Javascript, visualization and statistics (Protovis and Jstat)

Last week I got faced with two very interesting libraries.

Protovis
Protovis uses JavaScript and SVG for web-native visualizations. Protovis composes custom views of data with simple marks such as bars and dots.

Unlike low-level graphics libraries that quickly become tedious for visualization, Protovis defines marks through dynamic properties that encode data, allowing inheritance, scales and layouts to simplify construction.

jStat

jStat is a statistical library written in JavaScript that allows you to perform advanced statistical operations without the need of a dedicated statistical language (i.e. MATLAB or R).

Read Write Web has also an article about other 20 JavaScript Libraries for Data Visualization

Comments

uSleep on windows (win32)

I am facing a terrible issue regarding timing on windows. Googling arround, I've found those infos: Using QueryPerformanceCounter and QueryPerformanceFrequency APIs in Dev-C++ ( http://yeohhs.blogspot.com/2005/08/using -queryperformancecounter-and_13.html ) QueryPerformanceCounter() vs. GetTickCount() http://www.delphifaq.com/faq/delphi_windows_API/f345.shtml How to time a block of code http://www.cryer.co.uk/brian/delphi/howto_time_code.htm And Results of some quick research on timing in Win32 http://www.geisswerks.com/ryan/FAQS/timing.html With that I'm trying to write something like a uSleep function for windows: # include<windows.h> void uSleep ( int waitTime){ __int64 time1 = 0, time2 = 0, sysFreq = 0; QueryPerformanceCounter((LARGE_INTEGER *)&time1); QueryPerformanceFrequency((LARGE_INTEGER *)&freq); do { QueryPerformanceCounter((LARGE_INTEGER *)&time2); // }while((((time2-time1)*1.0)/sysFreq)<waitTime); } while ( (time2-time1) <waitTime); } T

Soft body deformation

The wikipedia has a short entry on " Soft body dynamics " but it cites this interesting framework called SOFA. "SOFA [ 1 ] is an Open Source framework primarily targeted at real-time physical simulation , with an emphasis on medical simulation. It is mostly intended for the research community to help develop newer algorithms, but can also be used as an efficient prototyping tool or as a physics engine ." [1] It is also multi-platform. As soon as I have some test written, I will put some shots here. [1] SOFA (Simulation Open Framework Architecture). (2009, March 26). In Wikipedia, The Free Encyclopedia . Retrieved 14:01, May 7, 2009, from http://en.wikipedia.org/w/index.php?title=SOFA_(Simulation_Open_Framework_Architecture)&oldid=279736872

More trickery with gnuplot dumb terminal

In my post " Plotting memory usage on console " the chart doesn't pan the data. Now, using a named pipe, the effect got a little bit nicer. First, we have to run the memUsage.sh script to get a file filled with memory usage info: ./memUsage.sh > memUsage.dat & Then we have to create a named pipe: mkfifo pipe Now we have to run another process to tail only the last 64 lines from the memUsage.dat while [ 1 ]; do tail -64 memUsage.dat> pipe; done & And now we just have to plot the data from the pipe: watch -n 1 'gnuplot -e "set terminal dumb;p \"pipe\" with lines"' And that is it!

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