To use GnuplotRB gem with iRuby you need to install them both.
iRuby installation is covered in its README. It also covers installation of iPython and other dependecies.
GnuplotRB gem installation covered in README too.
List of notebooks
Embedding plots into iRuby
Using GnuplotRB inside iRuby notebooks is covered in:
2D and 3D plots
GnuplotRB is capable to plot vast range of plots from histograms to 3D heatmaps. Gem's repository contains examples of several plot types:
GnuplotRB may take data in Ruby container or in a file. Supported containers for now are Arrays, Daru::Vector and Daru::DataFrame. When data given in file, GnuplotRB pass filename to Gnuplot without reading the file into memory.
Examples of using different datasources:
You can not only plot several datasets in single coordinate system but place several coordinate systems on a canvas.
It's possible to use several plots (Plot, Splot or Multiplot objects) to create gif animation.
Fitting data with formula
GnuplotRB also may be used to fit some data with given math formula.