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R to JSON for D3.js and Protovis
D3.js and Protovis use the file format JSON to hold input data. In particular, the most natural format is an array of JSON objects, such as [ { "Petal.Width" : 0.2, "Species" : "setosa" }, {...
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Rotated EPS from R in LaTeX
When it comes to figures in LaTeX, I usually generate figures in pdf format and use pdflatex to compile LaTeX with the pdf figures included. But sometimes a conference or a journal only accept figures...
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Comparing Dashboard Software: Part 1 (Filled Map)
Tableau Filled map is not supported by default in the current version of Tableau (6.1, see this post in the Tableau). However, it can be implemented through the Polygon Mark (see for example here). The...
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Resolving contradictory gender information
In biomedical data analysis, it is conventional to standardize the quantity of interest by age and gender. When the data is the result of merging multiple sources, some subjects of interest may have...
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When did C-section get popular?
C-section birth has a long history. But when did it get really popular? I generated this simple plot comparing the number births on a weekday and the number on a Saturday or Sunday. We can infer that...
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How to create CMYK images for journal publications?
Many journals require color figures to be in CMYK format. If you are not doing this over and over again, here is a quick and dirty way to do it, assuming that you are a Windows user. 1. Create your RGB...
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How to tell if the R session you are running is 64 bit or 32 bit?
Under Windows, here is a simple hack to find out whether you are running a 64 bit or 32 bit R. Type the command version in the prompt. If you see arch x86_64, then it is 64 bit. Otherwise, it...
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Circumvent Skype’s unable to add contact problem
In my workplace, the internet connection is through a proxy server. With Skype, I was able to talk to people in my contact list, but I was not able to add new contact. The problem and some solutions...
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Similar functions in R and Matlab
Although R and Matlab have many similarities, switching between the two languages is not always easy. Below is a lookup table that hopefully will make the process easier. Matlab R Note size dim find...
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Lightweight http daemons for Windows and Mac
As a Dropbox user, I often need to start a web server from a non-standard root folder location. Under Windows, I have been using Mongoose and loves it. Mongoose is a single .exe file that can be put...
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Estimating the intensity of ward admission and its effect on emergency...
Abstract Emergency department access block is an urgent problem faced by many public hospitals today. When access block occurs, patients in need of acute care cannot access inpatient wards within an...
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Rank 1 update to Cholesky factorization in R
Rank 1 update can be achieved in Matlab with the built-in function cholupdate(). More details about the function can be found here: http://www.mathworks.com.au/help/matlab/ref/cholupdate.html In R, the...
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Override a non-generic method in S3 OOP system
In R OOP, you can override a generic method for your custom class. For example, you can define print() and plot() methods for an class Foo. It is also easy to overrisk a non-generic method if you use...
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Detecting contaminated birthdates using generalized additive models
Background Erroneous patient birthdates are common in health databases. Detection of these errors usually involves manual verification, which can be resource intensive and impractical. By identifying a...
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