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• Are programming languages and methods inefficient? (assembler and C knowledge needed)

  - by b-gen-jack-o-neill

  Hi, for a long time, I am thinking and studying output of C language compiler in assembler form, as well as CPU architecture. I know this may be silly to you, but it seems to me that something is very ineffective. Please, don´t be angry if I am wrong, and there is some reason I do not see for all these principles. I will be very glad if you tell me why is it designed this way. I actually truly believe I am wrong, I know the genius minds of people which get PCs together knew a reason to do so. What exactly, do you ask? I´ll tell you right away, I use C as a example: 1: Stack local scope memory allocation: So, typical local memory allocation uses stack. Just copy esp to ebp and than allocate all the memory via ebp. OK, I would understand this if you explicitly need allocate RAM by default stack values, but if I do understand it correctly, modern OS use paging as a translation layer between application and physical RAM, when address you desire is further translated before reaching actual RAM byte. So why don´t just say 0x00000000 is int a,0x00000004 is int b and so? And access them just by mov 0x00000000,#10? Because you wont actually access memory blocks 0x00000000 and 0x00000004 but those your OS set the paging tables to. Actually, since memory allocation by ebp and esp use indirect addressing, "my" way would be even faster. 2: Variable allocation duplicity: When you run application, Loader load its code into RAM. When you create variable, or string, compiler generates code that pushes these values on the top o stack when created in main. So there is actual instruction for do so, and that actual number in memory. So, there are 2 entries of the same value in RAM. One in form of instruction, second in form of actual bytes in the RAM. But why? Why not to just when declaring variable count at which memory block it would be, than when used, just insert this memory location?

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• In Fluent NHibernate, how would I map the following domain models?

  - by Brandon

  I have a user class that looks something like this public class User { public virtual int Id { get; set; } public virtual long ValueA { get; set; } public virtual int? ValueB { get; set; } } ValueA is automatically assigned by the system. It is used in a lookup that would map to UserClass. However, if a value for ValueB exists, then it would do the lookup for UserClass in a different way. Right now the way I handle it is to get the User and then perform a separate lookup each time. return user.ValueB.HasValue ? Find(user.ValueB.Value) : Find(user.ValueA); Is there any way to make Fluent NHibernate do this for me so I can have UserClass as a property on the User class instead of having to do the lookup separately? I was thinking of the ComponentMap but I'm not sure how to make it account for the two possible lookup values.

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• How do I optimize this postfix expression tree for speed?

  - by Peter Stewart

  Thanks to the help I received in this post: I have a nice, concise recursive function to traverse a tree in postfix order: deque <char*> d; void Node::postfix() { if (left != __nullptr) { left->postfix(); } if (right != __nullptr) { right->postfix(); } d.push_front(cargo); return; }; This is an expression tree. The branch nodes are operators randomly selected from an array, and the leaf nodes are values or the variable 'x', also randomly selected from an array. char *values[10]={"1.0","2.0","3.0","4.0","5.0","6.0","7.0","8.0","9.0","x"}; char *ops[4]={"+","-","*","/"}; As this will be called billions of times during a run of the genetic algorithm of which it is a part, I'd like to optimize it for speed. I have a number of questions on this topic which I will ask in separate postings. The first is: how can I get access to each 'cargo' as it is found. That is: instead of pushing 'cargo' onto a deque, and then processing the deque to get the value, I'd like to start processing it right away. I don't yet know about parallel processing in c++, but this would ideally be done concurrently on two different processors. In python, I'd make the function a generator and access succeeding 'cargo's using .next(). But I'm using c++ to speed up the python implementation. I'm thinking that this kind of tree has been around for a long time, and somebody has probably optimized it already. Any Ideas? Thanks

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• Is it possible to include a Sexpr before the expression has been evaluated in Sweave / R ?

  - by PaulHurleyuk

  Hello, I'm writing a Sweave document, and I want to include a small section that details the R and package versions, platofrms and how long ti took to evalute the doucment, however, I want to put this in the middle of the document ! I was using a \Sexpr{elapsed} to do this (which didn't work), but thought if I put the code printing elapsed in a chunk that evaluates at the end, I could then include the chunk half way through, which also fails. My document looks something like this % \documentclass[a4paper]{article} \usepackage[OT1]{fontenc} \usepackage{longtable} \usepackage{geometry} \usepackage{Sweave} \geometry{left=1.25in, right=1.25in, top=1in, bottom=1in} \begin{document} <<label=start, echo=FALSE, include=FALSE>>= startt<-proc.time()[3] @ Text and Sweave Code in here % This document was created on \today, with \Sexpr{print(version$version.string)} running on a \Sexpr{print(version$platform)} platform. It took approx sec to process. <<>>= <<elapsed>> @ More text and Sweave code in here <<label=bye, include=FALSE, echo=FALSE>>= odbcCloseAll() endt<-proc.time()[3] elapsedtime<-as.numeric(endt-startt) @ <<label=elapsed, include=FALSE, echo=FALSE>>= print(elapsedtime) @ \end{document} But this doesn't seem to work (amazingly !) Does anyone know how I could do this ? Thanks Paul.

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• Undefined Web.config error in VS 2008

  - by user1066050

  I'm working on a web app using VS 2008, .Net 3.5 and C#. Most of the projects in the solution are either classic asp.net pages with some MVC 1 in the mix, the rest is shared libraries. The solution is one that is some 5 years old and has gone through a variety of developers working on it and clearly has some performance and architectural issues. Previously, I've been working on the project using VS 2008 on a Win XP machine, but have just transitioned over to a new box using Win 7 Ultimate. To do so, I've installed VS 2008, asp.net 3.5. To support future work on the solution I've also installed VS 2010 and asp.net 4.0. Opening the solution on the new box with VS 2008 works fine, and it builds without error. However, when I attempt to run it with the debugger, I get the following message: "There is an error in web.config. Please correct before proceeding. (You might rename the current web.config and add a new one.)" I think it's clear that there is some sort of environmental issue regarding web.config on the new machine, but the error message is not "helpful". Adding a new web.config is not an option as the existing one is quite long and involved (too much to post here). I'm hoping someone has a suggestion or two about where I might look for missing elements or changed configurations that might produce such an error message. Lacking that, I'll revisit this post and provide the web.config in the hope that will elicit further help. Thanks to all in advance for taking a look at this. The StackOverflow community has helped me many times in the past with pertinent answers although this is my first posting. Jeff

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• Encapsulating user input of data for a class (C++)

  - by Dr. Monkey

  For an assignment I've made a simple C++ program that uses a superclass (Student) and two subclasses (CourseStudent and ResearchStudent) to store a list of students and print out their details, with different details shown for the two different types of students (using overriding of the display() method from Student). My question is about how the program collects input from the user of things like the student name, ID number, unit and fee information (for a course student) and research information (for research students): My implementation has the prompting for user input and the collecting of that input handled within the classes themselves. The reasoning behind this was that each class knows what kind of input it needs, so it makes sense to me to have it know how to ask for it (given an ostream through which to ask and an istream to collect the input from). My lecturer says that the prompting and input should all be handled in the main program, which seems to me somewhat messier, and would make it trickier to extend the program to handle different types of students. I am considering, as a compromise, to make a helper class that handles the prompting and collection of user input for each type of Student, which could then be called on by the main program. The advantage of this would be that the student classes don't have as much in them (so they're cleaner), but also they can be bundled with the helper classes if the input functionality is required. This also means more classes of Student could be added without having to make major changes to the main program, as long as helper classes are provided for these new classes. Also the helper class could be swapped for an alternative language version without having to make any changes to the class itself. What are the major advantages and disadvantages of the three different options for user input (fully encapsulated, helper class or in the main program)?

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• Generic version control strategy for select table data within a heavily normalized database

  - by leppie

  Hi Sorry for the long winded title, but the requirement/problem is rather specific. With reference to the following sample (but very simplified) structure (in psuedo SQL), I hope to explain it a bit better. TABLE StructureName { Id GUID PK, Name varchar(50) NOT NULL } TABLE Structure { Id GUID PK, ParentId GUID (FK to Structure), NameId GUID (FK to StructureName) NOT NULL } TABLE Something { Id GUID PK, RootStructureId GUID (FK to Structure) NOT NULL } As one can see, Structure is a simple tree structure (not worried about ordering of children for the problem). StructureName is a simplification of a translation system. Finally 'Something' is simply something referencing the tree's root structure. This is just one of many tables that need to be versioned, but this one serves as a good example for most cases. There is a requirement to version to any changes to the name and/or the tree 'layout' of the Structure table. Previous versions should always be available. There seems to be a few possibilities to tackle this issue, like copying the entire structure, but most approaches causes one to 'loose' referential integrity. Example if one followed this approach, one would have to make a duplicate of the 'Something' record, given that the root structure will be a new record, and have a new ID. Other avenues of possible solutions are looking into how Wiki's handle this or go a lot further and look how proper version control systems work. Currently, I feel a bit clueless how to proceed on this in a generic way. Any ideas will be greatly appreciated. Thanks leppie

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• Dealing with multiple generics in a method call

  - by thaBadDawg

  I've been dealing a lot lately with abstract classes that use generics. This is all good and fine because I get a lot of utility out of these classes but now it's making for some rather ugly code down the line. For example: abstract class ClassBase<T> { T Property { get; set; } } class MyClass : ClassBase<string> { OtherClass PropertyDetail { get; set; } } This implementation isn't all that crazy, except when I want to reference the abstract class from a helper class and then I have to make a list of generics just to make reference to the implemented class, like this below. class Helper { void HelpMe<C, T>(object Value) where C : ClassBase<T>, new() { DoWork(); } } This is just a tame example, because I have some method calls where the list of where clauses end up being 5 or 6 lines long to handle all of the generic data. What I'd really like to do is class Helper { void HelpMe<C>(object Value) where C : ClassBase, new() { DoWork(); } } but it obviously won't compile. I want to reference ClassBase without having to pass it a whole array of generic classes to get the function to work, but I don't want to reference the higher level classes because there are a dozen of those. Am I the victim of my own cleverness or is there an avenue that I haven't considered yet?

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• How To Deal With Exceptions In Large Code Bases

  - by peter

  Hi All, I have a large C# code base. It seems quite buggy at times, and I was wondering if there is a quick way to improve finding and diagnosing issues that are occuring on client PCs. The most pressing issue is that exceptions occur in the software, are caught, and even reported through to me. The problem is that by the time they are caught the original cause of the exception is lost. I.e. If an exception was caught in a specific method, but that method calls 20 other methods, and those methods each call 20 other methods. You get the picture, a null reference exception is impossible to figure out, especially if it occured on a client machine. I have currently found some places where I think errors are more likely to occur and wrapped these directly in their own try catch blocks. Is that the only solution? I could be here a long time. I don't care that the exception will bring down the current process (it is just a thread anyway - not the main application), but I care that the exceptions come back and don't help with troubleshooting. Any ideas? I am well aware that I am probably asking a question which sounds silly, and may not have a straightforward answer. All the same some discussion would be good.

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• TEXTAREAs scroll by themselves (on IE8) every time you type one character

  - by Justin Grant

  IE8 has a known bug (per connect.microsoft.com) where typing or pasting text into a TEXTAREA element will cause the textarea to scroll by itself. This is hugely annoying and shows up in many community sites, including Wikipedia. The repro is this: open the HTML below with IE8 (or use any long page on wikipedia which will exhibit the same problem until they fix it) size the browser full-screen paste a few pages of text into the TEXTAREA move the scrollbar to the middle position now type one character into the textarea Expected: nothing happens Actual: scrossing happens on its own, and the insertion point ends up near the bottom of the textarea! Below is repro HTML (can also see this live on the web here: http://en.wikipedia.org/w/index.php?title=Text_box&action=edit) <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <body> <div style="width: 80%"> <textarea rows="20" cols="80" style="width:100%;" ></textarea> </div> </body> </html>

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• JQuery UI drag and drop doesn't notice DOM changes happening during the dragging ?

  - by user315677

  Hi everybody, I have a html table in which each line (<tr>) represents a group of client computers. Each line can be expanded to show the clients belonging to the group. The <tr> containing the clients are always generated but hidden and showed when clicking the plus button at the beginning of each line. The clients themselves (they are <div>) can be dragged and dropped in another group as long as this group is already expanded. So far it works fine. What I am trying to achieve now is that the client can be dragged to a collapsed group and after a second or so hovering the group it will be expanded and the client can be dropped amongst the other clients of the group. I programmed the hover using the in and outevents of the droppable and it expands the group all right, but (and now it starts to be hard to explain with words ;) the behavior of the droppable (the client) is still as if the table line that appeared were not there : the in out and drop events of the droppable are fired on the old position of the elements, and the in out and drop events of the newly appeared <tr> are never fired. It looks as if JQuery memorizes the position, size etc. of the elements when the drag starts, and these values are not updated if there is a change in the DOM before the drop happens... Can someone confirm this behavior is normal, or can it be caused by another problem in my own code ? Any workaround ? (the question is quite bloated already so I don't include any code but I'll gladly upload it if required)

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• Queries within queries: Is there a better way?

  - by mririgo

  As I build bigger, more advanced web applications, I'm finding myself writing extremely long and complex queries. I tend to write queries within queries a lot because I feel making one call to the database from PHP is better than making several and correlating the data. However, anyone who knows anything about SQL knows about JOINs. Personally, I've used a JOIN or two before, but quickly stopped when I discovered using subqueries because it felt easier and quicker for me to write and maintain. Commonly, I'll do subqueries that may contain one or more subqueries from relative tables. Consider this example: SELECT (SELECT username FROM users WHERE records.user_id = user_id) AS username, (SELECT last_name||', '||first_name FROM users WHERE records.user_id = user_id) AS name, in_timestamp, out_timestamp FROM records ORDER BY in_timestamp Rarely, I'll do subqueries after the WHERE clause. Consider this example: SELECT user_id, (SELECT name FROM organizations WHERE (SELECT organization FROM locations WHERE records.location = location_id) = organization_id) AS organization_name FROM records ORDER BY in_timestamp In these two cases, would I see any sort of improvement if I decided to rewrite the queries using a JOIN? As more of a blanket question, what are the advantages/disadvantages of using subqueries or a JOIN? Is one way more correct or accepted than the other?

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• MS hotfix delayed delivery.

  - by MOE37x3

  I just requested a hotfix from support.microsoft.com and put in my email address, but I haven't received the email yet. The splash page I got after I requested the hotfix said: Hotfix Confirmation We will send these hotfixes to the following e-mail address: (my correct email address) Usually, our hotfix e-mail is delivered to you within five minutes. However, sometimes unforeseen issues in e-mail delivery systems may cause delays. We will send the e-mail from the “[email protected]” e-mail account. If you use an e-mail filter or a SPAM blocker, we recommend that you add “[email protected]” or the “microsoft.com” domain to your safe senders list. (The safe senders list is also known as a whitelist or an approved senders list.) This will help prevent our e-mail from going into your junk e-mail folder or being automatically deleted. I'm sure that the email is not getting caught in a spam catcher. How long does it normally take to get one of these hotfixes? Am I waiting for some human to approve it, or something? Should I just give up and try to get the file I need some other way? (Update: Replaced "[email protected]" with "(my correct email address)" to resolve Martín Marconcini's ambiguity.)

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• Tips for Using Multiple Development Systems

  - by Tim Lytle

  When I travel, I don't pack up the desktop I use in the office and take it with me. Maybe I should, but I don't. However, since I'm a contract programmer I like to be able to work wherever I am: I'm mostly thinking of web development here. Version Control goes a long way in keeping sane and working on multiple projects on multiple systems (two or three computers); however, there are the issues of: IDE settings - different display sizes mean the IDE settings can't be completely synced, if at all. Database - if the database is 'external' (even if it's running on the same system, it's not in version control), how do you maintain the needed syncs of structure. Development Stack - Some projects need non-standard extensions, libraries, etc installed. Just an overview of some of the hassle involved with developing on multiple systems. I'll probably end up asking some specific questions, but I thought a CW style tips might reveal some things I would even think to ask about. Update: I guess this would also address tips to make upgrading/replacing your development system easier (something I've just done). So, one tip per answer please, so the 'top' tips are easy to find. How do you make it easier to develop on multiple systems, or to transfer work after upgrading/replaceing a development system?

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• Async task ASP.net HttpContext.Current.Items is empty - How do handle this?

  - by GuruC

  We are running a very large web application in asp.net MVC .NET 4.0. Recently we had an audit done and the performance team says that there were a lot of null reference exceptions. So I started investigating it from the dumps and event viewer. My understanding was as follows: We are using Asyn Tasks in our controllers. We rely on HttpContext.Current.Items hashtable to store a lot of Application level values. Task<Articles>.Factory.StartNew(() => { System.Web.HttpContext.Current = ControllerContext.HttpContext.ApplicationInstance.Context; var service = new ArticlesService(page); return service.GetArticles(); }).ContinueWith(t => SetResult(t, "articles")); So we are copying the context object onto the new thread that is spawned from Task factory. This context.Items is used again in the thread wherever necessary. Say for ex: public class SomeClass { internal static int StreamID { get { if (HttpContext.Current != null) { return (int)HttpContext.Current.Items["StreamID"]; } else { return DEFAULT_STREAM_ID; } } } This runs fine as long as number of parallel requests are optimal. My questions are as follows: 1. When the load is more and there are too many parallel requests, I notice that HttpContext.Current.Items is empty. I am not able to figure out a reason for this and this causes all the null reference exceptions. 2. How do we make sure it is not null ? Any workaround if present ? NOTE: I read through in StackOverflow and people have questions like HttpContext.Current is null - but in my case it is not null and its empty. I was reading one more article where the author says that sometimes request object is terminated and it may cause problems since dispose is already called on objects. I am doing a copy of Context object - its just a shallow copy and not a deep copy.

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• Can some tell me why I am seg faulting in this simple C program?

  - by user299648

  I keep on getting seg faulted after I end my first for loop, and for the life of me I don't why. The file I'm scanning is just 18 strings in 18 lines. I thinks the problem is the way I'm mallocing the double pointer called picks, but I don't know exactly why. I'm am only trying to scanf strings that are less than 15 chars long, so I don't see the problem. Can someone please help. #include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_LENGTH 100 int main( int argc,char *argv[] ) { char* string = malloc( 15*sizeof(char) ); char** picks = malloc(15*sizeof(char*)); FILE* pick_file = fopen( argv[l], "r" ); int num_picks; for( num_picks=0 ; fgets( string, MAX_LENGTH, pick_file ) != NULL ; num_picks++ ) { scanf( "%s", picks+num_picks ); } //this is where i seg fault int x; for(x=0; x<num_picks;x++) printf("s\n", picks+x); }

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• PHP/WordPress Session CountDown

  - by Cameron

  I have the following code to show how long a user has left before their session will expire, I am using WordPress. How can I do this? Thanks <script> var obj_Span; var n_Seconds = 0; var n_Minutes = 0; var n_Hours = 0; function F_ConvertNumberToString ( n_Num ) { var str_Num = String(n_Num); if ( str_Num.length < 2 ) str_Num = "0" + str_Num; return str_Num; } function F_CountDown () { if ( n_Hours == 0 && n_Minutes == 0 && n_Seconds == 0 ) { obj_Span.innerHTML = "(Sorry, your session has expired.)"; } else { if ( n_Seconds >= 0 ) n_Seconds --; if ( n_Seconds < 0 ) { n_Minutes --; n_Seconds = 59; } if ( n_Minutes >= 0 ) { window.setTimeout ( "F_CountDown()", 1000 ); } if ( n_Minutes < 0 ) { n_Hours --; n_Minutes = 59; window.setTimeout ( "F_CountDown()", 1000 ); } F_UpdateDisplay (); } } function F_UpdateDisplay ( ) { if ( document.getElementById ) { if (n_Hours > 0 ) obj_Span.innerHTML = "(Remaining " + F_ConvertNumberToString(n_Hours) + ":" + F_ConvertNumberToString(n_Minutes) + ":" + F_ConvertNumberToString(n_Seconds) + ")"; else obj_Span.innerHTML = "(Remaining " + F_ConvertNumberToString(n_Minutes) + ":" + F_ConvertNumberToString(n_Seconds) + ")"; } } function F_StartCountDown ( n_Session ) { obj_Span = document.getElementById ( "CountDown" ); n_Minutes = n_Session; n_Hours = Math.floor(n_Minutes/60); n_Minutes = n_Minutes - (60*n_Hours); F_CountDown (); } </script> <script> F_StartCountDown ( " code here... " ); </script> <span id="CountDown"></span>

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• Why am I getting this error when overriding an inherited method?

  - by Sergio Tapia

  Here's my parent class: public abstract class BaseFile { public string Name { get; set; } public string FileType { get; set; } public long Size { get; set; } public DateTime CreationDate { get; set; } public DateTime ModificationDate { get; set; } public abstract void GetFileInformation(); public abstract void GetThumbnail(); } And here's the class that's inheriting it: public class Picture:BaseFile { public override void GetFileInformation(string filePath) { FileInfo fileInformation = new FileInfo(filePath); if (fileInformation.Exists) { Name = fileInformation.Name; FileType = fileInformation.Extension; Size = fileInformation.Length; CreationDate = fileInformation.CreationTime; ModificationDate = fileInformation.LastWriteTime; } } public override void GetThumbnail() { } } I thought when a method was overridden, I could do what I wanted with it. Any help please? :)

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• How Would a Newborn Baby Learn Web Programming?

  - by Mugatu

  Hello all, I chose that title because I equate my knowledge of web programming and web development with that of a newborn. Here's the shortest version of my story and what I'm looking to do: A friend and I have been coming up with website ideas for a couple years, mostly just jotting them down whenever we come up with a good, useful idea when browsing the web. For the past 6 months we've hired a couple different programmers to make a couple of the sites for us, but have been disappointed with how it's gone. Been too slow and too many miscommunications for our liking. So like the saying goes if you want something done right do it yourself, we're going to do it ourselves. I know nothing about programming, I've never written a line of code in my life. I consider myself very good with math and about as logical as you can get, but I have zero real-life programming knowledge. The sites we want to make are all pretty 'Web 2.0'ish', meaning user-generated content, commenting on posts, pages that change on the fly, etc. So here are some of my questions for anyone who's been there before: Is there a language you'd recommend learning first? Something that is a good indicator how most other languages work? What web programming languages do you recommend learning first based on popularity both now and the future. I don't want to learn a language that's going to be outdated by the time I'm an expert at it. Any specific books you'd recommend? Any general advice you'd give to someone literally starting at square zero for coding who plans on being in it for the long haul? Thanks in advance for the help

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• Non standard interaction among two tables to avoid very large merge

  - by riko

  Suppose I have two tables A and B. Table A has a multi-level index (a, b) and one column (ts). b determines univocally ts. A = pd.DataFrame( [('a', 'x', 4), ('a', 'y', 6), ('a', 'z', 5), ('b', 'x', 4), ('b', 'z', 5), ('c', 'y', 6)], columns=['a', 'b', 'ts']).set_index(['a', 'b']) AA = A.reset_index() Table B is another one-column (ts) table with non-unique index (a). The ts's are sorted "inside" each group, i.e., B.ix[x] is sorted for each x. Moreover, there is always a value in B.ix[x] that is greater than or equal to the values in A. B = pd.DataFrame( dict(a=list('aaaaabbcccccc'), ts=[1, 2, 4, 5, 7, 7, 8, 1, 2, 4, 5, 8, 9])).set_index('a') The semantics in this is that B contains observations of occurrences of an event of type indicated by the index. I would like to find from B the timestamp of the first occurrence of each event type after the timestamp specified in A for each value of b. In other words, I would like to get a table with the same shape of A, that instead of ts contains the "minimum value occurring after ts" as specified by table B. So, my goal would be: C: ('a', 'x') 4 ('a', 'y') 7 ('a', 'z') 5 ('b', 'x') 7 ('b', 'z') 7 ('c', 'y') 8 I have some working code, but is terribly slow. C = AA.apply(lambda row: ( row[0], row[1], B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))), axis=1).set_index(['a', 'b']) Profiling shows the culprit is obviously B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))). However, standard solutions using merge/join would take too much RAM in the long run. Consider that now I have 1000 a's, assume constant the average number of b's per a (probably 100-200), and consider that the number of observations per a is probably in the order of 300. In production I will have 1000 more a's. 1,000,000 x 200 x 300 = 60,000,000,000 rows may be a bit too much to keep in RAM, especially considering that the data I need is perfectly described by a C like the one I discussed above. How would I improve the performance?

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• Is there a FAST way to export and install an app on my phone, while signing it with my own keystore?

  - by Alexei Andreev

  So, I've downloaded my own application from the market and installed it on my phone. Now, I am trying to install a temporary new version from Eclipse, but here is the message I get: Re-installation failed due to different application signatures. You must perform a full uninstall of the application. WARNING: This will remove the application data! Please execute 'adb uninstall com.applicationName' in a shell. Launch canceled! Now, I really really don't want to uninstall the application, because I will lose all my data. One solution I found is to Export my application, creating new .apk, and then install it via HTC Sync (probably a different program based on what phone you have). The problem is this takes a long time to do, since I need to enter the password for the keystore each time and then wait for HTC Sync. It's a pain in the ass! So the question is: Is there a way to make Eclipse automatically use my keystore to sign the application (quickly and automatically)? Or perhaps to replace debug keystore with my own? Or perhaps just tell it to remember the password, so I don't have to enter it every time...? Or some other way to solve this problem?

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• How to update GUI thread/class from worker thread/class?

  - by user315182

  First question here so hello everyone. The requirement I'm working on is a small test application that communicates with an external device over a serial port. The communication can take a long time, and the device can return all sorts of errors. The device is nicely abstracted in its own class that the GUI thread starts to run in its own thread and has the usual open/close/read data/write data basic functions. The GUI is also pretty simple - choose COM port, open, close, show data read or errors from device, allow modification and write back etc. The question is simply how to update the GUI from the device class? There are several distinct types of data the device deals with so I need a relatively generic bridge between the GUI form/thread class and the working device class/thread. In the GUI to device direction everything works fine with [Begin]Invoke calls for open/close/read/write etc. on various GUI generated events. I've read the thread here (How to update GUI from another thread in C#?) where the assumption is made that the GUI and worker thread are in the same class. Google searches throw up how to create a delegate or how to create the classic background worker but that's not at all what I need, although they may be part of the solution. So, is there a simple but generic structure that can be used? My level of C# is moderate and I've been programming all my working life, given a clue I'll figure it out (and post back)... Thanks in advance for any help.

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• Android OS 2.2 Permissions: I have absolutely no idea why this simple piece of code doesn't work. Wh

  - by Kevin

  I'm just playing around with some code. I create an Activity and simply do something like this: long lo = currentTimeMillis(); System.out.println(lo); lo *= 3; System.out.println(lo); SystemClock.setCurrentTimeMillis(lo); System.out.println( currentTimeMillis() ); Yes, in my AndroidManifest.xml, I've added: <uses-permission android:name="android.permission.SET_TIME"></uses-permission> <uses-permission android:name="android.permission.SET_TIME_ZONE"></uses-permission> Nothing changes. The SystemClock is never reset...it just keeps on ticking. The error that I'm getting just says that the permission "SET_TIME" was not granted to the program. Protection level 3. The permissions are there...and in the API for 2.2 it says that this feature is supported now. I have no idea what I'm doing wrong. If android.content.Intent; comes into play, please explain. I don't really understand what the idea behind intents! Thanks for any help!

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• Do database engines other than SQL Server behave this way?

  - by Yishai

  I have a stored procedure that goes something like this (pseudo code) storedprocedure param1, param2, param3, param4 begin if (param4 = 'Y') begin select * from SOME_VIEW order by somecolumn end else if (param1 is null) begin select * from SOME_VIEW where (param2 is null or param2 = SOME_VIEW.Somecolumn2) and (param3 is null or param3 = SOME_VIEW.SomeColumn3) order by somecolumn end else select somethingcompletelydifferent end All ran well for a long time. Suddenly, the query started running forever if param4 was 'Y'. Changing the code to this: storedprocedure param1, param2, param3, param4 begin if (param4 = 'Y') begin set param2 = null set param3 = null end if (param1 is null) begin select * from SOME_VIEW where (param2 is null or param2 = SOME_VIEW.Somecolumn2) and (param3 is null or param3 = SOME_VIEW.SomeColumn3) order by somecolumn end else select somethingcompletelydifferent And it runs again within expected parameters (15 seconds or so for 40,000+ records). This is with SQL Server 2005. The gist of my question is this particular "feature" specific to SQL Server, or is this a common feature among RDBMS' in general that: Queries that ran fine for two years just stop working as the data grows. The "new" execution plan destroys the ability of the database server to execute the query even though a logically equivalent alternative runs just fine? This may seem like a rant against SQL Server, and I suppose to some degree it is, but I really do want to know if others experience this kind of reality with Oracle, DB2 or any other RDBMS. Although I have some experience with others, I have only seen this kind of volume and complexity on SQL Server, so I'm curious if others with large complex databases have similar experience in other products.

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• Basic security, PHP mySQl

  - by yuudachi

  So I am making a basic log-in page. I have a good idea of what to do, but I'm still unsure of some things. I have a database full of students and a password column of course. I know I'm going to use md5 encryption in that column. The student enters their e-mail and student ID, and they get e-mailed a password if correct. But, where do I create the password? Do I have to manually add the password (which is just a randomly generated string) in mySQL to all the students? And I am suppose to send the password to the student; how will I know what to send the student if the password is encrypted? I was thinking about generating the password when the student first enters their e-mail and student ID. They get an e-mail of the random string, and at the same time, I add the same random string to the database, encrypted. Is that how it's suppose to work though? And it feels unsafe doing that all on the same page. Sorry for the long-winded, newbish question. I find this all facisnating at the same time as well (AES and RSA encryption :O)

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