Python (http://www.python.org) is an open source scripting language that is versatile and easy to learn. Over the last years, Python has gained a lot of traction among the scientific community. The main scientific modules can be found at: http://www.SciPy.org
Like R dataframes, checkout pandas: http://pandas.pydata.org/
Python comes pre-installed with the major Unix-based distribution, including Mac OS X. If for any reason you need to install Python on a server without the sudo rights you can always refer to the following page:
The Mac OS X included version of Python may not be suitable for some tasks. Rather than tempering with that version, it’s generally better to install addition versions. For an example see the following: