Sunday, August 11, 2013

Decision Trees

I just completed working through Chapter 7 of Programming Collective Intelligence (PCI). This chapter demonstrates how, when and who you should use the decision tree construct. The method described was the CART technique.

The basic summary is: A decision tree has each branch node represent a choice between a number of alternatives, and each leaf node represents a decision or (classification). This makes decision tree another supervised machine learning algorithm useful in classifying information.

The main problem it overcome in defining a decision tree is how to identify the best split of the data points. To find this you need to go through all the sets of data, and identify which will give you the best split (gain) and start from there.
For some more technical information about this split / gain:
http://en.wikipedia.org/wiki/Information_gain_in_decision_trees

The biggest advantages I see in using a decision tree are:
It's easy it is to interpret and visualise.
Data didn't need to be normalised or something between -1 and 1.

Decision trees however cant be effectively used on large datasets with a large number of results.

As with my previous Classifiers post, I ended up using SQLite in memory db as it's such a pleasure to use. I did venture into using LambdaJ, but it actually ended up being such an ugly line of code I left it and simply did it manually. I have not looked at the Java 8 implementation of lambdas yet, I just hope it doesn't end in code like (with a whole bunch of static imports):

falseList.add(filter(not(having(on(List.class).get(col).toString(), equalTo((String) value))), asList(rows)));

So my java implementation of the PCI decision tree ended up looking like (All code in Github) :

(once again ...  about 50% more code :) ).. really beginning to enjoy Python, I do see me using that for all future AI / ML type work as a first choice.


12 comments:

  1. This story is very important.

    ReplyDelete
  2. Amazing Article ! I would like to thank you for the efforts you had made for writing this awesome article. This article inspired me to read more. keep it up.
    Correlation vs Covariance
    Simple Linear Regression
    data science interview questions
    KNN Algorithm
    Logistic Regression explained

    ReplyDelete
  3. Through this post, I know that your good knowledge in playing with all the pieces was very helpful. I notify that this is the first place where I find issues I've been searching for. You have a clever yet attractive way of writing.
    data scientist training and placement in hyderabad

    ReplyDelete
  4. It is perfect time to make some plans for the future and it is time to be happy. I've read this post and if I could I desire to suggest you some interesting things or suggestions. Perhaps you could write next articles referring to this article. I want to read more things about it!
    data scientist training and placement

    ReplyDelete
  5. I am glad to discover this page. I have to thank you for the time I spent on this especially great reading !! I really liked each part and also bookmarked you for new information on your site.
    Data Science Course in Delhi

    ReplyDelete
  6. i am glad to discover this page : i have to thank you for the time i spent on this especially great reading !! i really liked each part and also bookmarked you for new information on your site.
    machine learning institute in delhi

    ReplyDelete
  7. Wonderful blog. I delighted in perusing your articles. This is genuinely an incredible perused for me. I have bookmarked it and I am anticipating perusing new articles. Keep doing awesome!.data analytics institute in delhi

    ReplyDelete
  8. Your website is really cool and this is a great inspiring article. cyber security course in delhi

    ReplyDelete
  9. If you are being attentive to learn several strategies then you ought to browse this article, I am certain you'll get much additional from this article. data scientist course in mysore

    ReplyDelete
  10. I want to leave a little comment to support and wish you the best of luck.we wish you the best of luck in all your blogging enedevors
    data science course in faridabad

    ReplyDelete
  11. I want to leave a little comment to support and wish you the best of luck.we wish you the best of luck in all your blogging enedevors
    data analytics course in faridabad

    ReplyDelete

Popular Posts

Followers