Both R & Python should be measured based on their effectiveness in advanced analytics & data science. Initially, as a new comer in data science field we spend good amount of time to understand the pros and cons of these two. I too carried out this study solely for “self” to decide which tool should i pick to get in depth of data science. Eventually, i have started realizing that both (R & Python) has its space of mastery along with their broad support to data science. Here some understanding on “when-to-use-what”

•  R is very rich when you get into the descriptive statistics, Inference, statistical modeling and start plotting your data on the bar, pie chart and histogram. When your data is pretty much shaped and easily consumable for statistical modeling using vectors, matrix etc.
• First time learner who have some knowledge on statistics can start getting depth of Graph-cum-visualization with their data using R in terms of  trends, identify the correlation etc. I observed that you don’t need to start practicing R as a separate programming language. You can very well start sculling your boat in depth of statistics keeping R in another hand. 
•  R plays vital role for analyst who love to see the data distributions before drawing conclusion. It also helps analysts to visualize outliers and data density of given data set.
• As you start getting  more into probabilistic problems and probabilistic distribution R ease the data manipulation using vector and matrix. Even same applies to linear regression problems also.
• With support of R to stat rich problems you don’t need to get into the complexities of python, OOPS and understanding of the data types nitty-gritty.

Now, when you start getting into space of predictive modeling, machine learning and mathematical modeling, Python can give a easy hand. Mathematical functions, algorithmic problems find good support from Python libraries for k-means & hierarchical clustering, multivariate regression, SVM etc. Not limited to this, but it also has good support from data processing & data munging libraries like Pandas and NumPy. Here are some cents for python:

• We know! Python is full fledge “scripting language” and this statement tells everything. Most importantly, over the years Python has developed an eco-system for end-to-end analytics.
• Now you are not confined to data process and formalization, but you can easily play around data sourcing and data parsing too using programming model. This open the opportunities to analyze semi-structured data (JSON,XML) easily.
• With Python you have all liberties to start consuming the data from unstructured sources too. With streaming support from Hadoop extend the possibilities of using python on unstructured data stored on HDFS and from HBase for graph & networked data processing.
• With rich libraries like Scikit-learn you can do all text mining, vectorize the text data and identify similarities between posts and texts.
• Having OO language in your hand your program will be far structured and modular for all your complex mathematical calculation in comparison to R. I would rather call it as an easy to read.
• There are lot of ready-to-serve material in support of machine learning and predictive modeling using python. Read these two in combination: Machine learning with Python + Building ML with python. 

So in summary, we can bet on R when we start getting into statistical analysis and then eventually turn up towards Python to take your problem to a predictive end.

This write up doesn't meant to highlight R or Python's limitations. R has evolved as a good support to ML and does have combination with Hadoop as RADOOP. However, Python also has good support to statistics and does have rich library (matplotlib) for visualization. But, as i mentioned earlier in this write up, above finding points are solely based on ease of use while you learn Data Science. I suppose once matured we can develop expertise in any one on them as per job role.

Original post: http://datumengineering.wordpress.com/2014/02/08/r-python/