Search Results

Search found 10295 results on 412 pages for 'rails beginner'.

Page 393/412 | < Previous Page | 389 390 391 392 393 394 395 396 397 398 399 400 | Next Page >

Architecture for database analytics

- by David Cournapeau

Hi, We have an architecture where we provide each customer Business Intelligence-like services for their website (internet merchant). Now, I need to analyze those data internally (for algorithmic improvement, performance tracking, etc...) and those are potentially quite heavy: we have up to millions of rows / customer / day, and I may want to know how many queries we had in the last month, weekly compared, etc... that is the order of billions entries if not more. The way it is currently done is quite standard: daily scripts which scan the databases, and generate big CSV files. I don't like this solutions for several reasons: as typical with those kinds of scripts, they fall into the write-once and never-touched-again category tracking things in "real-time" is necessary (we have separate toolset to query the last few hours ATM). this is slow and non-"agile" Although I have some experience in dealing with huge datasets for scientific usage, I am a complete beginner as far as traditional RDBM go. It seems that using column-oriented database for analytics could be a solution (the analytics don't need most of the data we have in the app database), but I would like to know what other options are available for this kind of issues.

Read the article
How to get started with embedded systems in the airline or submarine industries?

- by Jason

Hi, Not 100% sure how to frame this question but here goes... I currently work as a Rails developer but want to work on more substancial / "meaty" projects and have always been very interested in embedded systems, especially systems that run on aircraft and especially submarines.....I know strange combination. I have been doing some searching & found lockheed martin produces a lot of underwater systems for various navys around the world e.g. http://www.naval-technology.com/projects/nssn/ However, there is very little information about what software is used within these systems, what OS's they use or anything else "technical", presume there is a lot of C / C++ involved but that is just a guess... so its hard to know where to even begin learning what is required to potential work in these areas. Just wondering if anyone has any experiance working with or more information about embeddeed systems in either the airline (onboard flight systems) or especially submarine systems? Thanks!

Read the article
Ruby : UTF-8 IO

- by subtenante

I use ruby 1.8.7. I try to parse some text files containing greek sentences, encoded in UTF-8. (I can't much paste here sample files, because they are subject to copyright. Really just some greek text encoded in UTF-8.) I want, for each file, to parse the file, extract all the words, and make a list of each new word found in this file. All that saved to one big index file. Here is my code : #!/usr/bin/ruby -KU def prepare_line(l) l.gsub(/^\s*[ST]\d+\s*:\s*|\s+$|\(\d+\)\s*/u, "") end def tokenize(l) l.split /['·.;!:\s]+/u end $dict = {} $cpt = 0 $out = File.new 'out.txt', 'w' def lesson(file) $cpt = $cpt + 1 file.readlines.each do |l| $out.puts l l = prepare_line l tokenize(l).each do |t| unless $dict[t] $dict[t] = $cpt $out.puts " #{t}\n" end end end end Dir.new('etc/').each do |filename| f = File.new("etc/#{filename}") unless File.directory? f lesson f end end Here is part of my output : ?@???†?†?????????? ?...[snip very long hangul/hanzi mishmash]... ????????†? ???N2 : ?e?te?? (2) µ???µa (Note that the puts l part seems to work fine, at the end of the given output line.) Any idea what is wrong with my code ? (General comments about ruby idioms I could use are very welcome, I'm really a beginner.)

Read the article
little java help....

- by jona

Hi I am doing some practice problems and trying to print a diagonal line like the example below. I have writen the program you see below and I honestly dont understand what I am doing wrong. I m a java beginner and I cant see how to find the error. Example ( If you only see a straight line of stars...then imagine it diagonally....from top left to bottom right) * * * * * code: class Diagonal{ public static void main(String args[]) { int row, col; for(row = 1; row < 6; row++) { for(col = 1; col <= row; col++) { if(col==row){ System.out.print("*"); } else{ System.out.print(""); } System.out.println(); } } } } I am trying to learn for loops because they really confuse me. Another practice is to print a similar diagonal line but this time from right to left. I cant do that without getting this right however :( I believe they will be pretty similar? Above my reasining is this: As long as the column # is the same as the row number the print the line or otherwise leave a blank....what's wrong with how i did it? THANK YOU!

Read the article
How to develop for iphone application about "retrieving database file on web"?

- by coverboy

Hi...all experts! I'm a newbie to iphone developer. Well, currently, I'm developing iphone for Location Based Service. That application need to have these functions. 1. hierarchical tree-view on navigation bar. 2. list up page 3. detail page for example, Let's say. I have top category like "Restaurant, Hotel, Gift Shop" Second level "New York, LA, London,....." Third Level displays all Data with 1 photo. Fourth Level displays Detail of that "Restaurant or Hotel, Gift shop, ..." So, My Only Interest is "How to retrieve the data from remote database server. not using iphone local one." Because, that locations, and shops should be updated frequently, (you know some shops closed, new shops opens.) So, till now, I figured out that using XML to retrieve data. However, using XML is the most effective way to implement? Is there any other way to accomplish this work? You know, transferring XML data via 3G Network is really slow. XML file have more bytes than plist file. I'm currently a beginner of iphone development. So, please help me find a right way!! And, one more question, if I use xml way. Is it possible to Paging? (First page 10 lists up, below that more button...) well, you might guess each category have hundreds of shops!!

Read the article
Override transparency color when converting transparent PNG to JPG

- by Alexander Malfait

I'm using Dragonfly to generate thumbnail images in a Rails app. I'm serving all picture images as JPG's. Now the client is uploading transparent PNG files, like this one: http://www.ibanez.co.jp/products/images/eg2010/ART120_TRF_12_02.png Dragonfly uses RMagick to convert these images to JPG. The problem is that it converts the PNG images to JPG with a black background, and my site's design requires a white background. I've tried to override it like this: encoded_image = Magick::Image.from_blob(image.data).first if encoded_image.format.downcase == format image # do nothing else encoded_image.format = format encoded_image.background_color = "white" encoded_image.transparent_color = "white" encoded_image.to_blob end But the produced JPG images still contain a black background. Does anyone know how to beat RMagick into using a white background when converting the transparent layer? I know I could just serve as PNG, but then the images are 10 times as large, and the site is already pretty bandwidth heavy.

Read the article
converting numbers into alphabets.

- by Nina

Hi! i want to convert number into alphabets using javascript e.g. 01=n, 02=i 03=n,04=a and when someone enters the numbers:01020304 in the form he will get like this: nina. or whatever he enters it get replace with equivalent alphabets including spaces. i will be really thankful if you can provide full code including html form code as i am beginner. Thank you all for quick response. I have found this code in one site it converts alphabets into numbers, but code for converting numbers into alphabets isn't working. here is a code for converting alphabets into numbers: var i,j; var getc; var len; var num,alpha; num=new Array("01","02","03","04","05","06","07","08","09","10","11","12","13","14","15","16","17", "18","19","20","21","22","23","24","25","26","00","##","$$"); alpha=new Array("a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u"," v","w","x","y","z"," ",".",","); function encode() { len=document.f1.ta1.value.length; document.f1.ta2.value=""; for(i=0;i

Read the article
Help me to refactor this F# code to tail recursion

- by Kev

I write some code to learning F#. Here is a example: let nextPrime list= let rec loop n= match n with | _ when (list |> List.filter (fun x -> x <= ( n |> double |> sqrt |> int)) |> List.forall (fun x -> n % x <> 0)) -> n | _ -> loop (n+1) loop (List.max list + 1) let rec findPrimes num= match num with | 1 -> [2] | n -> let temp = findPrimes <| n-1 (nextPrime temp ) :: temp //find 10 primes findPrimes 10 |> printfn "%A" I'm very happy that it just works! I'm totally beginner to recursion Recursion is a wonderful thing. I think findPrimes is not efficient. Someone help me to refactor findPrimes to tail recursion if possible? BTW, is there some more efficient way to find first n primes?

Read the article
Grep expression with special file names

- by user2919185

i am a real beginner in csh/tcsh scripting and that's why i need your help. The problem is I have to go through some regular files in directories and find those files, that have their own name in its content. In the following piece of script is cycle in which I am going through paths and using grep to find the file's name in its content. What is surely correct is $something:q - is array of paths where i have to find files. The next variable is name in which is only name of current file. for example: /home/computer/text.txt (paths) and: text.txt (name) And my biggest problem is to find names of files in their content. It's quite difficult for me to write correct grep for this, cause the names of files and directories that i am passing through are mad. Here are some of them: /home/OS/pocitacove/testovaci_adresar/z/test4.pre_expertov/!_1 /home/OS/pocitacove/testovaci_adresar/z/test4.pre_expertov/dam/$user/:e/'/-r /home/OS/pocitacove/testovaci_adresar/z/test3/skusime/ taketo/ taketo /home/OS/pocitacove/testovaci_adresar/z/test4.pre_expertov/.-bla/.-bla/.a=b /home/OS/pocitacove/testovaci_adresar/z/test4.pre_expertov/.-bla/.-bla/@ /home/OS/pocitacove/testovaci_adresar/z/test4.pre_expertov/.-bla/.-bla/: /home/OS/pocitacove/testovaci_adresar/z/test4.pre_expertov/.-bla/.-bla/'ano' foreach paths ($something:q) set name = "$paths:t" @ number = (`grep -Ec "$name" "$paths"`) if ($number != 0) then echo -n "$paths " echo $number endif @ number = 0 end

Read the article
Performance difference in for loop condition?

- by CSharperWithJava

Hello all, I have a simple question that I am posing mostly for my curiousity. What are the differences between these two lines of code? (in C++) for(int i = 0; i < N, N > 0; i++) for(int i = 0; i < N && N > 0; i++) The selection of the conditions is completely arbitrary, I'm just interested in the differences between , and &&. I'm not a beginner to coding by any means, but I've never bothered with the comma operator. Are there performance/behavior differences or is it purely aesthetic? One last note, I know there are bigger performance fish to fry than a conditional operator, but I'm just curious. Indulge me. Edit Thanks for your answers. It turns out the code that prompted this question had misused the comma operator in the way I've described. I wondered what the difference was and why it wasn't a && operator, but it was just written incorrectly. I didn't think anything was wrong with it because it worked just fine. Thanks for straightening me out.

Read the article
jQuery Checkbox Error

- by Zack Fernandes

Hello, I am working on a jQuery-based todo list interface, and have hit a bit of a wall. The jQuery I am working with is a bit hacked together from various tutorials I have read, as I'm a bit of a beginner. $('#todo input:checkbox').click(function(){ var id = this.attr("value"); if(!$(this).is(":checked")) { alert("Starting."); $.ajax({ type: "GET", url: "/todos/check/"+id, success: function(){ alert("It worked.") } }); } }) This is the HTML I am using, <div id="todo"> <input type="checkbox" checked="yes" value="1"> Hello, world. <br /> </div> Any help on this would be greatly appreciated. For reference, thereason I have alerts in the jQuery is for debugging. The reason I can tell the code isn't working is because I am not getting these alerts. Thanks.

Read the article
How can I make a Twitter style alert stick to the top of the window?

- by Robert Robb

There is an excellent code example on how to make nice jQuery Twitter style alerts here: http://blog.codecrate.com/2009/10/twitter-style-alerts-in-rails.html $(function () { var alert = $('.alert'); if (alert.length > 0) { alert.show().animate({height: alert.outerHeight()}, 200); window.setTimeout(function() { alert.slideUp(); }, 3000); } }); However, one thing that the code doesn't include is functions to stick the alert div to the top of the window, no matter how far down the page the user has scrolled. I have found a few examples but nothing seems to play nice with this existing code. Any ideas?

Read the article
In plain English, what are Django generic views?

- by allyourcode

The first two paragraphs of this page explain that generic views are supposed to make my life easier, less monotonous, and make me more attractive to women (I made up that last one): http://docs.djangoproject.com/en/dev/topics/generic-views/#topics-generic-views I'm all for improving my life, but what do generic views actually do? It seems like lots of buzzwords are being thrown around, which confuse more than they explain. Are generic views similar to scaffolding in Ruby on Rails? The last bullet point in the intro seems to indicate this. Is that an accurate statement?

Read the article
Interchange structured data between Haskell and C

- by Eonil

First, I'm a Haskell beginner. I'm planning integrating Haskell into C for realtime game. Haskell does logic, C does rendering. To do this, I have to pass huge complexly structured data (game state) from/to each other for each tick (at least 30 times per second). So the passing data should be lightweight. This state data may laid on sequential space on memory. Both of Haskell and C parts should access every area of the states freely. In best case, the cost of passing data can be copying a pointer to a memory. In worst case, copying whole data with conversion. I'm reading Haskell's FFI(http://www.haskell.org/haskellwiki/FFICookBook#Working_with_structs) The Haskell code look specifying memory layout explicitly. I have a few questions. Can Haskell specify memory layout explicitly? (to be matched exactly with C struct) Is this real memory layout? Or any kind of conversion required? (performance penalty) If Q#2 is true, Any performance penalty when the memory layout specified explicitly? What's the syntax #{alignment foo}? Where can I find the document about this? If I want to pass huge data with best performance, how should I do that? *PS Explicit memory layout feature which I said is just C#'s [StructLayout] attribute. Which is specifying in-memory position and size explicitly. http://www.developerfusion.com/article/84519/mastering-structs-in-c/ I'm not sure Haskell has matching linguistic construct matching with fields of C struct.

Read the article
Correct way to safely store token/secret/etc from OAuth?

- by viatropos

I just started looking into OAuth and it looks really nice. I have oauth with twitter working in ruby right now. Now I'm wondering, what is the recommended safe way to store the responses in my local database and session? What should I store? Where should I store it? This example twitter-oauth-with-rails app stores a user.id in the session, and the user table has the token and secret. But that seems like it'd be really easy to hack and get the secret by just passing in a slew of test user ids, no?

Read the article
How to encrypt/decrypt a file in Java?

- by Petike

Hello, I am writing a Java application which can "encrypt" and consequently "decrypt" whatever binary file. I am just a beginner in the "cryptography" area so I would like to write a very simple application for the beginning. For reading the original file, I would probably use the java.io.FileInputStream class to get the "array of bytes" byte originalBytes[] of the file. Then I would probably use some very simple cipher, for example "shift up every byte by 1" and then I would get the "encrypted" bytes byte encryptedBytes[] and let's say that I would also set a "password" for it, for example "123456789". Next, when somebody wants to "decrypt" that file, he has to enter the password ("123456789") first and after that the file could be decrypted (thus "shift down every byte by 1") and consequently saved to the output file via java.io.FileOutputStream I am just wondering how to "store" the password information to the encrypted file so that the decrypting application knows if the entered password and the "real" password equals? Probably it would be silly to add the password (for example the ASCII ordinal numbers of the password letters) to the beginning of the file (before the encrypted data). So my main question is how to store the password information to the encrypted file?

Read the article
php and mysql listing databases and looping through results

- by Jacksta

Beginner help needed :) I am doign an example form a php book which lists tables in databases. I am getting an error on line 36: $db_list .= "$table_list"; <?php //connect to database $connection = mysql_connect("localhost", "admin_cantsayno", "cantsayno") or die(mysql_error()); //list databases $dbs = @mysql_list_dbs($connection) or die(mysql_error()); //start first bullet list $db_list = "<ul>"; $db_num = 0; //loop through results of functions while ($db_num < mysql_num_rows($dbs)) { //get database names and make each a list point $db_names[$db_num] = mysql_tablename($dbs, $db_num); $db_list .= "<li>$db_names[$db_num]"; //get table names and make another list $tables = @mysql_list_tables($db_names[$db_num]) or die(mysql_error()); $table_list = "<ul>"; $table_num = 0; //loop through results of function while ($table_num < mysql_num_rows($tables)){ //get table names and make each bullet point $table_names[$table_num] = mysql_tablename($tables, $table_num); $table_list .= "<li>$table_names[$table_num]"; $table_num++; } //close inner bullet list and increment number to continue $table_list .= "</ul>" $db_list .= "$table_list"; $db_num++; } //close outer bullet list $db_list .= "</ul>"; ?> <html> <head> <title>MySQL Tables</title> </head> <body> <p><strong>Data bases and tables on local host</strong></p> <? echo "$db_list"; ?> </body>

Read the article
Programmatically Download Image to Desktop from Remote App with Ruby?

- by viatropos

I was thinking about making a little crop/resize batch processor online, and wanted to know if there was a way for me to do the following: upload image and specify dimensions click "process" and app resizes image image downloads automatically to wherever it was I uploaded it (say from my desktop), but with a new name (based on the time for example). This would make it so I could host a free image processor that never stored any data other than tempfiles. Is that possible? Something like Rails' send_file method, but I'm using Sinatra and am looking for something in pure ruby.

Read the article
Which Stroustrup book should I use?

- by Chris Simmons

I'm a C# programmer that is looking to branch out. I'm bored of writing business software and want to start getting into graphics programming and games/simulators. So I figured, although writing that stuff isn't impossible in managed code, the "right" way to do that would be to look to C++, of course focussing on the language first, then getting into OpenGL or DirectX (or whatever). Way way back ('98? '99?) I had tried and failed to really grasp Stroustrup's The C++ Programming Language. I know that this book is often not recommended for the beginner. Anyway, I picked it back up (in a much more recent printing) and I'm actually getting it and enjoying it. I also have a copy of his textbook, Programming: Principles and Practice Using C++, which, as I understand it, is really geared toward teaching programming, not necessarily C++. I'm certainly not arrogant enough to claim I don't have anything more to learn about programming, data structures, algoriths, etc., however I'm not a novice there either. So my question is, with the goal of gaining the broader and more real-world-useful understanding of C++ and given my background, on which should I focus? The denser (as I perceive it) TCPPPL or the gentler Programming? EDIT: I thank everyone for the responses. However, I've got a personal choice here to make between these two books. Granted there are other very good books out there, but I'm already a good length into both of the books I mention and I'd like to finish one. So, can anyone respond on which would be the better and why? Time is not an issue; I'm not looking (at this point) at an "accelerated" read.

Read the article
In MongoDB, how can I replicate this simple query using map/reduce in ruby?

- by Matthew Rathbone

Hi, So using the regular MongoDB library in Ruby I have the following query to find average filesize across a set of 5001 documents: avg = 0 total = collection.count() Rails.logger.info "#{total} asset creation stats in the system" collection.find().each {|row| avg += (row["filesize"] * (1/total.to_f)) if row["filesize"]} Its pretty simple, so I'm trying to do the same using map/reduce as a learning exercise. This is what I came up with: map = 'function(){emit("filesizes", {size: this.filesize, num: 1});}' reduce = 'function(k, vals){ var result = {size: 0, num: 0}; for(var x in vals) { var new_total = result.num + vals[x].num; result.num = new_total result.size = result.size + (vals[x].size * (vals[x].num / new_total)); } return result; }' @results = collection.map_reduce(map, reduce) However the two queries come back with two different results! What am I doing wrong?

Read the article
Want to display a 3D model on the iPhone: how to get started?

- by JeremyReimer

I want to display and rotate a single 3D model, preferably textured, on the iPhone. Doesn't have to zoom in and out, or have a background, or anything. I have the following: an iPhone a MacBook the iPhone SDK Blender My knowledge base: I can make 3D models in various 3D programs (I'm most comfortable with 3D Studio Max, which I once took a course on, but I've used others) General knowledge of procedural programming from years ago (QuickBasic - I'm old!) Beginner's knowledge of object-oriented programming from going through simple Java and C# tutorials (Head Start C# book and my wife's intro to OOP course that used Java) I have managed to display a 3D textured model and spin it using a tutorial in C# I got off the net (I didn't just copy and paste, I understand basically how it works) and the XNA game development library, using Visual Studio on Windows. What I do not know: Much about Objective C Anything about OpenGL or OpenGL ES, which the iPhone apparently uses Anything about XCode My main problem is that I don't know where to start! All the iPhone books I found seem to be about creating GUI applications, not OpenGL apps. I found an OpenGL book but I don't know how much, if any, applies to iPhone development. And I find the Objective C syntax somewhat confusing, with the weird nested method naming, things like "id" that don't make sense, and the scary thought that I have to do manual memory management. Where is the best place to start? I couldn't find any tutorials for this sort of thing, but maybe my Google-Fu is weak. Or maybe I should start with learning Objective C? I know of books like Aaron Hillgrass', but I've also read that they are outdated and much of the sample code doesn't work on the iPhone SDK, plus it seems geared towards the Model-View-Controller paradigm which doesn't seem that suited for 3D apps. Basically I'm confused about what my first steps should be.

Read the article
How to install Zend Framework on Windows

- by sombe

"installing Zend Framework is so easy!!!!" yeah right... Ok I'm working with a beginner's book and the ONE thing that is not excessively detailed is the most important part: Installing the darn thing. After browsing the quickstart guide for hours, all it said was: "download Zend [...] add the include directory (bla bla) and YOU'RE DONE!" right, i'm done using Zend. Ok, not really, not yet anyway. I beg of you people, I wanna go to bed, please tell me how (in simple 6th grade detail) to install the framework. I've got the unzipped folder in my htdocs directory, and I placed zf.bat+zf.php in the htdocs root. What's next? thank you so much. EDIT: Thanks guys for all the answers. Unfortunately I haven't been able to work with this or find a good enough resource to explain it to me in plain english. It seems that this framework adheres more so to programmers than to beginners. I've since yesterday read a little on CakePHP and found that it was incredibly easy to install and tune. As oppose to Zend Framework, where I had to dig in my "environment variables", configure "httpd.conf" and almost tie the knot between my computer driver cables to just get it running, CakePHP has already allowed me to put together a nice newbie application. In conclusion, I very much appreciate all of your help. I hope someone else venturing on ZF will be more successful with it. Thanks!

Read the article
Create swipe controlled simple flipbook style animation in ObjC

- by eco_bach

Hi I am a beginner in Obj C development, though quite experienced (over 10 years) with other ECMAscript based languages and OOP development. I want to build a simple flipbook style animation, controlled through swiping motion. I'm sure extremely simple for any advanced ObjC coders. Can anyone with extensive ObjC-CocoaTouch experience give me some higher level recommendations? ie, 1 -general application design, should I start with a simple view based application, or navigation based or? 2 -should I use 3rd party animation frameworks such as Cocos2D, or stick with built in classes and methods? 3 -if using built in methods, classes, what is the recommended way of achieving a animation, that will be controlled via swipe and touch gestures? 4 -I want to eventually have multiple 'flipbooks' that I can 'instantly' swap with one another, ie to give the net effect of an object changing color, etc, but not sure how to approach this from a memory management point of view, related to #1 above Except for point 3 above, I'm not expecting any actual code examples. Just general guidelines to follow and perhaps, what are some next steps I should take in my goal as an ObjC code samurai.

Read the article
Stripes for Java Web Dev, is it worth learning ? Is it easier ? how it compared to Struts ?

- by cfontes

I am tired of Java web, and started to learn Ruby on Rails because of that, but I just found this Framework and it looks promessing... But I am not in the mood to study more Java, so I would like to know if this one is worth my time ( that would mean, less configuration and action mapping and so on) Is it better then Struts 2(WebWorks) ??? because those are way better then Struts 1 but still not a RoR. Spring MVC ? I would like a Hands On Opnion, not a specs compare. Thanks !

Read the article
Are there any issues with MySQL's i18n(indic language) support ?

- by anjanb

Hi All, We're evaluating MySQL and PostgreSQL for building our indic language web application which will use MySQL or PostgreSQL. One of my colleagues mentioned that MySQL had issues with i18n. I mostly come from the Oracle world and although I've played a lil with MySQL, I don't know enough to know that there are issues with its i18n support. Does anyone know issues with MySQL's i18n support and if PostgreSQL would be better placed for building an application with indic language support(kannada, telugu, tamil, etc) ? Just so you know, we're going to be using J2EE to build this application and we will be using JDBC drivers to access the DB. P.S : Will anything change if we were to use Rails to build the app instead of J2EE ? Thank you,

Read the article

< Previous Page | 389 390 391 392 393 394 395 396 397 398 399 400 | Next Page >