Coding R

Presentation on Building R Packages

Last week I gave a presentation to the Melbourne R User Group on Building R Packages. The talk covered a simple package example, and an example of interfacing R with native code. The slides are here:


The R community in Melbourne (and Australia in general) is exploding, and it was great to see so many people from different backgrounds there. Looking forward to the next event!


Deducing the JDK Version of a .jar File

Here is a little script that uses Pyton to examine the contents of a jar file (or specifically the first .class file it comes across) and then reads the major version byte and maps it to a JDk version. May be useful if you have a bunch of jars compiled by different JDKs and want to figure out which is which.

[sourcecode language=”python”]#!/usr/bin/python

import zipfile
import sys
import re


for arg in sys.argv[1:]:
print ‘%s:’ % arg,
file=zipfile.ZipFile(arg, "r")

for entry in file.filelist:
bytes =
if maj_version==45:
print "JDK 1.1"
elif maj_version==46:
print "JDK 1.2"
elif maj_version==47:
print "JDK 1.3"
elif maj_version==48:
print "JDK 1.4"
elif maj_version==49:
print "JDK 5.0"
elif maj_version==50:
print "JDK 6.0"