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  • How can I superimpose modified loess lines on a ggplot2 qplot?

    - by briandk
    Background Right now, I'm creating a multiple-predictor linear model and generating diagnostic plots to assess regression assumptions. (It's for a multiple regression analysis stats class that I'm loving at the moment :-) My textbook (Cohen, Cohen, West, and Aiken 2003) recommends plotting each predictor against the residuals to make sure that: The residuals don't systematically covary with the predictor The residuals are homoscedastic with respect to each predictor in the model On point (2), my textbook has this to say: Some statistical packages allow the analyst to plot lowess fit lines at the mean of the residuals (0-line), 1 standard deviation above the mean, and 1 standard deviation below the mean of the residuals....In the present case {their example}, the two lines {mean + 1sd and mean - 1sd} remain roughly parallel to the lowess {0} line, consistent with the interpretation that the variance of the residuals does not change as a function of X. (p. 131) How can I modify loess lines? I know how to generate a scatterplot with a "0-line,": # First, I'll make a simple linear model and get its diagnostic stats library(ggplot2) data(cars) mod <- fortify(lm(speed ~ dist, data = cars)) attach(mod) str(mod) # Now I want to make sure the residuals are homoscedastic qplot (x = dist, y = .resid, data = mod) + geom_smooth(se = FALSE) # "se = FALSE" Removes the standard error bands But does anyone know how I can use ggplot2 and qplot to generate plots where the 0-line, "mean + 1sd" AND "mean - 1sd" lines would be superimposed? Is that a weird/complex question to be asking?

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  • Favorite Programmer Quotes…

    - by SGWellens
      "A computer once beat me at chess, but it was no match for me at kick boxing." — Emo Philips   "There are only 10 types of people in the world, those who understand binary and those who don't. " – Unknown.   "Premature optimization is the root of all evil." — Donald Knuth   "I should have become a doctor; then I could bury my mistakes." — Unknown   "Code softly and carry a large backup thumb drive." — Me   "Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live." — Martin Golding   "DDE…the protocol from hell"— Charles Petzold   "Just because a thing is new don't mean that it's better" — Will Rogers   "The mark of a mature programmer is willingness to throw out code you spent time on when you realize it's pointless." — Bram Cohen   "A good programmer is someone who looks both ways before crossing a one-way street." — Doug Linder   "The early bird may get the worm but it's the second mouse that gets the cheese." — Unknown   I hope someone finds this amusing. Steve Wellens CodeProject

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  • How to use the Response from PHP in Objective-C?

    - by iMohammad
    I've managed to post and get datas from PHP thru objective-c. However, the response from the server looks like the following: ["ARC101","ARC112","ARC124","ARC203","ARC222","ARC251","ARC281","ARC305","ARC314","ARC344","ARC353","ARC363","ARC408","ARC416","ARC426","ARC482"] And, some responses could be more complicated like the following: [{"Code":"ARC101","Title":"Design Studio-I: Design Princi","Instructor":"Mike Cohen","Activity":"LAB","Days":"MW","Room":"B01","Bldg":"19","Section":"1","StartTime":"1310","EndTime":"1550","CallNo":"20438","Priority":null,"Open":"Open","HasAct":false,"CodeAct":null,"TitleAct":null,"InstructorAct":null] What would be your suggestion if I want to play with these datas? for example, putting them on a table ,etc. Thanks in Advance!

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  • New January 2013 Release of the Ajax Control Toolkit

    - by Stephen.Walther
    I am super excited to announce the January 2013 release of the Ajax Control Toolkit! I have one word to describe this release and that word is “Charts” – we’ve added lots of great new chart controls to the Ajax Control Toolkit. You can download the new release directly from http://AjaxControlToolkit.CodePlex.com – or, just fire the following command from the Visual Studio Library Package Manager Console Window (NuGet): Install-Package AjaxControlToolkit You also can view the new chart controls by visiting the “live” Ajax Control Toolkit Sample Site. 5 New Ajax Control Toolkit Chart Controls The Ajax Control Toolkit contains five new chart controls: the AreaChart, BarChart, BubbleChart, LineChart, and PieChart controls. Here is a sample of each of the controls: AreaChart: BarChart: BubbleChart: LineChart: PieChart: We realize that people love to customize the appearance of their charts so all of the chart controls include properties such as color properties. The chart controls render the chart on the browser using SVG. The chart controls are compatible with any browser which supports SVG including Internet Explorer 9 and new and recent versions of Google Chrome, Mozilla Firefox, and Apple Safari. (If you attempt to display a chart on a browser which does not support SVG then you won’t get an error – you just won’t get anything). Updates to the HTML Sanitizer If you are using the HtmlEditorExtender on a public-facing website then it is really important that you enable the HTML Sanitizer to prevent Cross-Site Scripting (XSS) attacks. The HtmlEditorExtender uses the HTML Sanitizer by default. The HTML Sanitizer strips out any suspicious content (like JavaScript code and CSS expressions) from the HTML submitted with the HtmlEditorExtender. We followed the recommendations of OWASP and ha.ckers.org to identify suspicious content. We updated the HTML Sanitizer with this release to protect against new types of XSS attacks. The HTML Sanitizer now has over 220 unit tests. The Ajax Control Toolkit team would like to thank Gil Cohen who helped us identify and block additional XSS attacks. Change in Ajax Control Toolkit Version Format We ran out of numbers. The Ajax Control Toolkit was first released way back in 2006. In previous releases, the version of the Ajax Control Toolkit followed the format: Release Year + Date. So, the previous release was 60919 where 6 represented the 6th release year and 0919 represent September 19. Unfortunately, the AssembyVersion attribute uses a UInt16 data type which has a maximum size of 65,534. The number 70123 is bigger than 65,534 so we had to change our version format with this release. Fortunately, the AssemblyVersion attribute actually accepts four UInt16 numbers so we used another one. This release of the Ajax Control Toolkit is officially version 7.0123. This new version format should work for another 65,000 years. And yes, I realize that 7.0123 is less than 60,919, but we ran out of numbers. Summary I hope that you find the chart controls included with this latest release of the Ajax Control Toolkit useful. Let me know if you use them in applications that you build. And, let me know if you run into any issues using the new chart controls. Next month, back to improving the File Upload control – more exciting stuff.

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  • Formal Languages, Inductive Proofs &amp; Regular Expressions

    - by MarkPearl
    So I am slogging away at my UNISA stuff. I have just finished doing the initial once non stop read through the first 11 chapters of my COS 201 Textbook - “Introduction to Computer Theory 2nd Edition” by Daniel Cohen. It has been an interesting couple of days, with familiar concepts coming up as well as some new territory. In this posting I am going to cover the first couple of chapters of the book. Let start with Formal Languages… What exactly is a formal language? Pretty much a no duh question for me but still a good one to ask – a formal language is a language that is defined in a precise mathematical way. Does that mean that the English language is a formal language? I would say no – and my main motivation for this is that one can have an English sentence that is correct grammatically that is also ambiguous. For example the ambiguous sentence: "I once shot an elephant in my pyjamas.” For this and possibly many other reasons that I am unaware of, English is termed a “Natural Language”. So why the importance of formal languages in computer science? Again a no duh question in my mind… If we want computers to be effective and useful tools then we need them to be able to evaluate a series of commands in some form of language that when interpreted by the device no confusion will exist as to what we were requesting. Imagine the mayhem that would exist if a computer misinterpreted a command to print a document and instead decided to delete it. So what is a Formal Language made up of… For my study purposes a language is made up of a finite alphabet. For a formal language to exist there needs to be a specification on the language that will describe whether a string of characters has membership in the language or not. There are two basic ways to do this: By a “machine” that will recognize strings of the language (e.g. Finite Automata). By a rule that describes how strings of a language can be formed (e.g. Regular Expressions). When we use the phrase “string of characters”, we can also be referring to a “word”. What is an Inductive Proof? So I am not to far into my textbook and of course it starts referring to proofs and different types. I have had to go through several different approaches of proofs in the past, but I can never remember their formal names , so when I saw “inductive proof” I thought to myself – what the heck is that? Google to the rescue… An inductive proof is like a normal proof but it employs a neat trick which allows you to prove a statement about an arbitrary number n by first proving it is true when n is 1 and then assuming it is true for n=k and showing it is true for n=k+1. The idea is that if you want to show that someone can climb to the nth floor of a fire escape, you need only show that you can climb the ladder up to the fire escape (n=1) and then show that you know how to climb the stairs from any level of the fire escape (n=k) to the next level (n=k+1). Does this sound like a form of recursion? No surprise then that in the same chapter they deal with recursive definitions. An example of a recursive definition for the language EVEN would the 3 rules below: 2 is in EVEN If x is in EVEN then so is x+2 The only elements in the set EVEN are those that be produced by the rules above. Nothing to exciting… So if a definition for a language is done recursively, then it makes sense that the language can be proved using induction. Regular Expressions So I am wondering to myself what use is this all – in fact – I find this the biggest challenge to any university material is that it is quite hard to find the immediate practical applications of some theory in real life stuff. How great was my joy when I suddenly saw the word regular expression being introduced. I had been introduced to regular expressions on Stack Overflow where I was trying to recognize if some text measurement put in by a user was in a valid form or not. For instance, the imperial system of measurement where you have feet and inches can be represented in so many different ways. I had eventually turned to regular expressions as an easy way to check if my parser could correctly parse the text or not and convert it to a normalize measurement. So some rules about languages and regular expressions… Any finite language can be represented by at least one if not more regular expressions A regular expressions is almost a rule syntax for expressing how regular languages can be formed regular expressions are cool For a regular expression to be valid for a language it must be able to generate all the words in the language and no other words. This is important. It doesn’t help me if my regular expression parses 100% of my measurement texts but also lets one or two invalid texts to pass as well. Okay, so this posting jumps around a bit – but introduces some very basic fundamentals for the subject which will be built on in later postings… Time to go and do some practical examples now…

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  • SQL Saturday #44 Huntington Beach Recap

    What a great day. It was long and tiring, but rewarding in so many ways. On Sunday morning, I was driving home and I decided to take the Pacific Coast Highway from Huntington Beach.  It was a great chance to exhale and just enjoy the sun and smells of the beach (I really love SoCal sometimes). And for future reference for all you speakers, the beach and ocean are only 5 minutes from the SQL Saturday location.  I just could help noticing also the shocking number of high priced cars on the road (4 Bentleys, 3 Ferraris, 1 Aston Martins, 3 Maserati, 1 Rolls Royce, and 2 Lamborghinis).  It made me think about this: Price of all those cars: $ 150,000+.  Impacting the ability of people to learn: Priceless.  We have positively impacted the education, knowledge, capabilities of not only our attendees, but also all of their companies and people they might help as well.  That is just staggering and something to be immensely proud of. To all of my fellow community leaders, I salute you. So lets talk about the event Overall We had over 220 people register for the event and had 180+ people attend the event. I was shooting for the magical 200 number, but I guess it just gives us more motivation to make it even bigger and better next time. We had a few snags along the way, but what event doesnt, but I think everything turned out great. I did not hear any negative comments and heard lots of positive comments along with people asking when the next one is going to be (More on that later). Location- Golden West College We could not have asked for a better partner for the event. Herb Cohen from Golden West College was the wizard behind the curtains. From the beginning, he was our advocate to the GWC Board and was instrumental in getting our event approved. The day off, Herb was a HUGE help getting any and all logistics that we needed taken care of. In the craziness of the early morning registration crush it was a big help knowing that he and Bret Stateham (Blog | Twitter) were taking care of testing projectors in all the rooms. Anything we needed he was there and was even proactive in getting some things that I had not even thought of (i.e. a dumpster for all of our garbage). I cannot thank Herb enough along with other members of the GWC staff including Minnie Higgins of the Career and Technical Education Division office, Jack Taylor, public safety, and Ron Pryor, Tech Services Support. And last, but not least, the Wireless on campus was absolutely FANTASTIC! Some lessons learned Unless you are a glutton for punishment, as I no doubt am, you most certainly want to give yourself more than six weeks to plan the event. I am lucky that I have a very understanding wife and had a wonderful set of co-coordinators helping me out. A big thanks goes out to Phil, Marlon (Blog | Twitter), Nitin (Twitter), Thomas (Blog | Twitter), Bret (Blog | Twitter), Ben, and Laurie. Thankfully, the sponsor and speaker community was hugely supportive and we were able to fill out the entire event with speakers and sponsors. I have to say that there is not a lot that I would change after this years event. There are obviously going to be some things that we can do better or differently next time, but overall I think it was a great event and I was more than happy with the response we received from the community. Sponsors We obviously could not have put together our event without our sponsors. So certainly have to show them some love. Platinum Sponsors Quest Software http://www.quest.com My Space http://www.myspace.com/ Gold Strategy Companion http://www.strategycompanion.com Silver Fusion-IO http://www.fusionio.com Bronze WestClinTech http://westclintech.com Professional Association For SQL Server http://www.sqlpass.org Attunity http://www.attunity.com Sharepoint 360 http://www.sharepoint360.com Some additional Thanks Andy Warren (Blog | Twitter) Always there to answer my question and help out when I had some issues or questions with the website. The amount of work that he and everyone else put into SQL Saturday is very amazing. What a great gift to the community! Einstein Bros. Bagels They were our Breakfast Vendor and arrived perfectly on time with yummy bagels, sweets and most importantly coffee. Luccis Deli (http://www.luccisdeli.com) Luccis was out Lunch Vendor. They were great to work with and the food was excellent. They worked with us to give us a great price. Heard lots of great comments about the lunches. Definitely not your ordinary box lunch. Moving Forward Unfortunately, the work does not end after the event. We have a few things to clear up such as surveys, sponsor stuff, presentations uploaded to the website, expense reimbursement, stuff like that. Hopefully, all that should be cleared up within the next couple weeks. After that as a group we are going to get together and decide what our next steps are. We definitely want to keep some of the momentum that we are building as a SQL Community and channel that into future SQL Saturdays and other types of community events. In the meantime, for additional training be sure to check out your local User Group and PASS. San Diego SQL Server Users Group ( http://www.sdsqlug.org/home/index.cfm ) Orange County SQL Server Users Group ( http://www.sqloc.com/ ) L.A. SQL Server Users Group ( http://www.sql.la/ ) SQL PASS ( http://www.sqlpass.org/ ) 24 Hours of PASS ( http://www.sqlpass.org/24hours/2010/ ) So stay tuned, there will be more events to come in SoCal!!Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Taking web sites offline for demonstration

    While working in software development in general, and in web development for a couple of customers it is quite common that it is necessary to provide a test bed where the client is able to get an image, or better said, a feeling for the visions and ideas you are talking about. Usually here at IOS Indian Ocean Software Ltd. we set up a demo web site on one of our staging servers, and provide credentials to the customer to access and review our progress and work ad hoc. This gives us the highest flexibility on both sides, as the test bed is simply online and available 24/7. We can update the structure, the UI and data at any time, and the client is able to view it as it suits best for her/him. Limited or lack of online connectivity But what is going to happen when your client is not capable to be online - no matter for what reasons; here are some more obvious ones: No internet connection (permanently or temporarily) Expensive connection, ie. mobile data package, stay at a hotel, etc. Presentation devices at an exhibition, ie. using tablets or iPads Being abroad for a certain time, and only occasionally online No network coverage, especially on mobile Bad infrastructure, like ie. in Third World countries Providing a catalogue on CD or USB pen drive Anyway, it doesn't matter really. We should be able to provide a solution for the circumstances of our customers. Presentation during an exhibition Recently, we had the following request from a customer: Is it possible to let us have a desktop version of ResortWork.co.uk that we can use for demo purposes at the forthcoming Ski Shows? It would allow us to let stand visitors browse the sites on an iPad to view jobs and training directory course listings. Yes, sure we can do that. Eventually, you might think why don't they simply use 3G enabled iPads for that purpose? As stated above, there might be several reasons for that - low coverage, expensive data packages, etc. Anyway, it is not a question on how to circumvent the request but to deliver a solution to that. Possible solutions... or not? We already did offline websites earlier, and even established complete mirrors of one or two web sites on our systems. There are actually several possibilities to handle this kind of request, and it mainly depends on the system or device where the offline site should be available on. Here, it is clearly expressed that we have to address this on an Apple iPad, well actually, I think that they'd like to use multiple devices during their exhibitions. Following is an overview of possible solutions depending on the technology or device in use, and how it can be done: Replication of source files and database The above mentioned web site is running on ASP.NET, IIS and SQL Server. In case that a laptop or slate runs a Windows OS, the easiest way would be to take a snapshot of the source files and database, and transfer them as local installation to those Windows machines. This approach would be fully operational on the local machine. Saving pages for offline usage This is actually a quite tedious job but still practicable for small web sites Tool based approach to 'harvest' the web site There quite some tools in the wild that could handle this job, namely wget, httrack, web copier, etc. Screenshots bundled as PDF document Not really... ;-) Creating screencast or video Simply navigate through your website and record your desktop session. Actually, we are using this kind of approach to track down difficult problems in order to see and understand exactly what the user was doing to cause an error. Of course, this list isn't complete and I'd love to get more of your ideas in the comments section below the article. Preparations for offline browsing The original website is dynamically and data-driven by ASP.NET, and looks like this: As we have to put the result onto iPads we are going to choose the tool-based approach to 'download' the whole web site for offline usage. Again, depending on the complexity of your web site you might have to check which of the applications produces the best results for you. My usual choice is to use wget but in this case, we run into problems related to the rewriting of hyperlinks. As a consequence of that we opted for using HTTrack. HTTrack comes in different flavours, like console application but also as either GUI (WinHTTrack on Windows) or Web client (WebHTTrack on Linux/Unix/BSD). Here's a brief description taken from the original website about HTTrack: HTTrack is a free (GPL, libre/free software) and easy-to-use offline browser utility. It allows you to download a World Wide Web site from the Internet to a local directory, building recursively all directories, getting HTML, images, and other files from the server to your computer. HTTrack arranges the original site's relative link-structure. Simply open a page of the "mirrored" website in your browser, and you can browse the site from link to link, as if you were viewing it online. And there is an extensive documentation for all options and switches online. General recommendation is to go through the HTTrack Users Guide By Fred Cohen. It covers all the initial steps you need to get up and running. Be aware that it will take quite some time to get all the necessary resources down to your machine. Actually, for our customer we run the tool directly on their web server to avoid unnecessary traffic and bandwidth. After a couple of runs and some additional fine-tuning - explicit inclusion or exclusion of various external linked web sites - we finally had a more or less complete offline version available. A very handsome feature of HTTrack is the error/warning log after completing the download. It contains some detailed information about errors that appeared on the pages and the links within the pages that have been processed. Error: "Bad Request" (400) at link www.resortwork.co.uk/job-details_Ski_hire:tech_or_mgr_or_driver_37854.aspx (from www.resortwork.co.uk/Jobs_A_to_Z.aspx)Error: "Not Found" (404) at link www.247recruit.net/images/applynow.png (from www.247recruit.net/css/global.css)Error: "Not Found" (404) at link www.247recruit.net/activate.html (from www.247recruit.net/247recruit_tefl_jobs_network.html) In our situation, we took the records of HTTP 400/404 errors and passed them to the web development department. Improvements are to be expected soon. ;-) Quality assurance on the full-featured desktop Unfortunately, the generated output of HTTrack was still incomplete but luckily there were only images missing. Being directly on the web server we simply copied the missing images from the original source folder into our offline version. After that, we created an archive and transferred the file securely to our local workspace for further review and checks. From that point on, it wasn't necessary to get any more files from the original web server, and we could focus ourselves completely on the process of browsing and navigating through the offline version to isolate visual differences and functional problems. As said, the original web site runs on ASP.NET Web Forms and uses Postback calls for interaction like search, pagination and partly for navigation. This is the main field of improving the offline experience. Of course, same as for standard web development it is advised to test with various browsers, and strangely we discovered that the offline version looked pretty good on Firefox, Chrome and Safari, but not in Internet Explorer. A quick look at the HTML source shed some light on this, and there are conditional CSS inclusions based on the user agent. HTTrack is not acting as Internet Explorer and so we didn't have the necessary overrides for this browser. Not problematic after all in our case, but you might have to pay attention to this and get the IE-specific files explicitly. And while having a view at the source code, we also found out that HTTrack actually modifies the generated HTML output. In several occasions we discovered that <div> elements were converted into <table> constructs for no obvious reason; even nested structures. Search 'e'nd destroy - sed (or Notepad++) to the rescue During our intensive root cause analysis for a couple of HTML/CSS problems that needed some extra attention it is very helpful to be familiar with any editor that allows search and replace over multiple files like, ie. sed - stream editor for filtering and transforming text on Linux or my personal favourite Notepad++ on Windows. This allowed us to quickly fix a lot of anchors with onclick attributes and Javascript code that was addressed to ASP.NET files instead of their generated HTML counterparts, like so: grep -lr -e '.aspx' * | xargs sed -e 's/.aspx/.html?/g' The additional question mark after the HTML extension helps to separate the query string from the actual target and solved all our missing hyperlinks very fast. The same can be done in Notepad++ on Windows, too. Just use the 'Replace in files' feature and you are settled. Especially, in combination with Regular Expressions (regex). Landscape of browsers Okay, after several runs of HTML/CSS code analysis, searching and replacing some strings in a pool of more than 4.000 files, we finally had a very good match of an offline browsing experience in Firefox and Chrome on Linux. Next, we transferred that modified set of files to a Windows 8 machine for review on Firefox, Chrome and Internet Explorer 7 to 10, and a Mac mini running Mac OS X 10.7 to check the output on Safari and again on Chrome. Besides IE, for reasons already mentioned above, the results were identical. And last but not least it was about to check web site on tablets. Please continue to read on the following articles: Taking web sites offline for demonstration on Galaxy Tablet Taking web sites offline for demonstration on iPad

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