Kaleidoscope IIIb (useR! 2011)
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O. Mersmann – The microbenchmark package
Slides and code (link).
SURGEON GENERAL’s WARNING: Microbenchmarks can lead to a distorted view of reality and massive loss of productivity
For a higher-order benchmarking package check out the rbenchmark package on R (suggestion from the speaker).
Why do we need micro-benchmarking? A simple example showed that it is currently very difficult to benchmark 1+1 and f= function() NULL using system.time. Microbenchmark has a very simple interface. Unlike system.time, MB measures the times of each individual function call. Produces summary statistics and plots.
How does microbenchmark() work?
- Linux:
clock_getttime(), gethrtime(); - MAC:
mach_timebase_info(); - Windows:
QueryPerformanceCounter(), QueryPerformanceFrequency()
Challenges:
- Precision of clock is unknown: clock could drift, timing might be zero, might observe discrete values;
- Clock only measures elapsed time. Some of this time may not actually be the R process.
Countermeasures to these problems include configurable CPU warm-up phase, configurable order of execution, warning if timings underflow. There are problems with MacOS X and Windows XP.
Planned features:
- More plotting functions;
- Possibly use OS API;
- Better diagnostic messages;
- Estimate clock granularity.
Paul Murrell – Vector image processing
Problem: convert a pretty pdf map into an interactive SVG document.
PDF -> R -> SVG
Discussion of recent improvements to the core R graphics engine and grImport. Using the svg would produce a static svg. However, the gridSVG produces an interactive SVG. Use
grid.animate, .garnish, .hyperlink, .script to make the picture interactive.Looks like a very nice package.
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