Blog Archives

Generate Distinct Colors

June 16, 2014
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Generate Distinct Colors

When plot with R (or some other software), it doesn’t bother you a lot for choosing colors if you have only several data series. For example, if I want to create a figure for 5 data series, I can choose red, green, dark green, blue and black. But what if I need to create a figure having 100 data...

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A Shiny-app Serves as Shiny-server Load Balancer

April 30, 2014
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The Shiny-app on open-source edition Shiny-server has only one concurrent, which means it can run only for one user at a time point. But it can host multiple Shiny-apps, which can run synchronously. So, if we create severl Shiny-apps with different names but same function, then we can let more users use our service at same time. But users...

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Automatically Scrape Flight Ticket Data Using R and Phantomjs

April 30, 2014
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I used to scrape static web pages with the R package RCurl. It’s a great package! When it comes to dynamic web pages, RCurl comes to be difficult to set up (actually, I never get it works). Then I met Phantomjs. PhantomJS is a headless WebKit scriptable with a JavaScript API. It has fast and native support for...

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Set Up Shiny-server on www.digitalocean.com

April 23, 2014
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Set Up Shiny-server on www.digitalocean.com

RStudio supplies several servers for hosting user’s apps, e.g. http://www.shinyapps.io/, http://spark.rstudio.com, http://glimmer.rstudio.com. Thanks a lot to RStudio who has contributed many excellent R libraries! I want to set my shiny-server on a virtual private server (VPS), because I have some other tasks and I feel a VPS is more stable than the PC under my desk.

Shiny-server System Performance Monitoring for Open Source Edition

April 9, 2014
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Shiny-server System Performance Monitoring for Open Source Edition

If you have deployed your Shiny-app on internet, you may curious about: how many users are using my app? Is the server powerful enough for hosting the app? You can get answers through the Server monitoring feature if you are using the Professional edition of Shiny server. What if we are using the Open source edition? Officially, there...

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Shiny-server Open Source Edition: Solution for CPU Bound Apps

March 19, 2014
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Shiny-server Open Source Edition: Solution for CPU Bound Apps

Shiny-server integrates the statistic power of R with web, convenients the statistical analysis through web. Users can do complecate statistical anlysis through their web browsers. However, most of statistical analysis of R are CPU bound computation, that means CPU utilization is high, perhaps at 100% for many seconds. This leads to the problem of thread blocking: if one user...

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Encrypt user’s password with md5 for you Shiny-app

February 14, 2014
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In a previous blog, I post a simple authentication method for Shiny-app, and received several comments mainly concerning that I should encrypt user password. I agree, user’s password can be intercepted when it was transferring. To secure users’ personal information, I think we should consider both server and client sides. Your server could be hacked and...

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Turn your Mac into a server for sharing photos

February 11, 2014
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Turn your Mac into a server for sharing photos

A month ago, I attended a friend’s wedding as a photographer (I am not good at shooting, just have a not so bad camera). I took more than 1000 pictures in high quality format. Later, I relized to share them with the guests attended wedding is a challenge: I need to go through every picture to identify if it...

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Who Touched My Shiny-app?

February 11, 2014
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When we created a Shiny-app, deployed it on a server and open it to public, we must have interesting of who visited our app, and if possible, where they from and what they have done. To achieve this, we need a user behavior tracking feature if we are not using the commercial version: Shiny-server pro. I wrote a JavaScript...

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Add ‘Calculation In Process’ Indicator for Shiny Application

January 3, 2014
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A Calculation in process busy indicator for shiny application is useful especially for the application that take long time to calculate result. I used to developed an application do model fitting which need more than 10 seconds! Users may lose their patience if the application doesn’t response after several seconds! One solution is add a process bar,...

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