R In a Nutshell cover image

Let us take an example (source: http://www.r-bloggers.com/stock-analysis-using-r/). The following code installs the quantmod package and then displays the stock of Apple along with Bollinger Bands (http://www.bollingerbands.com/).

install.packages("quantmod") # installs the package quantmod
library(quantmod) # loads the package
getSymbols("AAPL") # load Apple's data
chartSeries(AAPL) # Create financial charts
addBBands() # Add the Bollinger Bands.

The graph below was created using the steps above.

R In A Nutshell - Graph

One of the best parts of R is huge support of libraries for doing commercial grade statistics and the plots/graphs produced by R are of high quality.
Though I didn't get a chance to try it out, there is a package called RPy which is a Python interface to the R programming language. More details can be found here: http://rpy.sourceforge.net/

If you are mathematically inclined, definitely check this book out. Once you learn R, you can use it anywhere/anytime without ever paying a license fee.