It turned out I have to do the following steps
- go to https://www.dropbox.com/s/rpn6yersv06tttz/gnuplot-4.2.5-i386.dmg
- download the gnuplot-4.2.5-i386.dmg
- open the resulting DMG file
- open the gnuplot-4.2.3 DMG the Extras folder
- drop Gnuplot.app into your applications folder
- go to /usr/bin in terminal and do
- $ sudo ln -sf "/Applications/Gnuplot.app/Contents/Resources/bin/ gnuplot"
You will be prompted to install X11 if you haven't done so, but after that if you run sample line like
python easy.py svmguide1 svmguide1.t
it should work. The sample files can be downloaded at http://www.csie.ntu.edu.tw/~cjlin/libsvmtools/datasets/binary.html#svmguide1
references: http://www.csie.ntu.edu.tw/~cjlin/papers/guide/guide.pdf