 2 header.append(len(derkey)); header.append(len(signature)); header.tofile(out); out.write(derkey) out.write(signature) out.write(open(input).read()) os.unlink(input) print "Done." if __name__ == '__main__': main(sys.argv) Please could you help me?

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  • HTML Form HIdden Fields added with Javascript not POSTing

    - by dscher
    I have a form where the user can enter a link, click the "add link" button, and that link is then(via jQuery) added to the form as a hidden field. The problem is it's not POSTing when I submit the form. It's really starting to confound me. The thing is that if I hardcode a hidden field into the form, it is posted, but my function isn't working for some reason. The hidden field DOES get added to my form as I can see with Firebug but it's just not being sent with the POST data. Just to note, I'm using an array in Javascript to hold the elements until the form is submitted which also posts them visibly for the user to see what they've added. I'm using [] notation on the "name" field of the element because I want the links to feed into an array in PHP. Here is the link creation which is being appended to my form: function make_hidden_element_tag(item_type, item_content, item_id) { return '<input type="hidden" name="' + item_type + '[]" id="hidden_link_' + item_id + '" value="' + item_content + '"/>'; Does anyone have an idea why this might not be posting. As stated above, any hard-coded tags that are nearly identical to the above works fine, it's just that this tag isn't working. Here is how I'm adding the tag to the form with jQUery: $('#link_td').append( make_hidden_element_tag('links', link, link_array.length - 1)); I'm using the Kohana 3 framework, although I'm not sure that has any bearing on this because it's not really doing anything from the time the HTML is added to the page and the submit button is pressed.

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  • Overriding !important style using Javascript

    - by Enrico
    Title pretty much sums it up. The external style sheet has the following code: td.EvenRow a{ display: none !important; } I have tried using: element.style.display = "inline"; and element.style.display = "inline !important"; but neither works. Is it possible to override an !important style using javascript. This is for a greasemonkey extension, if that makes a difference. Much appreciated, Enrico

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  • How do I bind arrays to columns in a WPF datagrid

    - by user1432917
    I have a Log object that contains a list of Curve objects. Each curve has a Name property and an array of doubles. I want the Name to be in the column header and the data below it. I have a user control with a datagid. Here is the XAML; <UserControl x:Class="WellLab.UI.LogViewer" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" mc:Ignorable="d" d:DesignHeight="500" d:DesignWidth="500"> <Grid> <StackPanel Height="Auto" HorizontalAlignment="Stretch" Margin="0" Name="stackPanel1" VerticalAlignment="Stretch" Width="Auto"> <ToolBarTray Height="26" Name="toolBarTray1" Width="Auto" /> <ScrollViewer Height="Auto" Name="scrollViewer1" Width="Auto" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Visible" CanContentScroll="True" Background="#E6ABA4A4"> <DataGrid AutoGenerateColumns="True" Height="Auto" Name="logDataGrid" Width="Auto" ItemsSource="{Binding}" HorizontalAlignment="Left"> </DataGrid> </ScrollViewer> </StackPanel> </Grid> In the code behind I have figured out how to create columns and name them, but I have not figured out how to bind the data. public partial class LogViewer { public LogViewer(Log log) { InitializeComponent(); foreach (var curve in log.Curves) { var data = curve.GetData(); var col = new DataGridTextColumn { Header = curve.Name }; logDataGrid.Columns.Add(col); } } } I wont even show the code I tried to use to bind the array "data", since nothing even came close. I am sure I am missing something simple, but after hours of searching the web, I have to come begging for an answer.

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  • Are there any implementations of multiset for .Net?

    - by dangph
    I'm looking for a .Net implementation of a multiset. Can anyone recommend a good one? (A multiset, or bag, is a set that can have duplicate values, and on which you can do set operations: intersection, difference, etc. A shopping cart for instance could be thought of as a multiset because you can have multiple occurrences of the same product.)

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