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• postgres counting one record twice if it meets certain criteria

  - by Dashiell0415

  I thought that the query below would naturally do what I explain, but apparently not... My table looks like this: id | name | g | partner | g2 1 | John | M | Sam | M 2 | Devon | M | Mike | M 3 | Kurt | M | Susan | F 4 | Stacy | F | Bob | M 5 | Rosa | F | Rita | F I'm trying to get the id where either the g or g2 value equals 'M'... But, a record where both the g and g2 values are 'M' should return two lines, not 1. So, in the above sample data, I'm trying to return: $q = pg_query("SELECT id FROM mytable WHERE ( g = 'M' OR g2 = 'M' )"); 1 1 2 2 3 4 But, it always returns: 1 2 3 4

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• jQuery remove selected option from this

  - by odavy

  Hi all, first post here, I come in peace :) I've searched but can't quite find what I'm after. I am trying to manipulate the selected option of a select box. Can someone please explain why this works: $('#some_select_box').click(function() { $('#some_select_box option:selected').remove(); }); but this doesn't: $('#some_select_box').click(function() { $('this option:selected').remove(); }); I just want to use "this" instead of spelling out the id of the select box - can someone point me in the right direction for the correct syntax? It's driving me mad because it looks like it should be really simple. And I'm sure it is to someone, but not me, cos its the end of the day and I'm brain-fried... Any pointers much appreciated. Cheers

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• Weird SQL Server 2005 Collation difference between varchar() and nvarchar()

  - by richardtallent

  Can someone please explain this: SELECT CASE WHEN CAST('iX' AS nvarchar(20)) > CAST('-X' AS nvarchar(20)) THEN 1 ELSE 0 END, CASE WHEN CAST('iX' AS varchar(20)) > CAST('-X' AS varchar(20)) THEN 1 ELSE 0 END Results: 0 1 SELECT CASE WHEN CAST('i' AS nvarchar(20)) > CAST('-' AS nvarchar(20)) THEN 1 ELSE 0 END, CASE WHEN CAST('i' AS varchar(20)) > CAST('-' AS varchar(20)) THEN 1 ELSE 0 END Results: 1 1 On the first query, the nvarchar() result is not what I'm expecting, and yet removing the X make the nvarchar() sort happen as expected. (My original queries used the '' and N'' literal syntax to distinguish varchar() and nvarchar() rather than CAST() and got the same result.) Collation setting for the database is SQL_Latin1_General_CP1_CI_AS.

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• Geocoding non-addresses: Geopy

  - by Phil Donovan

  Using geopy to geocode alcohol outlets in NZ. The problem I have is that some places do not have street addresses but are places in Google Maps. For example, plugging: Furneaux Lodge, Endeavour Inlet, Queen Charlotte Sound, Marlborough 7250 into Google Maps via the browser GUI gives me However, using that in Geopy I get a GQueryError saying this geographic location does not exist. Here is the code for geocoding: def GeoCode(address): g=geocoders.Google(domain="maps.google.co.nz") geoloc = g.geocode(address, exactly_one=False) place, (lat, lng) = geoloc[0] GeoOut = [] GeoOut.extend([place, lat, lng]) return GeoOut GeoCode("Furneaux Lodge, Endeavour Inlet, Queen Charlotte Sound, Marlboroguh 7250") Meanwhile, I notice that "Eiffel Tower" works fine. Is there away to solve this and can someone explain the difference between The Eiffel Tower and Furneaux Lodge within Google 'locations'?

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• LINQ: why does this query not work on an ArrayList?

  - by Benny

  public static ArrayList GetStudentAsArrayList() { ArrayList students = new ArrayList { new Student() { RollNumber = 1,Name ="Alex " , Section = 1 ,HostelNumber=1 }, new Student() { RollNumber = 2,Name ="Jonty " , Section = 2 ,HostelNumber=2 } }; return students; } The following code doesn't compile. The error is ArrayList is not IEnumerable ArrayList lstStudents = GetStudentAsArrayList(); var res = from r in lstStudents select r; This compiles: ArrayList lstStudents = GetStudentAsArrayList(); var res = from Student r in lstStudents select r; Can anybody explain what the difference is between these two snippets? Why the second works?

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• Prototype mouseleave for two connected elements

  - by TenJack

  I have created a small navigation element that is positioned right on top of another element. It is only shown when a user mousenters/mouseovers the main element. I am having some trouble with the prototype. I would like this small nav element to be hidden when a user mouses out of the main box, but I would also like the small nav element to remain visible if a user mouses out of the main box but mouses into the small nav at the same time. This is my attempt so far with some pseudo-code to hopefully explain: $('main_box').observe('mouseenter', function(){ $('small_div').show() }) $('main_box').observe('mouseleave', function(){ if this element is $('small_div') then Event.stop() $('small_div').observe('mouseleave', function(){ if this element is $('main_box') Event.stop observe $('main_box') mouseleave else $('small_div').hide(); }) else $('small_div').hide(); }) The main thing I'm having trouble with is figuring out what element the mouse is over at a given point in time. Is there a way to do something like: on mouseleave do blah unless the mouse is over a specific element then do not do blah?

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• Inheriting and static members

  - by Bruce

  Here is my code - #include <iostream> #include <conio.h> using namespace std; class Base { public: int a; }; //int Base::a = 5; class Derived : public Base { public: int static a; }; int main() { Derived d; cout<<d.a; getch(); return 0; } I get a linker error here. But when I do it the other way round - class Base { public: int static a; }; int Base::a = 5; class Derived : public Base { public: int a; }; I get no error. Can someone please explain what is happening here.

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• Having an online highscore leaderboard for a Flash game

  - by Marco Fox

  Why, hello there. I'm trying to develop a simple Flash game using Actionscript 2 (I know its a bit dated, but its a simple project that doesen't benefict much from AS3), and I came up with an ideia of implementing an online leaderboard that records and shows the highscore of the player. This isn't anything too complicated, but I seem to be having problem finding resources online that explain how I should implement this. All I want is a call, probably to a PHP/MySQL database that records the player's name (which will be recorded via a input window) and its current score. It would also have to show the best all time scores, by order. I should remind you that I am working on a Actionscript 2 so Actionscript 3 solutions are probably not going to work. Can anyone out there help me out here? Did any of you already been through this?

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• [C#] Async threaded tcp server

  - by mark_dj

  I want to create a high performance server in C# which could take about ~10k clients. Now i started writing a TcpServer with C# and for each client-connection i open a new thread. I also use one thread to accept the connections. So far so good, works fine. The server has to deserialize AMF incoming objects do some logic ( like saving the position of a player ) and send some object back ( serializing objects ). I am not worried about the serializing/deserializing part atm. My main concern is that I will have a lot of threads with 10k clients and i've read somewhere that an OS can only hold like a few hunderd threads. Are there any sources/articles available on writing a decent async threaded server ? Are there other possibilties or will 10k threads work fine ? I've looked on google, but i couldn't find much info about design patterns or ways which explain it clearly

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• Perl Hash Slice, Replication x Operator, and sub params

  - by user210757

  Ok, I understand perl hash slices, and the "x" operator in Perl, but can someone explain the following code example from here (slightly simplified)? sub test{ my %hash; @hash{@_} = (undef) x @_; } Example Call to sub: test('one', 'two', 'three'); This line is what throws me: @hash{@_} = (undef) x @_; It is creating a hash where the keys are the parameters to the sub and initializing to undef, so: %hash: 'one' = undef, 'two' = undef, 'three' = undef The rvalue of the x operator should be a number; how is it that @_ is interpreted as the length of the sub's parameter array? I would expect you'd at least have to do this: @hash{@_} = (undef) x length(@_);

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• Haskell: What is the difference between $ (dollar) and $! (dollar exclamation point)

  - by Jelle Fresen

  Can anybody explain the difference in Haskell between the operators ($) and ($!) (dollar sign vs dollar sign exclamation point)? I haven't seen the use of $! anywhere so far, but while browsing through the Haskell reference on www.zvon.org, I noticed its existence and that it has the exact same definition as $. When trying some simple statements in a Haskell interpreter (ghci), I couldn't find any difference, nor could I find any reference to the operator in the top listed tutorials when googling for haskell tutorial. So, just out of curiosity, what is the difference, if at all?

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• Single HTML Table from multiple MySQL tables

  - by David Chouinard

  Hi! I've been struggling for a while with this one; I'll try to explain it here as simply as possible. Consider this MySQL table: +----------+-----------+---------+--------+ |status_id |session_id |pilot_id |present | +----------+-----------+---------+--------+ |1 |61 |901 |1 | |2 |63 |901 |1 | |3 |62 |901 |0 | |4 |62 |902 |1 | |5 |63 |903 |1 | +----------+-----------+---------+--------+ Both session_id and pilot_id are foreign keys making reference to a primary key in another table. The same pilot_id can be associated with different session_id, but every pilot_id-session_id combination is unique. I need to make an HTML table (in PHP) that would display the data like this: +----------+---------+---------+---------+ | |61 |62 |63 | +----------+---------+---------+---------+ |901 |X | |X | |902 | |X | | |903 | | |X | +----------+---------+---------+---------+ Hence, rows are pilot_id and columns are session_id. When a pilot_id-session_id combination has a present value of 1, the corresponding cell should be checked. (ie. when the row-combination is zero or the combination does not exist in the MySQL table, nothing should appear in the HTML table) Phew. Any ideas? Thanks!

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• GLOBAL problem with javascript

  - by Syom

  There is some problem, i can't understand anyway. look at this code please <script type="text/javascript"> function math(x) { var y; y = x*10; alert(y); } </script> <input type="button" onclick="math(0.011)"> What must be alerted after i click on button? i think 0.11, but no, it alerts 0.10999999999999999 explain please this behavior. thanks in advance

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• Why are the contents of my UITableViewCell disappearing?

  - by barfoon

  Hey everyone, I am learning about using the checkmark cell accessory and am wondering why the contents of my cell is disappearing when toggling it. Here is my code: + (void) toggleCheckmarkedCell:(UITableViewCell *)cell { if (cell.accessoryType == UITableViewCellAccessoryNone) cell.accessoryType = UITableViewCellAccessoryCheckmark; else cell.accessoryType = UITableViewCellAccessoryNone; } And here is didSelectRowAtIndexPath: UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath]; [cell setSelectionStyle:UITableViewCellSelectionStyleNone]; [RootViewController toggleCheckmarkedCell:cell]; The checkmark is toggling on/off and is visible but the main contents of the cell disappears. Can anyone explain why this is happening? Thank you,

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• How to optimise MySQL query containing a subquery?

  - by aidan

  I have two tables, House and Person. For any row in House, there can be 0, 1 or many corresponding rows in Person. But, of those people, a maximum of one will have a status of "ACTIVE", the others will all have a status of "CANCELLED". e.g. SELECT * FROM House LEFT JOIN Person ON House.ID = Person.HouseID House.ID | Person.ID | Person.Status 1 | 1 | CANCELLED 1 | 2 | CANCELLED 1 | 3 | ACTIVE 2 | 1 | ACTIVE 3 | NULL | NULL 4 | 4 | CANCELLED I want to filter out the cancelled rows, and get something like this: House.ID | Person.ID | Person.Status 1 | 3 | ACTIVE 2 | 1 | ACTIVE 3 | NULL | NULL 4 | NULL | NULL I've achieved this with the following sub select: SELECT * FROM House LEFT JOIN ( SELECT * FROM Person WHERE Person.Status != "CANCELLED" ) Person ON House.ID = Person.HouseID ...which works, but breaks all the indexes. Is there a better solution that doesn't? I'm using MySQL and all relevant columns are indexed. EXPLAIN lists nothing in possible_keys. Thanks.

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• How can i have a div stuck on the left side of the page no matter how much i scroll horizontally?

  - by Noor

  This is kind of difficult to explain so ill link to a page that has the effect i need; http://wpaoli.building58.com/wp-content/uploads/2009/08/feedback-panel.html The feedback thing on the left side is what im trying to implement on my side, instead of feedback im going to use it as a navigation menu that shows up when clicked on. the things above is what i have right now. my problem is when i scroll to the right ( my page is around 6000px wide ) i want it to stay on the left side, is there a way to pull this off? (this is to much for my brain to handle)..thanks!

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• what is the idea behind scaling an image using lanczos?

  - by banister

  Hi, I'm interested in image scaling algorithms and have implemented the bilinear and bicubic methods. However, I have heard of the lanczos and other more sophisticated methods for even higher quality image scaling and I am very curious how they work. Could someone here explain the basic idea behind scaling an image using lanczos (both upscaling and downscaling) and why it results in higher quality? I do have a background in fourier analysis and have done some signal processing stuff in the past, but not with relation to image processing, so don't be afraid to use terms like "frequency response" and such in your answer :) EDIT: I guess what i really want to know is the concept and theory behind using a convolution filter for interpolation. (Note: i have already read the wikipedia article on lanczos resampling but it didn't have nearly enough detail for me) thanks alot!

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• TypeError: Python thinks that I passed a function 2 arguments but I only passed it 1

  - by slhck

  I work on something in Seattle Repy which is a restricted subset of Python. Anyway, I wanted to implement my own Queue that derives from a list: class Queue(list): job_count = 0 def __init__(self): list.__init__(self) def appendleft(item): item.creation_time = getruntime() item.current_count = self.job_count self.insert(0, item) def pop(): item = self.pop() item.pop_time = getruntime() return item Now I call this in my main server, where I use my own Job class to pass Jobs to the Queue: mycontext['queue'] = Queue() # ... job = Job(str(ip), message) mycontext['queue'].appendleft(job) The last line raises the following exception: Exception (with type 'exceptions.TypeError'): appendleft() takes exactly 1 argument (2 given) I'm relatively new to Python, so could anyone explain to me why it would think that I gave appendleft() two arguments when there obviously was only one?

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• 2-Version software: Best VCS approach?

  - by Tom R

  I suppose I'd better explain my situation: I'm in the process of developing some software, and I'm at the stage where I'd like to split my project into two branches which differ in features. It so happens that this application is an Android application which I will be deploying on the Market, which has the constraint that every app must have a unique package identifier (sensible, no?). My current approach has been to clone the git repo of my original project, but this causes issues with package names. I want the system to be robust enough so that a bugfix/new feature on one branch will merge into another branch, but only when I want it to. Does anyone have any suggestions?

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• tomcat 6 - Cluster / BackupManager

  - by Kevin

  Hi, I have a question regarding Clustering (session replication/failover) in tomcat 6 using BackupManager. Reason I chose BackupManager, is because it replicates the session to only one other server. I am going to run through the example below to try and explain my question. I have 6 nodes setup in a tomcat 6 cluster with BackupManager. The front end is one Apache server using mod_jk with sticky session enabled Each node has 1 session each. node1 has a session from client1 node2 has a session from client2 .. .. Now lets say node1 goes down ; assuming node2 is the backup, node2 now has two sessions (for client2 and client1) The next time client1 makes a request, what exactly happens ? Does Apache "know" that node1 is down and does it send the request directly to node2 ? =OR= does it try each of the 6 instances and find out the hard way who the backup is ?

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• Service design or access to another process

  - by hotyi

  I have a cache service,it's works as .net remoting, i want to create another windows service to clean up the that cache service by transfer the objects from cache to files. because they are in separate process, is their any way i could access that cache service or do i have to expose a method from the cache service to do that clean up work? the "clean up" means i want to serialize the object from Cache to file and these saved file will be used for further process. let me explain this application more detail. the application is mainly a log service to log all the coming request and these request will be saved to db for further data mining. we have 2 design for this log system 1) use MSMQ, but seems it's performance is not good enough, we don't use it. 2) we design a cache service, each request will be saved into the cache, and we need another function to clean up the cache by serialize the object to file.

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• Python sys.argv lists and indexes

  - by Fred Gerbig

  In the below code I understand that sys.argv uses lists, however I am not clear on how the index's are used here. def main(): if len(sys.argv) >= 2: name = sys.argv[1] else: name = 'World' print 'Hello', name if __name__ == '__main__': main() If I change name = sys.argv[1] to name = sys.argv[0] and type something for an argument it returns: Hello C:\Documents and Settings\fred\My Documents\Downloads\google-python-exercises \google-python-exercises\hello.py Which kind of make sense. Can someone explain how the 2 is used here: if len(sys.argv) >= 2: And how the 1 is used here: name = sys.argv[1]

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• Python Imaging: YCbCr problems

  - by daver

  Hi, I'm doing some image processing in Python using PIL, I need to extract the luminance layer from a series of images, and do some processing on that using numpy, then put the edited luminance layer back into the image and save it. The problem is, I can't seem to get any meaningful representation of my Image in a YCbCr format, or at least I don't understand what PIL is giving me in YCbCr. PIL documentation claims YCbCr format gives three channels, but when I grab the data out of the image using np.asarray, I get 4 channels. Ok, so I figure one must be alpha. Here is some code I'm using to test this process: import Image as im import numpy as np pengIm = im.open("Data\\Test\\Penguins.bmp") yIm = pengIm.convert("YCbCr") testIm = np.asarray(yIm) grey = testIm[:,:,0] grey = grey.astype('uint8') greyIm = im.fromarray(grey, "L") greyIm.save("Data\\Test\\grey.bmp") I'm expecting a greyscale version of my image, but what I get is this jumbled up mess: http://i.imgur.com/zlhIh.png Can anybody explain to me where I'm going wrong? The same code in matlab works exactly as I expect.

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• Does mod_rewrite in subdirectories' .htaccess override higher levels?

  - by Ryan

  I'm using mod_rewrite to map my old directory structure to a new one. I have the following rule in my top-level .htaccess file, and it works: RewriteEngine On RewriteCond %{REQUEST_URI} /blog/archives/(.*) RewriteRule ^.*$ /archives/%1 [L,R=301] As you can guess, this takes http://example.com/blog/archives/00001.php and redirects it to http://example.com/archives/00001.php. But when I add these rewrite rules to the .htaccess file in the /blog directory RewriteEngine on RewriteRule atom.xml$ /atom.xml [L,R=301] the top-level redirect no longer works. If I move the rule in the /blog .htaccess file to the top-levle file both rules work. Can someone explain what is happening here?

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• Why is the destructor called when the CPython garbage collector is disabled?

  - by Frederik

  I'm trying to understand the internals of the CPython garbage collector, specifically when the destructor is called. So far, the behavior is intuitive, but the following case trips me up: Disable the GC. Create an object, then remove a reference to it. The object is destroyed and the __del__ method is called. I thought this would only happen if the garbage collector was enabled. Can someone explain why this happens? Is there a way to defer calling the destructor? import gc import unittest _destroyed = False class MyClass(object): def __del__(self): global _destroyed _destroyed = True class GarbageCollectionTest(unittest.TestCase): def testExplicitGarbageCollection(self): gc.disable() ref = MyClass() ref = None # The next test fails. # The object is automatically destroyed even with the collector turned off. self.assertFalse(_destroyed) gc.collect() self.assertTrue(_destroyed) if __name__=='__main__': unittest.main() Disclaimer: this code is not meant for production -- I've already noted that this is very implementation-specific and does not work on Jython.

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