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  • Python `if x is not None` or `if not x is None`?

    - by orokusaki
    I've always thought of the if not x is None version to be more clear, but Google's style guide implies (based on this excerpt) that they use if x is not None. Is there any minor performance difference (I'm assuming not), and is there any case where one really doesn't fit (making the other a clear winner for my convention)?* *I'm referring to any singleton, rather than just None. ...to compare singletons like None. Use is or is not.

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  • How to determine if CNF formula is satisfiable in Scheme?

    - by JJBIRAN
    Program a SCHEME function sat that takes one argument, a CNF formula represented as above. If we had evaluated (define cnf '((a (not b) c) (a (not b) (not d)) (b d))) then evaluating (sat cnf) would return #t, whereas (sat '((a) (not a))) would return (). You should have following two functions to work: (define comp (lambda (lit) ; This function takes a literal as argument and returns the complement literal as the returning value. Examples: (comp 'a) = (not a), and (comp '(not b)) = b. (define consistent (lambda (lit path) This function takes a literal and a list of literals as arguments, and returns #t whenever the complement of the first argument is not a member of the list represented by the 2nd argument; () otherwise. . Now for the sat function. The real searching involves the list of clauses (the CNF formula) and the path that has currently been developed. The sat function should merely invoke the real "workhorse" function, which will have 2 arguments, the current path and the clause list. In the initial call, the current path is of course empty. Hints on sat. (Ignore these at your own risk!) (define sat (lambda (clauselist) ; invoke satpath (define satpath (lambda (path clauselist) ; just returns #t or () ; base cases: ; if we're out of clauses, what then? ; if there are no literals to choose in the 1st clause, what then? ; ; then in general: ; if the 1st literal in the 1st clause is consistent with the ; current path, and if << returns #t, ; then return #t. ; ; if the 1st literal didn't work, then search << ; the CNF formula in which the 1st clause doesn't have that literal Don't make this too hard. My program is a few functions averaging about 2-8 lines each. SCHEME is consise and elegant! The following expressions may help you to test your programs. All but cnf4 are satisfiable. By including them along with your function definitions, the functions themselves are automatically tested and results displayed when the file is loaded. (define cnf1 '((a b c) (c d) (e)) ) (define cnf2 '((a c) (c))) (define cnf3 '((d e) (a))) (define cnf4 '( (a b) (a (not b)) ((not a) b) ((not a) (not b)) ) ) (define cnf5 '((d a) (d b c) ((not a) (not d)) (e (not d)) ((not b)) ((not d) (not e)))) (define cnf6 '((d a) (d b c) ((not a) (not d) (not c)) (e (not c)) ((not b)) ((not d) (not e)))) (write-string "(sat cnf1) ") (write (sat cnf1)) (newline) (write-string "(sat cnf2) ") (write (sat cnf2)) (newline) (write-string "(sat cnf3) ") (write (sat cnf3)) (newline) (write-string "(sat cnf4) ") (write (sat cnf4)) (newline) (write-string "(sat cnf5) ") (write (sat cnf5)) (newline)

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  • Rounding issue when adding floats in python, is this normal?

    - by thepearson
    I just wanted to know if this behavior is expected. If so, can someone explain to me why. This has probably been answered elsewhere I can't seem to find it using Google. Probably not searching with the right terms. I am running Ubuntu 10.04. Python 2.6.5 (r265:79063, Apr 16 2010, 13:09:56) [GCC 4.4.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> var = 10.0 >>> var 10.0 >>> var + 5 15.0 >>> var + 5.1 15.1 >>> var + 5.2 15.199999999999999 >>>

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  • Table cells with space between them

    - by Naor
    I want to make the foollowing but with CSS classes - as simple as can be: <table cellspacing="0" cellpadding="0"> <tr> <td style="color:red;text-decoration:underline;padding-right:50px;>cell1</td> <td style="color:red;text-decoration:underline;>cell2</td> </tr> <tr> <td style="color:red;text-decoration:underline;padding-right:50px;>cell3</td> <td style="color:red;text-decoration:underline;>cell4</td> </tr> </table> What is the best way to do it?

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  • C# SQL create table IF it doesn't already exist

    - by jakesankey
    Hey, I am trying to put a little logic into my C# app that will create a table called Import, IF it doesn't already exist.. here is my code, it doesn't seem to work tho. con.Open(); using (SqlCommand cmd = con.CreateCommand()) { cmd.CommandText = @" IF (EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'RX_CMMData' AND TABLE_NAME = 'Import')) BEGIN CREATE TABLE Import ( RowId integer PRIMARY KEY NOT NULL, PartNumber varchar(200) NOT NULL, CMMNumber varchar(200) NOT NULL, Date varchar(200) NOT NULL, FeatType varchar(200) NOT NULL, FeatName varchar(200) NOT NULL, Value varchar(200) NOT NULL, Actual decimal, Nominal decimal, Dev decimal, TolMin decimal, TolPlus decimal, OutOfTol decimal, FileName varchar(200) NOT NULL ); END"; cmd.ExecuteNonQuery(); } con.Close();

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  • What's the reason behind the jumping GeneratedValue(strategy=GenerationType.TABLE) when not specifyi

    - by joeduardo
    Why do I need to add allocationSize=1 when using the @TableGenerator to ensure that the id wouldn't jump from 1, 2,... to 32,xxx, 65,xxx,... after a jvm restart? Is there a design reason for the need to specify the allocationSize? This snippet would produce the jumping ids @Id @GeneratedValue(strategy = GenerationType.TABLE) private Long id; Here's the modified snippet that produces the properly sequenced ids @Id @GeneratedValue(strategy = GenerationType.TABLE, generator = "account_generator") @TableGenerator(name = "account_generator", initialValue = 1, allocationSize = 1) private Long id;

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  • Add image silverlight hovereffect from codebehind

    - by Jakob
    Hi I have a stackpanel that has a dynamic amount of images that are added programatically, Is there a way I can set a hover/click effect programatically on these images. I would like for the image to "glow" when clicked. How do i do that in silverlight? I've noticed the Image.Effect property, but I'm not really sure how to use it.

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  • Join using combined conditions on one join table

    - by Nathan Wienert
    I have join a table joining songs to genres. The table has a 'source' column that's used to identify where the genre was found. Genres are found from blogs, artists, tags, and posts. So, songs | song_genre | genres id | song_id, source, genre_id | id What I want to build is a song SELECT query that works something like this, given I already have a genre_id: IF exists song_genre with source='artist' AND a song_genre with source='blog' OR exists song_genre with source='artist' AND a song_genre with source='post' OR exists song_genre with source='tag' I'm was going to do it by doing a bunch of joins, but am sure I'm not doing it very well. Using Postgres 9.1.

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  • how to check if a data exist on a table using hibernate

    - by David
    im using hibernate with my jsp page and mySQL ,how can i do that select * from student wher userName = *** with HQL and how i chek if that username exist in 'Student' table ? in my sql i use that ResultSet resultat = statement.executeQuery(); if (resultat.next()) { ....} i try this Session hibernateSession = MyDB.HibernateUtil.currentSession(); hibernateSession.find("select xxx from Etudinat where p.Nom=xxxx"); thats give an exception so how can i do that ? i have a login form send me a username and password i want to chek if that username exist in the table Student to set the user on a session what is the safty way to do that

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  • jquery/javascript to disable button within a table cell

    - by user1831612
    I have a table cell with 2 buttons in it. <td align="left" > <input type="button" value="edit"/> <input type="button" value="save" disabled="disabled"/> </td> By default save button is disabled. On the click of edit button, save button button must be enabled. The problem is i cannot assign id's to buttons since the table is dynamically generated using struts2 s:iterator tag. If i do there will be 2 or more cells with the same id How can I achieve this?

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  • Psycopg2 doesn't like table names that start with a lower case letter

    - by Count Boxer
    I am running ActiveState's ActivePython 2.6.5.12 and PostgreSQL 9.0 Beta 1 under Windows XP. If I create a table with an upper case first letter (i.e. Books), psycopg2 returns the "Programming Error: relation "books" does not exist" error message when I run the select statement: execute("SELECT * FROM Books"). The same error is returned if I run: execute("SELECT * FROM books"). However, if I change the table to a lower case first name (i.e. books), then either of the above statements works. Are tables name supposed to have a lower case first name? Is this a setting or a feature or a bug? Am I missing something obvious?

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  • Sed substitution not doing what I want and think it should do

    - by nategoose
    I have am trying to use sed to get some info that is encoded within the path of a file which is passed as a parameter to my script (Bourne sh, if it matters). From this example path, I'd like the result to be 8 PATH=/foo/bar/baz/1-1.8/sing/song I first got the regex close by using sed as grep: echo $PATH | sed -n -e "/^.*\/1-1\.\([0-9][0-9]*\).*/p" This properly recognized the string, so I edited it to make a substitution out of it: echo $PATH | sed -n -e "s/^.*\/1-1\.\([0-9][0-9]*\).*/\1/" But this doesn't produce any output. I know I'm just not seeing something simple, but would really appreciate any ideas about what I'm doing wrong or about other ways to debug sed regular expressions.

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  • Performing Inner Join for Multiple Columns in the Same Table

    - by frankiefrank
    I have a scenario which I'm a bit stuck on. Let's say I have a survey about colors, and I have one table for the color data, and another for people's answers. tbColors color_code , color_name 1 , 'blue' 2 , 'green' 3 , 'yellow' 4 , 'red' tbAnswers answer_id , favorite_color , least_favorite_color , color_im_allergic_to 1 , 1 , 2 3 2 , 3 , 1 4 3 , 1 , 1 2 4 , 2 , 3 4 For display I want to write a SELECT that presents the answers table but using the color_name column from tbColors. I understand the "most stupid" way to do it naming tbColors three times in the FROM section, using a different alias for each column to replace. How would a non-stupid way look?

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  • MySQL temp table issue

    - by AmyD
    Hi folks! I'm trying to use temp tables to speed up my MySQL 4.1.22-standard database and what seems like a simple operation is causing me all kinds of issues. My code is below.... CREATE TEMPORARY TABLE nonDerivativeTransaction_temp (accession_number varchar(30), transactionDateValue date)) TYPE=HEAP; INSERT INTO nonDerivativeTransaction_temp VALUES( SELECT accession_number, transactionDateValue FROM nonDerivativeTransaction WHERE transactionDateValue = "2010-06-15"); SELECT * FROM nonDerivativeTransaction_temp; The original table (nonDerivativeTransaction) has two fields, accession_number (varchar(30)) and transactionDateValue (date). Apparently I am getting an issue with the first two statements but I can't seem to nail down what it is. Any help would be appreciated. Amy D.

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  • Very basic table view but getting errors

    - by user342451
    Hi guys, trying to write this code since 2 days now, but i keep getting error, it would be nice if anyone could sort this out, thanks. Basically its the same thing i doing from the tutorial on youtube. awaiting a reply // // BooksTableViewController.m // Mybooks // // #import "BooksTableViewController.h" #import "BooksDetailViewController.h" #import "MYbooksAppDelegate.h" @implementation BooksTableViewController @synthesize BooksArray; @synthesize BooksDetailViewController; /* - (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier { if ((self = [super initWithStyle:style reuseIdentifier:reuseIdentifier])) { // Initialization code } return self; } */ - (void)viewDidLoad { [super viewDidLoad]; self.title = NSLocalizedString(@"XYZ",@"GOD is GREAT"); NSMutableArray *array = [[NSArray alloc] initWithObjects:@"H1",@"2",@"3",nil]; self.booksArray = array; [array release]; } /* // Override to allow orientations other than the default portrait orientation. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } */ - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview // Release anything that's not essential, such as cached data } #pragma mark Table view methods - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } // Customize the number of rows in the table view. - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return [self.booksArray count]; } // Customize the appearance of table view cells. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *identity = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identity]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:identity] autorelease]; } // Set up the cell... cell.textLabel.text = [booksArray objectAtIndex:indexPath.row]; return cell; } /* - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { booksDetailsViewControler *NC = [[booksDetailsViewControler alloc] initWithNibName:@"BooksDetailsView" bundle:nil]; [self.navigationController pushViewController:NC animated:YES]; //[booksDetailViewController changeProductText:[booksArray objectAtIndex:indexPath.row]]; } */ NSInteger row = [indexPath row]; if (self.booksDetailViewController == nil) { BooksiDetailViewController *aCellDetails = [[AartiDetailViewController alloc] initWithNibName:@" BooksDetailViewController" bundle:nil]; self.booksDetailViewController = aCellDetails; [aCellDetails release]; } booksDetailViewController.title = [NSString stringWithFormat:@"%@", [booksArray objectAtIndex:row]]; //DailyPoojaAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; //[delegate.AartiNavController pushViewController:aartiDetailsViewControler animated:YES]; [self.navigationController pushViewController:aartiDetailViewController animated:YES]; } /* NSInteger row = [indexPath row]; if (self.booksDetailsViewControler == nil) { AartiDetailsViewControler *aBookDetail = [[BooksDetailsViewControler alloc] initWithNibName:@"booksDetaislView" bundle:nil]; self.booksDetailsViewControler = aBookDetail; [aBookDetail release]; } booksDetailsViewControler.title = [NSString stringWithFormat:@"%@", [booksArray objectAtIndex:row]]; [self.navigationController pushViewController:booksDetailsViewControler animated:YES]; */ - (void)dealloc { [aartiDetailViewController release]; [super dealloc]; } @end

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  • select row from table and substitute a field with one from another column if it exists

    - by EarthMind
    I'm trying construct a PostgreSQL query that does the following but so far my efforts have been in vain. Problem: There are two tables: A and B. I'd like to select all columns from table A (having columns: id, name, description) and substitute the "A.name" column with the value of the column "B.title" from table B (having columns: id, table_A_id title, langcode) where B.table_A_id is 5 and B.langcode is "nl" (if there are any rows). My attempts: SELECT A.name, case when exists(select title from B where table_A_id = 5 and langcode= 'nl') then B.title else A.name END FROM A, B WHERE A.id = 5 and B.table_A_id = 5 and B.langcode = 'nl' -- second try: SELECT COALESCE(B.title, A.name) as name from A, B where A.id = 5 and B.table_A_id = 5 and exists(select title from B where table_A_id = 5 and langcode= 'nl') I've tried using a CASE and COALESCE() but failed due to my inexperience with both concepts. Thanks in advance.

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  • What is the role of `while`-loops in computation expressions in F#?

    - by MizardX
    If you define a While method of the builder-object, you can use while-loops in your computation expressions. The signature of the While method is: member b.While (predicate:unit->bool, body:M<'a>) : M<'a> For comparison, the signature of the For method is: member b.For (items:seq<'a>, body:unit->M<'a>) : M<'a> You should notice that, in the While-method, the body is a simple type, and not a function as in the For method. You can embed some other statements, like let and function-calls inside your computation-expressions, but those can impossibly execute in a while-loop more than once. builder { while foo() do printfn "step" yield bar() } Why is the while-loop not executed more than once, but merely repeated? Why the significant difference from for-loops? Better yet, is there some intended strategy for using while-loops in computation-expressions?

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  • jquery - clone nth row of a table?

    - by John
    I'm trying to use jquery to clone a table row everytime someone presses the add-row button. Can anyone tell me what's wrong with my code? I'm using HTML + smarty templating language in my view. Here's what my template file looks like: <table> <tr> <td>Description</td> <td>Unit</td> <td>Qty</td> <td>Total</td> <td></td> </tr> <tbody id="entries"> {foreach from=$arrItem item=i name=inv} <tr> <td> <input type="hidden" name="invoice_item_id[]" value="{$i.invoice_item_id}"/> <input type="hidden" name="assignment_id[]" value="{$i.assignment_id}" /> <input type="text" name="description[]" value="{$i.description}"/> </td> <td><input type="text" class="unit_cost" name="unit_cost[]" value="{$i.unit_cost}"/></td> <td><input type="text" class="qty" name="qty[]" value="{$i.qty}"/></td> <td><input type="text" class="cost" name="cost[]" value="{$i.cost}"/></td> <td><a href="javascript:void(0);" class="delete-invoice-item">delete</a></td> </tr> {/foreach} </tbody> <tfoot> <tr><td colspan="5"><input type="button" id="add-row" value="add row" /></td></tr> </tfoot> </table> Here's my Jquery Javascript call, which I know gets fired when I put in an alert() statement. So the problem is with me not knowing how jquery works. $('#add-row').live('click', function() {$('#entries tr:nth-child(0)').clone().appendTo('#entries');}); So what am I doing wrong?

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  • populating html table from database

    - by kawtousse
    Hi everyone, I want to generate html table in my jsp witch display values selected before submitting to allow user to know what did he puts into the form. So I finish the form when submitting the values are inserted in database. Now I search the possibility to display in the same jsp of the form the table having all the values selected. So it is possible ton allow to actions in the form tag to insert and display from database at the same time. Many Thanks for your help.

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  • Informix - Fetching Records from a table

    - by Pradeep
    Consider the below table Col1 Col2 Col3 123 ABC 20/5/2010 123 CDS 21/5/2010 123 VDS 22/5/2010 123 ABC 23/5/2010 123 VDS 24/5/2010 123 CDS 25/5/2010 123 ABC 26/5/2010 I need to fetch the first occurrence of CDS and calculate the time diff between the next row. Similarly I need to find out the next occurrence of CDS and calculate the time diff with the next row. This has to go on until there are no occurrences of CDS left in the table. Will be grateful if someone can help on this!!

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  • c# .net MVC4 Model to represent table or form

    - by Matthew Chambers
    Hello I am a little confused with regards to models in mvc 4 and thought someone may be able to point me in the right direction. This would be most appreciated. For example if i have a table that has the following fields [StringLength(100, ErrorMessage = "The {0} must be at least {2} characters long.", MinimumLength = 5)] public string UserName { get; set; } [Required(ErrorMessage="Email Address is Required")] [StringLength(15, ErrorMessage = "Email Address must be between {0} and {1} in size",MinimumLength = 5 )] [DataType(DataType.EmailAddress)] [Display(Name="Email")] public string Email { get; set; } [MaxLength(25)] [Display(Name="Mobile Telephone Number")] public string Mobile {get;set;} [MaxLength(500)] [Display(Name="Headline")] public string Headline {get;set;} [Required] [StringLength(200)] [Display(Name = "First Name")] public string FirstName {get;set;} [Required] [StringLength(200)] [Display(Name="Surname")] public string Surname { get; set;} public virtual int? DayOfBirthId { get; set; } public virtual DayOfBirth DayOfBirth { get; set; } public virtual int? MonthOfBirthId { get; set; } public virtual MonthOfBirth MonthOfBirth { get; set; } public virtual int? YearOfBirthId { get; set; } public virtual YearOfBirth YearOfBirth{get;set;} This is my user profile table in the database. However I would like a form that the user registers to the site with. When they first register i do not need all the details such as telephone all i really need is there username, email address and password. Do i create another model for this. Or do i have one model and on the controller set the fields to null or empty string that are not required on registration. I have validation also so would this be set for data that has not been entered on the form. My question is ultimately should all forms represent models- should the database be redesigned to meet this required. Or should the controller set the values that are not required. Or should there be another model that represents the form be created which maps to this table. I am a little confused on this and clarification of anyone would be most appreciated.

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  • Not unique table/alias - can't understand why!?

    - by Andy Barlow
    Hi! I'm trying to join some tables together in MySQL, but I seem to get an error saying: #1066 - Not unique table/alias: 'calendar_jobs' I really want it to select everything from the cal_events, the 2 user bits and just the destination col from the jobs table, but become "null" if there arn't any job. A right join seemed to fit the bill but doesn't work! Can anyone help!? SELECT calendar_events.* , calendar_users.doctorOrNurse, calendar_users.passportName, calendar_jobs.destination FROM `calendar_events` , `calendar_users` , `calendar_jobs` RIGHT JOIN calendar_jobs ON calendar_events.jobID = calendar_jobs.jobID WHERE `start` >=0 AND calendar_users.userID = calendar_events.userID Cheers!

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