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• How to use SQLAlchemy to dump an SQL file from query expressions to bulk-insert into a DBMS?

  - by Mahmoud Abdelkader

  Please bear with me as I explain the problem, how I tried to solve it, and my question on how to improve it is at the end. I have a 100,000 line csv file from an offline batch job and I needed to insert it into the database as its proper models. Ordinarily, if this is a fairly straight-forward load, this can be trivially loaded by just munging the CSV file to fit a schema, but I had to do some external processing that requires querying and it's just much more convenient to use SQLAlchemy to generate the data I want. The data I want here is 3 models that represent 3 pre-exiting tables in the database and each subsequent model depends on the previous model. For example: Model C --> Foreign Key --> Model B --> Foreign Key --> Model A So, the models must be inserted in the order A, B, and C. I came up with a producer/consumer approach: - instantiate a multiprocessing.Process which contains a threadpool of 50 persister threads that have a threadlocal connection to a database - read a line from the file using the csv DictReader - enqueue the dictionary to the process, where each thread creates the appropriate models by querying the right values and each thread persists the models in the appropriate order This was faster than a non-threaded read/persist but it is way slower than bulk-loading a file into the database. The job finished persisting after about 45 minutes. For fun, I decided to write it in SQL statements, it took 5 minutes. Writing the SQL statements took me a couple of hours, though. So my question is, could I have used a faster method to insert rows using SQLAlchemy? As I understand it, SQLAlchemy is not designed for bulk insert operations, so this is less than ideal. This follows to my question, is there a way to generate the SQL statements using SQLAlchemy, throw them in a file, and then just use a bulk-load into the database? I know about str(model_object) but it does not show the interpolated values. I would appreciate any guidance for how to do this faster. Thanks!

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• SAP related testing

  - by mgj

  Dear all, One notion that has been prevalent mostly as rumours for many aspiring programmers is that the testing phase of the SDLC(Software Development Life Cycle) is not that challenging and interesting as one's job as a tester after a period of time becomes monotonous because a person does the same thing repeatedly over and over again. Thats why many have this complexion of looking for a developers job rather than that of testers. Don't testers have a space for themselves in software companies to grow..? Please feel free to express your views for or against this. How true is that, could you please give e.g.'s of instances( need not be practical, even theoretical would suffice) which actually contradict this statement wrt a tester's career specifically wrt the SAP domain. E.g.'s from other domains are also welcome. This question is not meant to hurt someone's feelings who is in the testing domain. Its just that for e.g. in my case I want to know what actually would be the challenge's a tester could also face in real life situations.Something that would make their job also interesting and fun-filled. I myself am pro-testing and also interested in pursuing testing as a profession in a sw co, just curious to know more about it so...:) Thanks..:)

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• Programmatically talking to a Serial Port in OS X or Linux

  - by deadprogrammer

  I have a Prolite LED sign that I like to set up to show scrolling search queries from a apache logs and other fun statistics. The problem is, my G5 does not have a serial port, so I have to use a usb to serial dongle. It shows up as /dev/cu.usbserial and /dev/tty.usbserial . When i do this everything seems to be hunky-dory: stty -f /dev/cu.usbserial speed 9600 baud; lflags: -icanon -isig -iexten -echo iflags: -icrnl -ixon -ixany -imaxbel -brkint oflags: -opost -onlcr -oxtabs cflags: cs8 -parenb Everything also works when I use the serial port tool to talk to it. If I run this piece of code while the above mentioned serial port tool, everthing also works. But as soon as I disconnect the tool the connection gets lost. #!/usr/bin/python import serial ser = serial.Serial('/dev/cu.usbserial', 9600, timeout=10) ser.write("<ID01><PA> \r\n") read_chars = ser.read(20) print read_chars ser.close() So the question is, what magicks do I need to perform to start talking to the serial port without the serial port tool? Is that a permissions problem? Also, what's the difference between /dev/cu.usbserial and /dev/tty.usbserial?

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• Asynchronous crawling F#

  - by jlezard

  When crawling on webpages I need to be careful as to not make too many requests to the same domain, for example I want to put 1 s between requests. From what I understand it is the time between requests that is important. So to speed things up I want to use async workflows in F#, the idea being make your requests with 1 sec interval but avoid blocking things while waiting for request response. let getHtmlPrimitiveAsyncTimer (uri : System.Uri) (timer:int) = async{ let req = (WebRequest.Create(uri)) :?> HttpWebRequest req.UserAgent<-"Mozilla" try Thread.Sleep(timer) let! resp = (req.AsyncGetResponse()) Console.WriteLine(uri.AbsoluteUri+" got response") use stream = resp.GetResponseStream() use reader = new StreamReader(stream) let html = reader.ReadToEnd() return html with | _ as ex -> return "Bad Link" } Then I do something like: let uri1 = System.Uri "http://rue89.com" let timer = 1000 let jobs = [|for i in 1..10 -> getHtmlPrimitiveAsyncTimer uri1 timer|] jobs |> Array.mapi(fun i job -> Console.WriteLine("Starting job "+string i) Async.StartAsTask(job).Result) Is this alright ? I am very unsure about 2 things: -Does the Thread.Sleep thing work for delaying the request ? -Is using StartTask a problem ? I am a beginner (as you may have noticed) in F# (coding in general actually ), and everything envolving Threads scares me :) Thanks !!

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• GDI+ double buffering in C++

  - by David Titarenco

  I haven't written anything with GDI for a while now (and never with GDI+), and I'm just working on a fun project, but for the life of me, I can't figure out how to double buffer GDI+ void DrawStuff(HWND hWnd) { HDC hdc; HDC hdcBuffer; PAINTSTRUCT ps; hdc = BeginPaint(hWnd, &ps); hdcBuffer = CreateCompatibleDC(hdc); Graphics graphics(hdc); graphics.Clear(Color::Black); // drawing stuff, i.e. bunnies: Image bunny(L"bunny.gif"); graphics.DrawImage(&bunny, 0, 0, bunny.GetWidth(), bunny.GetHeight()); BitBlt(hdc, 0,0, WIDTH , HEIGHT, hdcBuffer, 0,0, SRCCOPY); EndPaint(hWnd, &ps); } The above works (everything renders perfectly), but it flickers. If I change Graphics graphics(hdc); to Graphics graphics(hdcBuffer);, I see nothing (although I should be bitblt'ing the buffer-hWnd hdc at the bottom). My message pipeline is set up properly (WM_PAINT calls DrawStuff), and I'm forcing a WM_PAINT message every program loop by calling RedrawWindow(window, NULL, NULL, RDW_ERASE | RDW_INVALIDATE | RDW_UPDATENOW); I'm probably going about the wrong way to do this, any ideas? The MSDN documentation is cryptic at best.

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• Design considerations for temporarily transforming a player into an animal in a role playing game

  - by mikedev

  I am working on a role playing game for fun and to practice design patterns. I would like players to be able to transform themselves into different animals. For example, a Druid might be able to shape shift into a cheetah. Right now I'm planning on using the decorator pattern to do this but my question is - how do I make it so that when a druid is in the cheetah form, they can only access skills for the cheetah? In other words, they should not be able to access their normal Druid skills. Using the decorator pattern it appears that even in the cheetah form my druid will be able to access their normal druid skills. class Druid : Character { // many cool druid skills and spells void LightHeal(Character target) { } } abstract class CharacterDecorator : Character { Character DecoratedCharacter; } class CheetahForm : CharacterDecorator { Character DecoratedCharacter; public CheetahForm(Character decoratedCharacter) { DecoratedCharacter= decoratedCharacter; } // many cool cheetah related skills void CheetahRun() { // let player move very fast } } now using the classes Druid myDruid = new Druid(); myDruid.LightHeal(myDruid); // casting light heal here is fine myDruid = new CheetahForm(myDruid); myDruid.LightHeal(myDruid); // casting here should not be allowed Hmmmm...now that I think about it, will myDruid be unable to us the Druid class spells/skills unless the class is down-casted? But even if that's the case, is there a better way to ensure that myDruid at this point is locked out from all Druid related spells/skills until it is cast back to a Druid (since currently it's in CheetahForm)

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• My First F# program

  - by sudaly

  Hi I just finish writing my first F# program. Functionality wise the code works the way I wanted, but not sure if the code is efficient. I would much appreciate if someone could review the code for me and point out the areas where the code can be improved. Thanks Sudaly open System open System.IO open System.IO.Pipes open System.Text open System.Collections.Generic open System.Runtime.Serialization [<DataContract>] type Quote = { [<field: DataMember(Name="securityIdentifier") >] RicCode:string [<field: DataMember(Name="madeOn") >] MadeOn:DateTime [<field: DataMember(Name="closePrice") >] Price:float } let m_cache = new Dictionary<string, Quote>() let ParseQuoteString (quoteString:string) = let data = Encoding.Unicode.GetBytes(quoteString) let stream = new MemoryStream() stream.Write(data, 0, data.Length); stream.Position <- 0L let ser = Json.DataContractJsonSerializer(typeof<Quote array>) let results:Quote array = ser.ReadObject(stream) :?> Quote array results let RefreshCache quoteList = m_cache.Clear() quoteList |> Array.iter(fun result->m_cache.Add(result.RicCode, result)) let EstablishConnection() = let pipeServer = new NamedPipeServerStream("testpipe", PipeDirection.InOut, 4) let mutable sr = null printfn "[F#] NamedPipeServerStream thread created, Wait for a client to connect" pipeServer.WaitForConnection() printfn "[F#] Client connected." try // Stream for the request. sr <- new StreamReader(pipeServer) with | _ as e -> printfn "[F#]ERROR: %s" e.Message sr while true do let sr = EstablishConnection() // Read request from the stream. printfn "[F#] Ready to Receive data" sr.ReadLine() |> ParseQuoteString |> RefreshCache printfn "[F#]Quot Size, %d" m_cache.Count let quot = m_cache.["MSFT.OQ"] printfn "[F#]RIC: %s" quot.RicCode printfn "[F#]MadeOn: %s" (String.Format("{0:T}",quot.MadeOn)) printfn "[F#]Price: %f" quot.Price

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• advanced Visual Studio kung-fu test -- Calling functions from the Immediate Window during debugging

  - by kizzx2

  I see some related questions have been asked, but they're either too advanced for me to grasp or lacking a step-by-step guide from start to finish (most of them end up being insider talk of their own experiment results). OK here it is, given this simple program: #include <stdio.h> #include <string.h> int main() { FILE * f; char buffer[100]; memset(buffer, 0, 100); fun(); f = fopen("main.cpp", "r"); fread(buffer, 1, 99, f); printf(buffer); fclose(f); return 0; } What it does is basically print itself (assume file name is main.cpp). Question How can I have it print another file, say foobar.txt without modifying the source code? It has something to do with running it through VS's, stepping through the functions and hijacking the FILE pointer right before fread() is called. No need to worry about leaking resources by calling fclose(). I tried the simple f = fopen("foobar.txt", "r") which gave CXX0017: Error: symbol "fopen" not found Any ideas? Edit I found out the solution accidentally on Debugging Mozilla on Windows FAQ. The correct command to put into the Immediate Window is f = {,,MSVCR100D}fopen("foo.txt", "r") However, it doesn't really answer this question: I still don't understand what is going on here. How to systematically find out the {,,MSVCR100D} part for any given method? I know the MSVCR version changes from system to system. How can I find that out? Could anyone explain the curly brace syntax, especially, what are those two commas doing there? Are there more hidden gems using this syntax?

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• MATLAB Easter Egg Spy vs Spy

  - by Aqui1aZ3r0

  I heard that MATLAB 2009b or earlier had a fun function. When you typed spy in the console, you would get something like this: http://t2.gstatic.com/images?q=tbn:ANd9GcSHAgKz-y1HyPHcfKvBpYmZ02PWpe3ONMDat8psEr89K0VsP_ft However, now you have an image like this:http://undocumentedmatlab.com/images/spy2.png I'd like it if I could get the code of the original spy vs spy image FYI, there's a code, but has certain errors in it: c = [';@3EA4:aei7]ced.CFHE;4\T*Y,dL0,HOQQMJLJE9PX[[Q.ZF.\JTCA1dd' '-IorRPNMPIE-Y\R8[I8]SUDW2e+' '=4BGC;7imiag2IFOQLID8''XI.]K0"PD@l32UZhP//P988_WC,U+Z^Y\<2' '&lt;82BF>?8jnjbhLJGPRMJE9/YJ/L1#QMC$;;V[iv09QE99,XD.YB,[_]=3a' '9;CG?@9kokc2MKHQSOKF:0ZL0aM2$RNG%AAW\jw9E.FEE-_G8aG.d]_W5+' '?:CDH@A:lpld3NLIRTPLG=1[M1bN3%SOH4BBX]kx:J9LLL8H9bJ/+d_dX6,' '@;DEIAB;mqmePOMJSUQMJ2\N2cO4&TPP@HCY^lyDKEMMN9+I@+S8,+deY7^' '8@EFJBC<4rnfQPNPTVRNKB3]O3dP5''UQQCIDZ_mzEPFNNOE,RA,T9/,++\8_' '9A2G3CD=544gRQPQUWUOLE4^P4"Q6(VRRIJE[n{KQKOOPK-SE.W:F/,,]Z+' ':BDH4DE>655hSRQRVXVPMF5_Q5#R>)eSSJKF\ao0L.L-WUL.VF8XCH001_[,' ';3EI<eo ?766iTSRSWYWQNG6$R6''S?*fTTlLQ]bp1M/P.XVP8[H9]DIDA=]' '?4D3=FP@877jUTSTXZXROK7%S7(TF+gUUmMR^cq:N9Q8YZQ9_IcIJEBd_^' '@5E@GQA98b3VUTUY*YSPL8&T)UI,hVhnNS_dr;PE.9Z[RCaR?+JTFC?e+' '79FA?HRB:9c4WVUVZ+ZWQM=,WG*VJ-"gi4OTes-XH+bK.#hj@PUvftDRMEF,]UH,UB.TYVWX,e\' '9;ECAKTY< ;eWYXWX\:)YSOE.YI,cL/$ikCqV1guE/PFL-^XI-YG/WZWXY1+]' ':AFDBLUZ=jgY[ZYZ-<7[XQG0[K.eN1&"$K2u:iyO9.PN9-_K8aJ9_]]82[' '?CEFDNW\?khZ[Z[==8\YRH1\M/!O2''#%m31Bw0PE/QXE8+R9bS;da^]93\' '@2FGEOX]ali[][9(ZSL2]N0"P3($&n;2Cx1QN9--L9,SA+T< +d_:4,' 'A3GHFPY^bmj\^]\]??:)[TM3^O1%Q4)%''oA:D0:0OE.8ME-TE,XB,+da;5[' '643IGQZ_cnk]_^]^@@;5\UN4_P2&R6*&(3B;E1<1PN99NL8WF.^C/,a+bY6,' '7:F3HR[dol^_^AA<6]VO5Q3''S>+'');CBF:=:QOEEOO9_G8aH6/d,cZ[Y' '8;G4IS\aep4_a-BD=7''XP6aR4(T?,(5@DCHCC;RPFLPPDH9bJ70+0d\\Z' '9BH>JT^bf45ba.CE@8(YQ7#S5)UD-)?AEDIDDD/QKMVQJ+S?cSDF,1e]a,' ':C3?K4_cg5[acbaADFA92ZR8$T6*VE.*@JFEJEEE0.NNWTK,U@+TEG0?+_bX' ';2D@L9dh6\bdcbBEGD:3[S=)U7+cK/+CKGFLIKI9/OWZUL-VA,WIHB@,`cY']; i = double(c(:)-32); j = cumsum(diff([0; i])< =0) + 1; S = sparse(i,j,1)'; spy(S)

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• Need to format character precedence in Strings.

  - by Christian

  I'm currently writing a Roman Numeral Converter for the fun of it. The problem works up to the aforementioned character precedence. Since Roman Numerals are not positional, i.e. III does not symbolize 1*whatever base^2 + 1*whatever base^1 + 1*whatever base^0. That of course makes it hard when somebody types in XIV and I need to make sure that the I is not added in this case, but rather subtracted. I'm not sure how to do this. What would be the best approach to tackle this? I have both the Roman Symbols and their respective decimal numbers stored in arrays: const char cRomanArray[] = "IVXLCDM"; const int romanArray[] = { 1, 5, 10, 50, 100, 500, 1000 }; so it wouldn't be too hard for me to brute-force the damn thing by simply checking the precedence within the array, i.e. if the symbol is smaller than the next symbol, i.e. in the exampe 'XIV' if 'I' is smaller than 'V', in which case it would be because I have ordered them in the array, then I could make it subtract the value instead of add. But this seems like a very ugly solution. Are there perhaps any better ones? I was thinking something along the lines of Regular Expressions maybe( forgive me if that sounds like a horrible idea, I haven't used RegExp yet, but it sounds like it could do what I need, and that's to determine the characters in a string.)

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• Is ther any tool to extract keywords from a English Text or Article In Java?

  - by user555581

  Dear Experts, I am trying to identify the type of the web site(In English) by machine. I try to download the homepage of the web iste, download html page, parsing and get the content of the web page. Such as here are some context from CNN.com. I try to get the keywords of the web page, mapping with my database. If the keywords include like news, breaking news. The web site will go to the news web sites. If there exist some words like healthy, medical, it will be the medical web site. There exist some tools can do the text segmentation, but it is not easy to find a tool do the semantic, such as online shopping, it is a keywords, should not spilt two words. The combination will be helpful information. But "oneline", "shopping" will be less useful as it may exist online travel... • Newark, JFK airports reopen • 1 runway reopens at LaGuardia Airport • Over 4,155 flights were cancelled Monday • FULL STORY * LaGuardia Airport snowplows busy Video * Are you stranded? | Airport delays * Safety tips for winter weather * Frosty fun Video | Small dog, deep snow Latest news * Easter eggs used to smuggle cocaine * Salmonella forces cilantro, parsley recall * Obama's surprising verdict on Vick * Blue Note baritone Bernie Wilson dead * Busch aide to 911: She's not waking up * Girl, 15, last seen working at store in '90 * Teena Marie's death shocks fans * Terror network 'dismantled' in Morocco * Saudis: 'Militant' had al Qaeda ties * Ticker: Gov. blasts Obama 'birthers' * Game show goof is 800K mistakeVideo * Chopper saves calf on frozen pondVideo * Pickpocketing becomes hands-freeVideo * Chilean miners going to Disney World * Who's the most intriguing of 2010? * Natalie Portman is pregnant, engaged * 'Convert all gifts from aunt' CNNMoney * Who controls the thermostat at home? * This Just In: CNN's news blog

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• How to make a good programming interview?

  - by luckyluke

  I am doing interviews with from time to time to recruit some not bad people. And I really think I AM NOT doing to correct Job. I work in a company when We have to do a lot o DB programming, .NET programming, Java programming, so we need people who are open minded and not focused on a particular tech. Afterall language is a notation, You have to understand what is going under the hood. I ask people about their project, ask them some coding questions (believe me a SQL question involving a CROSS JOIN is hard), let them write some code, ask them about oo design, ask them how they update their knowledge, and stay up to date, do they have FUN when they code (at least sometimes). Hell I even give them a coding solution for home (3 hours max) to see how they think and code. And yet my hit rate at hiring junior member (those who live over the initial 3 months) is just about 33%. So my question, how do YOU make the good interviews, because I think my hit rate is to low? Do you have any best-practices(should be at least 60-70%)? p.s. And i noticed that: the best programmers are lazy, but motivated, just being lazy is not enough:) But people who write the best code are attentive to details:)

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• Flex 3: should I provide prepared data to my component or make it to process data before display?

  - by grapkulec

  I'm starting to learn a little Flex just for fun and maybe to prove that I still can learn something new :) I have some idea for a project and one of its parts is a tree component which could display data in different ways depending on configuration. The idea There is list of objects having properties like id, date, time, name, description. And sometimes list should be displayed like this: first level: date second level: time third level: name and sometimes like this: first level: year second level: month third level: day fourth level: time and name By level I mean level of nesting of course. So, we can have years, that have months, that have days, that have hours and so forth. The problem What could be the best way to do it? I mean, should I prepare data for different ways of nesting outside of component or even outside of flex? I can do it at web service level in C# where I plan to have database access layer and send to flex nice and ready to display XML or array of objects. But I wonder if that won't cause additional and maybe unneccessary network traffic. I tried to hack some code in my component to convert my data objects into XML or ArrayCollection but I don't know enough of Flex and got stuck on elimination of duplicates or getting specific data by some key value. Usually to do such things I have STL with maps, sets and vectors and I find Flex arrays and even Dictionary a little bit confusing (I've read language reference and googled without any significant luck). The question So, to sum things up: should I give my tree component data prepared just for chosen type of display or should I try to do it internally inside component (or some helper class written in ActionScript)?

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• "Pattern matching" of algebraic type data constructors

  - by jetxee

  Let's consider a data type with many constructors: data T = Alpha Int | Beta Int | Gamma Int Int | Delta Int I want to write a function to check if two values are produced with the same constructor: sameK (Alpha _) (Alpha _) = True sameK (Beta _) (Beta _) = True sameK (Gamma _ _) (Gamma _ _) = True sameK _ _ = False Maintaining sameK is not much fun, it is potentially buggy. For example, when new constructors are added to T, it's easy to forget to update sameK. I omitted one line to give an example: -- it’s easy to forget: -- sameK (Delta _) (Delta _) = True The question is how to avoid boilerplate in sameK? Or how to make sure it checks for all T constructors? The workaround I found is to use separate data types for each of the constructors, deriving Data.Typeable, and declaring a common type class, but I don't like this solution, because it is much less readable and otherwise just a simple algebraic type works for me: {-# LANGUAGE DeriveDataTypeable #-} import Data.Typeable class Tlike t where value :: t -> t value = id data Alpha = Alpha Int deriving Typeable data Beta = Beta Int deriving Typeable data Gamma = Gamma Int Int deriving Typeable data Delta = Delta Int deriving Typeable instance Tlike Alpha instance Tlike Beta instance Tlike Gamma instance Tlike Delta sameK :: (Tlike t, Typeable t, Tlike t', Typeable t') => t -> t' -> Bool sameK a b = typeOf a == typeOf b

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• How can a program be detected as running?

  - by ryeguy

  I have written a program that is sort of an unofficial, standalone plugin for an application. It allows customers to get a service that is a lower priced alternative then the vendor-owned one. My program is not illegal, against any kind of TOS, and is certainly not a virus, adware, or anything like that. That being said, the vendor of course is not happy about me taking his competition, and is trying to block my application from running. He has already tried some tactics to stop people from running my app alongside his. He makes it so if it is detected, his app throws a fake error. First, he checked to see if my program was running by looking for an open window with the right title. I countered this by randomizing the program title at startup. Next, he looked for the running process name. I countered this by making the app copy itself when it is started as [random string].exe and then running that. Anyways, my question is this: what else can he do to detect if my program running? I know that you can read window text (ie status bar, labels). I'm prepared to counter this by replacing the labels with images (ugh, any other way?). But what else is there? Can you detect what .dlls a program has loaded? If so, could this be solved by randomizing the dll names before loading them? I know that it's possible to get a program's signature in memory and track it that way (like a virus scanner), but the chances of him doing that probably aren't good because that sounds pretty advanced. Even though this is kinda crappy of him to be doing, its kind of fun. It's like a nerdy fist fight. EDIT: When I said it's a plugin, that is just the (incorrect) term I used. It's a standalone EXE. The "API" between my program and the other is mine is simply entering data into the controls (like textboxes, etc).

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• What is the fastest, most efficient way to get up to speed on a new technology?

  - by SLC

  My current job involves working with a huge number of technologies, most of which are very niche and unheard of. In some cases I have to write something about the technology, or with the technology, such as some lessons, examples, or tutorials, on behalf of the developer of that technology or someone that is backing it. When I get told to learn about a new technology, my first port of call is to check our internal library, and then look on amazon for a book on the subject. Failing that, or if the project is too small to warrant a purchase, I hit up google and youtube. However the results of randomly googling what I want to learn are hit and miss. Some days, I can find everything I want to know in a series of lessons or videos, and it's no problem. Other times, I can find almost nothing, and I really have to piece together things from sites. The result is that there are various resources out there, videos, interactive lessons, tutorials, books etc. but when I need to learn something fast, I often don't know the best way to go about it. It's not about fun, because I don't always have the luxury of working my way through a 600 page textbook named "A Complete Guide To Technology X", I have to deliver results quickly. One of the examples I'd like to use is ASP.NET MVC 2 which is something I have been told to learn. I grabbed a book on MVC 1 to refresh my knowledge, but googling it does't produce much useful information. I've seen a ton of ScottGu's tutorials on it, but they are mostly feature presentations, and some date back almost a year. The same applies to channel 9 and there are no books out yet on amazon. My question therefore has two parts, the first asks, "Where are the best places to look to get the information needed to learn a new technology?" and the second asks "What is the most efficient way to use such resources to learn a new technology?"

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• malloc works, cudaHostAlloc segfaults?

  - by Mikhail

  I am new to CUDA and I want to use cudaHostAlloc. I was able to isolate my problem to this following code. Using malloc for host allocation works, using cudaHostAlloc results in a segfault, possibly because the area allocated is invalid? When I dump the pointer in both cases it is not null, so cudaHostAlloc returns something... works in_h = (int*) malloc(length*sizeof(int)); //works for (int i = 0;i<length;i++) in_h[i]=2; doesn't work cudaHostAlloc((void**)&in_h,length*sizeof(int),cudaHostAllocDefault); for (int i = 0;i<length;i++) in_h[i]=2; //segfaults Standalone Code #include <stdio.h> void checkDevice() { cudaDeviceProp info; int deviceName; cudaGetDevice(&deviceName); cudaGetDeviceProperties(&info,deviceName); if (!info.deviceOverlap) { printf("Compute device can't use streams and should be discared."); exit(EXIT_FAILURE); } } int main() { checkDevice(); int *in_h; const int length = 10000; cudaHostAlloc((void**)&in_h,length*sizeof(int),cudaHostAllocDefault); printf("segfault comming %d\n",in_h); for (int i = 0;i<length;i++) { in_h[i]=2; } free(in_h); return EXIT_SUCCESS; } ~ Invocation [id129]$ nvcc fun.cu [id129]$ ./a.out segfault comming 327641824 Segmentation fault (core dumped) Details Program is run in interactive mode on a cluster. I was told that an invocation of the program from the compute node pushes it to the cluster. Have not had any trouble with other home made toy cuda codes.

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• Which book should I choose?

  - by sebastianlarsson

  Hi guys, I'm looking for a good read on object oriented design. The two books I'm currently looking Head First Design Patterns and Head First Object object-oriented analysis & design. They seem very similar when looking at the contents and browsing through available sample text. Which one would be the best choice? About myself: I have a bachelor in computer science and I am currently studying Msc. Software Quality Engineering (read Software Engineering with focus on Quality). I am already confident in object-oriented design and have a lot of programming courses in my backpack. I have done games in c++, courses in advanced java programming (I am SCJP certified), but my preferred language is C#. I have also worked with Java for the last 7 months while studying. I am currently also studying for certificates in C# (apart from my usual studies). So I believe I have the prerequisites of actually understanding the contents of both books. Reason: I just want to be better and keep evolving as a programmer. I think it is fun. I believe Bert Bates and Kathy Sierra are involved in both these books and I have previously read their SCJP preparation book in java. I really do enjoy their style of writing. Other books which I am considering are: Clean Code: A Handbook Of Agile Software Craftsmanship Thx in advance Sebastian

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• How do I get LongVarchar out param from SPROC in ADO.NET 2.0 with SQLAnywhere 10?

  - by todthomson

  Hi All, I have sproc 'up_selfassessform_view' which has the following parameters: in ai_eqidentkey SYSKEY in ai_acidentkey SYSKEY out as_eqcomments TEXT_STRING out as_acexplanation TEXT_STRING  -  which are domain objects - SYSKEY is 'integer' and TEXT_STRING is 'long varchar'. I can call the sproc fine from iSQL using the following code: create variable @eqcomments TEXT_STRING; create variable @acexamples TEXT_STRING; call up_selfassessform_view (75000146, 3, @eqcomments, @acexamples); select @eqcomments, @acexamples;  - which returns the correct values from the DB (so I know the SPROC is good). I have configured the out param in ADO.NET like so (which has worked up until now for 'integer', 'timestamp', 'varchar(255)', etc): SAParameter as_acexplanation = cmd.CreateParameter(); as_acexplanation.Direction = ParameterDirection.Output; as_acexplanation.ParameterName = "as_acexplanation"; as_acexplanation.SADbType = SADbType.LongVarchar; cmd.Parameters.Add(as_acexplanation); When I run the following code: SADataReader reader = cmd.ExecuteReader(); I receive the following error: Parameter[2]: the Size property has an invalid size of 0. Which (I suppose) makes sense... But the thing is, I don't know the size of the field (it's just "long varchar" it doesn't have a predetermined length - unlike varchar(XXX)). Anyhow, just for fun, I add the following: as_acexplanation.Size = 1000; and the above error goes away, but now when I call: as_acexplanation.Value i get back a string of length = 1000 which is just '\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0...' (\0 repeated 1000 times). So I'm really really stuck... Any help one this one would be much appreciated. Cheers! ;) Tod T.

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• HTTP crawler in Erlang

  - by ctp

  I'm coding on a simple HTTP crawler but I have an issue running the code at the bottom. I'm requesting 50 URLs and get the content of 20+ back. I've generated few files with 150kB size each to test the crawler. So I think the 20+ responses are limited by the bandwidth? BUT: how to tell the Erlang snippet not to quit until the last file is not fetched? The test data server is online, so plz try the code out and any hints are welcome :) -module(crawler). -define(BASE_URL, "http://46.4.117.69/"). -export([start/0, send_reqs/0, do_send_req/1]). start() -> ibrowse:start(), proc_lib:spawn(?MODULE, send_reqs, []). to_url(Id) -> ?BASE_URL ++ integer_to_list(Id). fetch_ids() -> lists:seq(1, 50). send_reqs() -> spawn_workers(fetch_ids()). spawn_workers(Ids) -> lists:foreach(fun do_spawn/1, Ids). do_spawn(Id) -> proc_lib:spawn_link(?MODULE, do_send_req, [Id]). do_send_req(Id) -> io:format("Requesting ID ~p ... ~n", [Id]), Result = (catch ibrowse:send_req(to_url(Id), [], get, [], [], 10000)), case Result of {ok, Status, _H, B} -> io:format("OK -- ID: ~2..0w -- Status: ~p -- Content length: ~p~n", [Id, Status, length(B)]); Err -> io:format("ERROR -- ID: ~p -- Error: ~p~n", [Id, Err]) end. That's the output: Requesting ID 1 ... Requesting ID 2 ... Requesting ID 3 ... Requesting ID 4 ... Requesting ID 5 ... Requesting ID 6 ... Requesting ID 7 ... Requesting ID 8 ... Requesting ID 9 ... Requesting ID 10 ... Requesting ID 11 ... Requesting ID 12 ... Requesting ID 13 ... Requesting ID 14 ... Requesting ID 15 ... Requesting ID 16 ... Requesting ID 17 ... Requesting ID 18 ... Requesting ID 19 ... Requesting ID 20 ... Requesting ID 21 ... Requesting ID 22 ... Requesting ID 23 ... Requesting ID 24 ... Requesting ID 25 ... Requesting ID 26 ... Requesting ID 27 ... Requesting ID 28 ... Requesting ID 29 ... Requesting ID 30 ... Requesting ID 31 ... Requesting ID 32 ... Requesting ID 33 ... Requesting ID 34 ... Requesting ID 35 ... Requesting ID 36 ... Requesting ID 37 ... Requesting ID 38 ... Requesting ID 39 ... Requesting ID 40 ... Requesting ID 41 ... Requesting ID 42 ... Requesting ID 43 ... Requesting ID 44 ... Requesting ID 45 ... Requesting ID 46 ... Requesting ID 47 ... Requesting ID 48 ... Requesting ID 49 ... Requesting ID 50 ... OK -- ID: 49 -- Status: "200" -- Content length: 150000 OK -- ID: 47 -- Status: "200" -- Content length: 150000 OK -- ID: 50 -- Status: "200" -- Content length: 150000 OK -- ID: 17 -- Status: "200" -- Content length: 150000 OK -- ID: 48 -- Status: "200" -- Content length: 150000 OK -- ID: 45 -- Status: "200" -- Content length: 150000 OK -- ID: 46 -- Status: "200" -- Content length: 150000 OK -- ID: 10 -- Status: "200" -- Content length: 150000 OK -- ID: 09 -- Status: "200" -- Content length: 150000 OK -- ID: 19 -- Status: "200" -- Content length: 150000 OK -- ID: 13 -- Status: "200" -- Content length: 150000 OK -- ID: 21 -- Status: "200" -- Content length: 150000 OK -- ID: 16 -- Status: "200" -- Content length: 150000 OK -- ID: 27 -- Status: "200" -- Content length: 150000 OK -- ID: 03 -- Status: "200" -- Content length: 150000 OK -- ID: 23 -- Status: "200" -- Content length: 150000 OK -- ID: 29 -- Status: "200" -- Content length: 150000 OK -- ID: 14 -- Status: "200" -- Content length: 150000 OK -- ID: 18 -- Status: "200" -- Content length: 150000 OK -- ID: 01 -- Status: "200" -- Content length: 150000 OK -- ID: 30 -- Status: "200" -- Content length: 150000 OK -- ID: 40 -- Status: "200" -- Content length: 150000 OK -- ID: 05 -- Status: "200" -- Content length: 150000 Update: thanks stemm for the hint with the wait_workers. I've combined your and mine code but same behaviour :( -module(crawler). -define(BASE_URL, "http://46.4.117.69/"). -export([start/0, send_reqs/0, do_send_req/2]). start() -> ibrowse:start(), proc_lib:spawn(?MODULE, send_reqs, []). to_url(Id) -> ?BASE_URL ++ integer_to_list(Id). fetch_ids() -> lists:seq(1, 50). send_reqs() -> spawn_workers(fetch_ids()). spawn_workers(Ids) -> %% collect reference to each worker Refs = [ do_spawn(Id) || Id <- Ids ], %% wait for response from each worker wait_workers(Refs). wait_workers(Refs) -> lists:foreach(fun receive_by_ref/1, Refs). receive_by_ref(Ref) -> %% receive message only from worker with specific reference receive {Ref, done} -> done end. do_spawn(Id) -> Ref = make_ref(), proc_lib:spawn_link(?MODULE, do_send_req, [Id, {self(), Ref}]), Ref. do_send_req(Id, {Pid, Ref}) -> io:format("Requesting ID ~p ... ~n", [Id]), Result = (catch ibrowse:send_req(to_url(Id), [], get, [], [], 10000)), case Result of {ok, Status, _H, B} -> io:format("OK -- ID: ~2..0w -- Status: ~p -- Content length: ~p~n", [Id, Status, length(B)]), %% send message that work is done Pid ! {Ref, done}; Err -> io:format("ERROR -- ID: ~p -- Error: ~p~n", [Id, Err]), %% repeat request if there was error while fetching a page, do_send_req(Id, {Pid, Ref}) %% or - if you don't want to repeat request, put there: %% Pid ! {Ref, done} end. Running the crawler forks fine for a handful of files, but then the code even doesnt fetch the entire files (file size each 150000 bytes) - he crawler fetches some files partially, see the following web server log :( 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /10 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /1 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /3 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /8 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /39 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /7 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /6 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /2 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /5 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /50 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /9 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /44 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /38 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /47 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /49 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /43 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /37 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /46 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /48 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:00 +0200] "GET /36 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:01 +0200] "GET /42 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:01 +0200] "GET /41 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:01 +0200] "GET /45 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:01 +0200] "GET /17 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:01 +0200] "GET /35 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:01 +0200] "GET /16 HTTP/1.1" 200 150000 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:01 +0200] "GET /15 HTTP/1.1" 200 17020 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:01 +0200] "GET /21 HTTP/1.1" 200 120360 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:01 +0200] "GET /40 HTTP/1.1" 200 117600 "-" "-" 82.114.62.14 - - [13/Sep/2012:15:17:01 +0200] "GET /34 HTTP/1.1" 200 60660 "-" "-" Any hints are welcome. I have no clue what's going wrong there :(

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• Is Perl's flip-flop operator bugged? It has global state, how can I reset it?

  - by Evan Carroll

  I'm dismayed. Ok, so this was probably the most fun perl bug I've ever found. Even today I'm learning new stuff about perl. Essentially, the flip-flop operator .. which returns false until the left-hand-side returns true, and then true until the right-hand-side returns false keep global state (or that is what I assume.) My question is can I reset it, (perhaps this would be a good addition to perl4-esque hardly ever used reset())? Or, is there no way to use this operator safely? I also don't see this (the global context bit) documented anywhere in perldoc perlop is this a mistake? Code use feature ':5.10'; use strict; use warnings; sub search { my $arr = shift; grep { !( /start/ .. /never_exist/ ) } @$arr; } my @foo = qw/foo bar start baz end quz quz/; my @bar = qw/foo bar start baz end quz quz/; say 'first shot - foo'; say for search \@foo; say 'second shot - bar'; say for search \@bar; Spoiler $ perl test.pl first shot foo bar second shot

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• "multiply frog enemy" timer and array AS3

  - by VideoDnd

  How can I use the counter value to multiply the frogs in the array? My counter goes from 0-100. I want to prove that I can increment the enemies using a counter. EXPLAINED BETTER I have 10 frogs in an array. I want to use a timer to add 10 more frogs on each iteration of the TimerEvent.TIMER firing. //currentCount var timer:Timer = new Timer(1000, 50); timer.addEventListener(TimerEvent.TIMER, countdown); timer.start(); function countdown(event:TimerEvent) { // myText.text = String(0 + timer.currentCount); } //Creates 10 enemies "I want enemies to multiply 0-100" var enemyArray:Array = new Array(); for (var i:int = 0; i < 10; i++) { var noname:FrogClass = new FrogClass(); noname.x = i*10; //this will just assign some different x and y value depending on i. noname.y = i*11; enemyArray.push(noname); //put the enemy into the array addChild(noname); //puts it on the stage } SYMBOL PROPERTIES NAME "noname" CLASS "FrogClass" WHY I need specific examples using strings and arrays, because I'm stuck in a learning curve. Stupid examples are more fun!

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• subtotals in columns usind reshape2 in R

  - by user1043144

  I have spent some time now learning RESHAPE2 and plyr but I still do not get it. This time I have a problem with (a) subtotals and (b) passing different aggregate functions . Here an example using data from the excellent tutorial on the blog of mrdwab http://news.mrdwab.com/ # libraries library(plyr) library(reshape2) # get data and add few more variables book.sales = read.csv("http://news.mrdwab.com/data-booksales") book.sales$Stock = book.sales$Quantity + 10 book.sales$SubjCat[(book.sales$Subject == 'Economics') | (book.sales$Subject == 'Management') ] <- '1_EconSciences' book.sales$SubjCat[book.sales$Subject %in% c('Anthropology', 'Politics', 'Sociology') ] <- '2_SocSciences' book.sales$SubjCat[book.sales$Subject %in% c('Communication', 'Fiction', 'History', 'Research', 'Statistics') ] <- '3_other' # to get to my starting dataframe (close to the project I am working on) book.sales1 <- ddply(book.sales, c('Region', 'Representative', 'SubjCat', 'Subject', 'Publisher'), summarize, Stock = sum(Stock), Sold = sum(Quantity), Ratio = round((100 * sum(Quantity)/ sum(Stock)), digits = 1)) #melt it m.book.sales = melt(data = book.sales1, id.vars = c('Region', 'Representative', 'SubjCat', 'Subject', 'Publisher'), measured.vars = c('Stock', 'Sold', 'Ratio')) # cast it Tab1 <- dcast(data = m.book.sales, formula = Region + Representative ~ Publisher + variable, fun.aggregate = sum, margins = c('Region', 'Representative')) Now my questions : I have been able to add the subtotals in rows. But is it possible also to add margins in the columns. Say for example, Totals of Stock for one Publisher ? Sorry I meant to say example total sold for all publishers There is a problem with the columns with “ratio”. How can I get “mean” instead of “sum” for this variable ? P.S: I have seen some examples using reshape. Will you recommend to use it instead of reshape2 (which seems not to include the functionalities of two functions).

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• Optimize CUDA with Thrust in a loop

  - by macs

  Given the following piece of code, generating a kind of code dictionary with CUDA using thrust (C++ template library for CUDA): thrust::device_vector<float> dCodes(codes->begin(), codes->end()); thrust::device_vector<int> dCounts(counts->begin(), counts->end()); thrust::device_vector<int> newCounts(counts->size()); for (int i = 0; i < dCodes.size(); i++) { float code = dCodes[i]; int count = thrust::count(dCodes.begin(), dCodes.end(), code); newCounts[i] = dCounts[i] + count; //Had we already a count in one of the last runs? if (dCounts[i] > 0) { newCounts[i]--; } //Remove thrust::detail::normal_iterator<thrust::device_ptr<float> > newEnd = thrust::remove(dCodes.begin()+i+1, dCodes.end(), code); int dist = thrust::distance(dCodes.begin(), newEnd); dCodes.resize(dist); newCounts.resize(dist); } codes->resize(dCodes.size()); counts->resize(newCounts.size()); thrust::copy(dCodes.begin(), dCodes.end(), codes->begin()); thrust::copy(newCounts.begin(), newCounts.end(), counts->begin()); The problem is, that i've noticed multiple copies of 4 bytes, by using CUDA visual profiler. IMO this is generated by The loop counter i float code, int count and dist Every access to i and the variables noted above This seems to slow down everything (sequential copying of 4 bytes is no fun...). So, how i'm telling thrust, that these variables shall be handled on the device? Or are they already? Using thrust::device_ptr seems not sufficient for me, because i'm not sure whether the for loop around runs on host or on device (which could also be another reason for the slowliness).

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• Modifying my website to allow anonymous comments

  - by David

  I write the code for my own website as an educational/fun exercise. Right now part of the website is a blog (like every other site out there :-/) which supports the usual basic blog features, including commenting on posts. But I only have comments enabled for logged-in users; I want to alter the code to allow anonymous comments - that is, I want to allow people to post comments without first creating a user account on my site, although there will still be some sort of authentication involved to prevent spam. Question: what information should I save for anonymous comments? I'm thinking at least display name and email address (for displaying a Gravatar), and probably website URL because I eventually want to accept OpenID as well, but would anything else make sense? Other question: how should I modify the database to store this information? The schema I have for the comment table is currently comment_id smallint(5) // The unique comment ID post_id smallint(5) // The ID of the post the comment was made on user_id smallint(5) // The ID of the user account who made the comment comment_subject varchar(128) comment_date timestamp comment_text text Should I add additional fields for name, email address, etc. to the comment table? (seems like a bad idea) Create a new "anonymous users" table? (and if so, how to keep anonymous user ids from conflicting with regular user ids) Or create fake user accounts for anonymous users in my existing users table? Part of what's making this tricky is that if someone tries to post an anonymous comment using an email address (or OpenID) that's already associated with an account on my site, I'd like to catch that and prompt them to log in.

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