How to find important features in this problem I was just thinking how ML techniques can be applied in the retail industry. Suppose we have data from a retailer who deals with apparel and cloth in this format 
and for each item there are pre-defined features, for example a shirt will have features like color, half/full sleeves etc.. I want to understand how to extract important features of "most sold items" from this data. For example if I find that shirts are the most commonly sold item, then which kind of shirt : Black in color, Half Sleeves, etc...
I was thinking to use decision trees here. I am not sure if this is a good approach.
 A: Lasso seems like it would be good.  Lasso (Least Absolute Shrinkage and Selection Operator) is like OLS, but it penalizes the "length" of the final coefficients by including a "regularizer" term.  
The actual paper is Tibshirani (1996).
The Lasso package and demo in R is http://cran.r-project.org/web/packages/genlasso/vignettes/article.
The lasso is great because it penalizes a large number of coefficients to be exactly zero, and you can adjust the tuning parameter to see what drops out first and stays as you become more strict about learning relevant features. 
EDIT: 
But as the commenter said, be careful of what you are actually learn from a model.   Additionally, if you are a larger firm and begin to change your production...be aware of https://en.wikipedia.org/wiki/Campbell%27s_law
A: Just get the data, decide how you want to define feature groups (colours per shirt type, or shirt type seperately, colors seperately, etc' ) and encode thema s features using sci-kit learn.
http://scikit-learn.org/stable/modules/preprocessing.html#encoding-categorical-features
