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  • Exit Tks mainloop in Python?

    - by Olof
    I'm writing a slideshow program with Tkinter, but I don't know how to go to the next image without binding a key. import os, sys import Tkinter import Image, ImageTk import time root = Tkinter.Tk() w, h = root.winfo_screenwidth(), root.winfo_screenheight() root.overrideredirect(1) root.geometry("%dx%d+0+0" % (w, h)) root.focus_set() root.bind("<Escape>", lambda e: e.widget.quit()) image_path = os.path.join(os.getcwd(), 'images/') dirlist = os.listdir(image_path) for f in dirlist: try: image = Image.open(image_path+f) tkpi = ImageTk.PhotoImage(image) label_image = Tkinter.Label(root, image=tkpi) # ? label_image.place(x=0,y=0,width=w,height=h) root.mainloop(0) except IOError: pass root.destroy() I would like to add a time.sleep(10) "instead" of the root.mainloop(0) so that it would go to the next image after 10s. Now it changes when I press ESC. How can I have a timer there?

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  • Fast iterating over first n items of an iterable (not a list) in python

    - by martinthenext
    Hello! I'm looking for a pythonic way of iterating over first n items of an iterable (upd: not a list in a common case, as for lists things are trivial), and it's quite important to do this as fast as possible. This is how I do it now: count = 0 for item in iterable: do_something(item) count += 1 if count >= n: break Doesn't seem neat to me. Another way of doing this is: for item in itertools.islice(iterable, n): do_something(item) This looks good, the question is it fast enough to use with some generator(s)? For example: pair_generator = lambda iterable: itertools.izip(*[iter(iterable)]*2) for item in itertools.islice(pair_generator(iterable), n): so_something(item) Will it run fast enough as compared to the first method? Is there some easier way to do it?

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  • LINQ Expression<Func<T, bool>> equavalent of .Contains()

    - by BK
    Has anybody got an idea of how to create a .Contains(string) function using Linq Expressions, or even create a predicate to accomplish this public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expr1, Expression<Func<T, bool>> expr2) { var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>()); return Expression.Lambda<Func<T, bool>> (Expression.OrElse(expr1.Body, invokedExpr), expr1.Parameters); } Something simular to this would be ideal?

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  • Functional languages targeting the LLVM

    - by Matthew
    Are there any languages that target the LLVM that: Are statically typed Use type inference Are functional (i.e. lambda expressions, closures, list primitives, list comprehensions, etc.) Have first class object-oriented features (inheritance, polymorphism, mixins, etc.) Have a sophisticated type system (generics, covariance and contravariance, etc.) Scala is all of these, but only targets the JVM. F# (and to some extent C#) is most if not all of these, but only targets .NET. What similar language targets the LLVM?

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  • Python/PyParsing: Difficulty with setResultsName

    - by Rosarch
    I think I'm making a mistake in how I call setResultsName(): from pyparsing import * DEPT_CODE = Regex(r'[A-Z]{2,}').setResultsName("Dept Code") COURSE_NUMBER = Regex(r'[0-9]{4}').setResultsName("Course Number") COURSE_NUMBER.setParseAction(lambda s, l, toks : int(toks[0])) course = DEPT_CODE + COURSE_NUMBER course.setResultsName("course") statement = course From IDLE: >>> myparser import * >>> statement.parseString("CS 2110") (['CS', 2110], {'Dept Code': [('CS', 0)], 'Course Number': [(2110, 1)]}) The output I hope for: >>> myparser import * >>> statement.parseString("CS 2110") (['CS', 2110], {'Course': ['CS', 2110], 'Dept Code': [('CS', 0)], 'Course Number': [(2110, 1)]}) Does setResultsName() only work for terminals?

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  • Expression Tree : C#

    - by nettguy
    My understanding of expression tree is : Expression trees are in-memory representation of expression like arithmetic or boolean expression.The expressions are stored into the parsed tree.so we can easily transalate into any other language. Linq to SQL uses expression tree.Normally when our LINQ to SQL query compiler translates it to parsed expression trees.These are passed to Sql Server as T-SQL Statements.The Sql server executes the T-SQL query and sends down the result back.That is why when you execute LINQ to SQL you gets IQueryable<T> not IEnumetrable<T>.Because IQuerybale contains public IQueryable:IEnumerable { Type Element {get;} Expression Expression {get;} IQueryaleProvider Provider {get;} } Questions : Microsoft uses Expression trees to play with LINQ-to-Sql.What are the different ways can i use expression trees to boost my code. Apart from LINQ to SQL,Linq to amazon ,who used expression trees in their applications? Linq to Object return IEnumerable,Linq to SQL return IQueryable ,What does LINQ to XML return?

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  • how to format date when i load data from google-app-engine..

    - by zjm1126
    i use remote_api to load data from google-app-engine. appcfg.py download_data --config_file=helloworld/GreetingLoad.py --filename=a.csv --kind=Greeting helloworld the setting is: class AlbumExporter(bulkloader.Exporter): def __init__(self): bulkloader.Exporter.__init__(self, 'Greeting', [('author', str, None), ('content', str, None), ('date', str, None), ]) exporters = [AlbumExporter] and i download a.csv is : the date is not readable , and the date in appspot.com admin is : so how to get the full date ?? thanks i change this : class AlbumExporter(bulkloader.Exporter): def __init__(self): bulkloader.Exporter.__init__(self, 'Greeting', [('author', str, None), ('content', str, None), ('date', lambda x: datetime.datetime.strptime(x, '%m/%d/%Y').date(), None), ]) exporters = [AlbumExporter] but the error is :

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  • named_scope and substings

    - by Philb28
    I have a named_scope in rails that finds episodes by there directors given name named_scope :director_given, lambda { |dr| {:joins => :director, :conditions => ['given = ?', dr]} } It works great but I would like it to also work on substrings one the name. e.g. instead of having to search for 'Lucy' you could just search 'Lu'. P.S. I also have another named scope which does exactly the same thing but on the directors last name. It there a way to combine the two? Thanks,

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  • declarative authorization and has_and_belongs_to_many

    - by Michael Balsiger
    Hi, I have a little problem with declarative-authorization. I have a User and Role Model with a has_and_belongs_to_many association. I've created a Role named :moderator in my authorization_rules.rb Is it possible that a User with the Role Moderator only gets the Users that have the Moderator Role assigned to it?? -- User.with_permissions_to(:index) I thought it would be possible like that: role :moderator do has_permission_on :users, :to => :index do if_attribute :roles => contains { ????? } end end I also created a named_scope in my User Model because I thought it would help... class User has_and_belongs_to_many :roles named_scope :by_role, lambda { |role| { :include => :roles, :conditions => {"roles.name" => role} } } end Does anyone knows if it's possible to do this with declarative_authorization? Thanks for your help!

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  • Do I need to include the 'this' when using a property name in a closure?

    - by Scott Whitlock
    I'm using a list of Actions to store an undo history for an object. Let's say I have a property of my object called myChildObject and it's being changed, so I want to store the undo action where I would set it back to it's current value: public class Class1 { public Class1() { } private readonly List<Action> m_undoActions = new List<Action>(); private SomeObject myChildObject { get; set; } public void ChangeState(SomeObject newChildObject) { // copies the reference SomeObject existingObject = myChildObject; m_undoActions.Add(() => myChildObject = existingObject); myChildObject = newChildObject; } } Looking at the lambda expression, existingObject is a local variable, so it's using a closure to pass a reference to that variable, but what about the property myChildObject? Do I need to use 'this' to preface it? Do I need to make a copy of the 'this' reference to a local variable first? Thanks for helping me understand this closure stuff.

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  • Container of shared_ptr's but iterate with raw pointers

    - by Sean Lynch
    I have a class that holds a list containing boost::shared_ptrs to objects of another class. The class member functions that give access to the elemets in the list return raw pointers. For consistency I'd also like to be able to iterate with raw pointers instead of shared_ptrs. So when I dereference the list iterator, I'd like to get raw pointer, not a shared_ptr. I assume I need to write a custom iterator for this. Is this correct? If so can someone point me in the right direction - I've never done this before.

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  • Is there a standard Cyclic Iterator in C++

    - by Hippicoder
    Based on the following question: Check if one string is a rotation of other string I was thinking of making a cyclic iterator type that takes a range, and would be able to solve the above problem like so: std::string s1 = "abc" ; std::string s2 = "bca" ; std::size_t n = 2; // number of cycles cyclic_iterator it(s2.begin(),s2.end(),n); cyclic_iterator end; if (std::search(it, end, s1.begin(),s1.end()) != end) { std::cout << "s1 is a rotation of s2" << std::endl; } My question, Is there already something like this available? I've check Boost and STL doesn't have one. I've got a simple hand-written one but would rather use an already made/tested implementation.

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  • Python How to make a cross-module function?

    - by Evan
    I want to be able to call a global function from an imported class, for example In file PetStore.py class AnimalSound(object): def __init__(self): if 'makenoise' in globals(): self.makenoise = globals()['makenoise'] else: self.makenoise = lambda: 'meow' def __str__(self): return self.makenoise() Then when I test in the Python Interpreter >>> def makenoise(): ... return 'bark' ... >>> from PetStore import AnimalSound >>> sound = AnimalSound() >>> sound.makenoise() 'meow' I get a 'meow' instead of 'bark'. I have tried using the solutions provided in python-how-to-make-a-cross-module-variable with no luck.

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  • Why wont numpy matrix let me print its rows?

    - by uberjumper
    Okay this is probably a really dumb question, however its really starting to hurt. I have a numpy matrix, and basically i print it out row by row. However i want to make each row be formatted and separated properly. >>> arr = numpy.matrix([[x for x in range(5)] for y in range(5)]) >>> arr matrix([[0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4]]) Lets say i want to print the first row, and add a '|' between each element: >>> '|'.join(map(str, arr[0,])) '[[0 1 2 3 4]]' Err... >>> '|'.join(map(lambda x: str(x[0]), arr[0])) '[[0 1 2 3 4]]' I am really confused by this behavior why does it do this?

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  • std::for_each on a member function with 1 argument

    - by Person
    I'm wondering how to implement what is stated in the title. I've tried something like... std::for_each( a.begin(), a.end(), std::mem_fun_ref( &myClass::someFunc ) ) but I get an error saying that the "term" (I"m assuming it means the 3rd argument) doesn't evaluate to a function with 1 argument, even though someFunc does take one argument - the type of the objects stored in a. I'm wondering if what I'm trying to do is possible using the standard library (I know I can do it easily using boost). P.S. Does using for_each and mem_fun_ref have any performance implications in comparison to just iterating through a manually and passing the object to someFunc?

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  • Easy way to parse a url in C++ cross platform?

    - by Andrew Bucknell
    I need to parse a url to get the protocol host path and query in an application I am writing in c++. The application is intended to be cross platform. Im surprised I cant find anything that does this in boost or poco libraries. Is it somewhere obvious Im not looking? Any suggestions on appropriate open source libs? Or is this something I just have to do my self? Its not super complicated but it seems such a common task I am surprised there isnt a common solution.

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  • Why would the assignment operator ever do something different than its matching constructor?

    - by Neil G
    I was reading some boost code, and came across this: inline sparse_vector &assign_temporary(sparse_vector &v) { swap(v); return *this; } template<class AE> inline sparse_vector &operator=(const sparse_vector<AE> &ae) { self_type temporary(ae); return assign_temporary(temporary); } It seems to be mapping all of the constructors to assignment operators. Great. But why did C++ ever opt to make them do different things? All I can think of is scoped_ptr?

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  • Database caching on a shared host

    - by tau
    Anyone have any ideas how to increase MySQL performance on a shared host? My question has less to do with overall database performance and more to do with simply retrieving user-submitted data. Currently my database will create caches at timed intervals, and then the PHP will selectively access the static files it needs. This has given me a noticeable performance boost, but I am worried about a time in which I have so much data that having to read in big files in PHP will actually be slower. I am just looking for ideas for shared hosting solutions; I am not going to get my own server anytime soon. Thanks!

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  • Per query relevance elevation for solr?

    - by plusplus
    I want to tune the relevance of solr search results on a per user basis - based on the number of times the user has clicked through a result before. Frequently hit items FOR THAT USER should rise to the top of their search results. Is there a way to provide custom boost/elevation for particular document ids on the query? I'm thinking in the order of ~100s of particular documents to elevate. The elevation should have no effect if the rest of the query doesn't find those documents. Alternatively, if this isn't possible, what is a sane way for setting up an alternative indexing approach that would make this possible? Could I add a field per user in the index to store their scores? I'm thinking in the order of 1000 users. The major drawback of that approach is the number of times a document would need to be reindexed (i.e. each time it was used by the user).

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  • Slow Speeds when unzipping with PHP onto a NFS, how can I speed it up?

    - by bunwich
    Hi, I'm trying to figure out how to boost my NFS speed and php uploads. File is uploaded to the webserver's local tmp dir With PHP I copy the file userxxx.zip to the NFS With PHP I extract the userxxx.zip on the NFS to another dir on the NFS. What I'm finding is the file is in Step 3, the file is being read through the NFS by the web server, processed by the web server, and uploaded back across the NFS. Speeds as expected are very slow. Might a possible solution be to get the Fileserver to extract the zip? a) Webserver copies the file to the NFS b) Webserver makes a web service call to the Fileserver c) Fileserver can now unzip the file like it's local and the speeds should be much faster. I would appreciate any suggestion anyone how people have approached this problem. (I'm aware that php ZipArchive() is very slow, and I'll likely use java or php exec unzip to speed it up) Thanks

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  • ruby block and returning something from block

    - by dorelal
    I am using ruby 1.8.7. p = lambda { return 10;} def lab(block) puts 'before' puts block.call puts 'after' end lab p Above code output is before 10 after I refactored same code into this def lab(&block) puts 'before' puts block.call puts 'after' end lab { return 10; } Now I am getting LocalJumpError: unexpected return. To me both the code are doing same thing. Yes in the first case I am passing a proc and in the second case I am passing a block. But &block converts that block into proc. So proc.call should behave same. And yes I have seen this post http://stackoverflow.com/questions/2325471/using-return-in-a-ruby-block

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  • Why is one Func valid and the other (almost identical) not.

    - by runrunraygun
    private static Dictionary<Type, Func<string, object>> _parseActions = new Dictionary<Type, Func<string, object>> { { typeof(bool), value => {Convert.ToBoolean(value) ;}} }; The above gives an error Error 14 Not all code paths return a value in lambda expression of type 'System.Func<string,object>' However this below is ok. private static Dictionary<Type, Func<string, object>> _parseActions = new Dictionary<Type, Func<string, object>> { { typeof(bool), value => Convert.ToBoolean(value) } }; I don't understand the difference between the two. I thought the extra braces in example1 are to allow us to use multiple lines in the anon function so why have they affected the meaning of the code?

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  • Installing a condition handler in Common Lisp

    - by Paul Nathan
    The HTTP library Drakma on CLISP generates an error USOCKET:UNSUPPORTED due to a bug in Drakma+CLISP. However, it turns out that the CONTINUE restart seems to work fine. Therefore, I spent some time with CLtL and other references trying to determine how to write a restart handler. (defun http-request (url param) (handler-bind ((USOCKET:UNSUPPORTED #'(lambda (x) (invoke-restart 'continue))))) (drakma:http-request url :method :post :parameters param)) According to my best understanding, the above code should trap the error USOCKET:UNSUPPORTED. It doesn't; it seems to ignore the error binder. How do I fix this?

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  • Entity Framework query builder methods: why "it" and not lambdas?

    - by nlawalker
    I'm just getting started with EF and a query like the following strikes me as odd: var departmentQuery = schoolContext.Departments.Include("Courses"). OrderBy("it.Name"); Specifically, what sticks out to me is "it.Name." When I was tooling around with LINQ to SQL, pretty much every filter in a query-builder query could be specified with a lambda, like, in this case, d = d.Name. I see that there are overrides of OrderBy that take lambdas that return an IOrderedQueryable or an IOrderedEnumable, but those obviously don't have the Execute method needed to get the ObjectResult that can then be databound. It seems strange to me after all I've read about how lambdas make so much sense for this kind of stuff, and how they are translated into expression trees and then to a target language - why do I need to use "it.Name"?

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  • EHsc vc EHa (synchronous vs asynchronous exception handling)

    - by watson1180
    Could you give a bullet list of practical differences/implication? I read relevant MSDN article, but my understanding asynchronous exceptions is still a bit hazy. I am writing a test suite using Boost.Test and my compiler emits a warning that EHa should be enabled: warning C4535: calling _set_se_translator() requires /EHa The project itself uses only plain exceptions (from STL) and doesn't need /EHa switch. Do I have to recompile it with /EHa switch to make the test suite work properly? My feeling is that I need /EHa for the test suit only. Thank you and happy new year.

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