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Ask HN: What is the best way to learn Machine Learning in Python?

87 points by karan_dev ↗ HN
I am comfortable in coding, also familiar with python programming. What approach should i follow to learn machine learning with in SHORT TIME.

Should i start with a book(if yes which one), or with a machine learning library or with a project or with complete machine learning algorithm implementation in python.

Please provide me step by step guide which i should follow (with the source links and references[if possible]) to learn machine learning in one or two months.

49 comments

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drallison
Machine Learning is a sub-field of computer science and an area of intense current research. It has nothing to do with Python (a programming language) except that some machine learning algorithms might be implemented in Python.

You might find Andrew Ng's Stanford Coursera course a good place to start. https://www.coursera.org/learn/machine-learning/home/info.

cowpig
Well, you could certainly argue that python has the best machine learning libraries. So it's at worst a relevant programming language to the field.

edit: +1 to Andrew Ng's Coursera course though!

sfsylvester
Was there a reason Ng decided to teach the course in Octave rather than Python? The only time I've ever used .m files was during the course.

I appreciated the challenge of thinking from an array based language, but I felt it held me back from directly comparing my solutions to the tutorials to external sources. (Unless that even in of itself was the reason).

craigching
"Introdocution to Statistical Learning" by Trevor Hastie et al. [1] They have a free online class through Stanford [2] Sign in to their system and you can take the archived version for free.

ISL is an excellent, free book, introducing you to ML, you can go deeper, but, to me this is where I wish I'd started. I am taking the Data Science track at Coursera (on Practical Machine Learning now) and I am kicking myself that I didn't start with ISL instead.

Now, I know you specifically asked about Python, but the concepts are bigger than the implementation. All of these techniques are available in Python's ML stack, scikit-learn, NumPy, pandas, etc. I don't know of the equivalent of ISL for Python, but if you learn the concepts and you're a programmer of any worth, you will be able to move from R to Python. Maybe take/read ISL, but do the labs in Python, that might be a fun way to go.

Lastly, to go along with ISL, "Elements of Statistical Learning" also by Hastie et al is available for free to dive deeper [3]

[1] -- http://www-bcf.usc.edu/~gareth/ISL/

[2] -- https://lagunita.stanford.edu/courses/HumanitiesandScience/S...

[3] -- http://statweb.stanford.edu/~tibs/ElemStatLearn/

cschmidt
I also think this is one of the best entry level books, and the Stanford course looks good. This is what I recommend to people. In some ways, R is a very good match for this material, and you could move to python later.
loumf
I liked "Programming Collective Intelligence" http://www.amazon.com/Programming-Collective-Intelligence-Bu..., but it might be a little dated (in not using the latest libraries). It's a good way to learn some simple algorithms (optimization, clustering).

Also, rather than learning ML in 2 months (which is a very unfocussed and unattainable goal) -- try to narrow it down to some problem domain. You'd get better recommendations if you are more specific.

jawns
Step-by-step guide, with source links and references?

I don't think that's necessarily something one can (or ought to) expect to order up on Hacker News.

theseatoms
This. "Please provide ..." is pretty demanding. At least be courteous when asking for free labor.

That said, I'm also interested in the topic. As others are acknowledging, it's a broad field and one really needs to focus on well-defined projects in order to learn anything tangible.

jmount
I've seen the phrase "please provide" a lot. And I agree with you, I've never seen it actually used politely- it is always comes off like a strong demand. Maybe part of the problem is it is a stock phrase on exams.
chc
I suspect that a lot of them might not be native English speakers (e.g. OP's username suggests that he is from India, where a lot of people speak English, but it is relatively few people's native tongue).
karan_dev
Yes, I am from India, And it was my first question on Hacker News. Apologies if i offended you with my language, I should not have used those combination of words.
theseatoms
Hey, sorry about calling you out. My bad.
stonesam92
While it certainly comes off as demanding, I think it's important to remember that English is not necessary the OP's first language.

"Never attribute to malice that which is adequately explained by stupidity."

Note: "Stupidity" is obviously not the correct word for this situation, but the quote is still relevant.

edoceo
I replace Stupidity with Ignorance which, I think, is a solvable problem.
selleck
Peter Norvig's Artificial Intelligence:

http://www.amazon.com/Artificial-Intelligence-Modern-Approac...

Has plenty of examples in Python. You can also look at different Udacity courses. They have a couple dealing with ML with Python.

craigching
I have Norvig's book, I'm not sure I'd recommend that as an introduction ;) Awesome book though!
plinkplonk
AIMA is about as introductory as these texts get (and still be valuable). It in an undergrad textbook after all.
craigching
I guess my point is that it's such a broad overview of all topics that fall under artificial intelligence that you don't get much of a good introduction to applying machine learning. But point taken, you're right, it is an introductory text.
88e282102ae2e5b
I don't mean to be blunt, but I don't think you're going to get what you want out of machine learning if you still need people to give you step-by-step instructions.
bra-ket
that's how education works
jmount
No, it really is not.
solve
The people demanding you pay them tens of thousands per year, for them to tell you how to learn, say it is. We can trust them, right?
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babygoat
Do you really believe that's how higher education works?
solve
Do you not believe that's how mature businesses work?
6d0debc071
It's how some education works. But instruction has to be relevant to the skills and abilities of those receiving it, and has to address those things on which they have a deficit of understanding. If your approach to education is simply to stand at the front of the room and read a book to them, then you're not a very good educator.

It's a bit more complex than simply: give someone step-by-step instructions and they have the skill and/or knowledge. If they're still at the level where you have to explain everything, then that's a fairly low level of skill - and it's not clear that instruction on all subjects is appropriate to that level of skill... just as you wouldn't go up to an aeronautics engineer, ask for a step by step instruction guide on how to build a 747, and then call yourself an aeronautics engineer.

You might, if you had a very good memory, be able to build a 747 (waving aside the logistical difficulties of doing so) but you wouldn't understand why it worked, and you wouldn't know how to build any other aircraft. And if, instead, you asked her for a step-by-step guide on how to learn what she knew in a couple of months... Well, the answer would likely be that she knew a lot more than could be communicated in two months, and that you needed a higher level of understanding of physics and so on to ask a more refined question to which she would be able to give some sort of meaningful answer.

88e282102ae2e5b
OP clearly has not even googled this. "python machine learning" pulls up many easily-accessible articles meant for beginners with no background in machine learning. The scikit-learn website is chock full of tutorials meant for beginners, with code examples!

How is someone with this little motivation going to learn something so complex? I want to allocate my time helping people who at least try first.

icpmacdo
I dont think hacker news is a bad place to ask a question like this. The most helpful of the answers on a popular post are going to eliminate a lot of low quality content that your going to come across with Google.
scuba_man_spiff
I enjoyed this book you may want to check out.

http://www.amazon.com/Machine-Learning-Python-Techniques-Pre...

The main thing to understand though is that machine learning is a big topic, and you aren't going to be able to become an expert in two months.

Narrow down to a specific area, or type of problem, and focus on learning techniques and tools for that.

My guess is that there's something your working on or want to work on which is why want to learn. If that's the case, I'd recommend that read up a bit to give yourself a good understanding of the different kinds of problems out there (classification, prediction, anomaly detection, etc...), and different classes of tools available, and then pick a simple real world problem to try to tackle that is similar.

The best way to really learn is going to be getting hands on with a project and suffering through after you've read up a bit to understand the basics. Then when you hit something can't wrap your head around, search and read articles (or talk to someone with experience and expertise) until it clicks and you can proceed on working through.

By the end you'll have a good grasp of at least one technique, and be in a great place to keep learning more.

chipmonkey75
My personal preference is to learn by doing, and the best place I've found for this particular task is Kaggle (http://www.kaggle.com). They have a variety of datasets and scored data mining tasks, great forums for every level, code examples, and even a set of tutorials specifically for learning scikit (one of Python's machine learning libraries): http://blog.kaggle.com/2015/04/08/new-video-series-introduct...

I don't have any relationship with Kaggle other than being a semi-active user, but I really dig what they've got going. For a step-by-step approach, start with their blog posts and work on their "Getting Started" competitions. Everything you need is there.

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apeeyush
I created a github repo (https://github.com/apeeyush/machine-learning) to store and organize the codes I used in Kaggle contests (mainly knowledge contests). Recently, I have participated in some vision and CTR prediction contests as well but could not update them here since the code is still very hacky. Will really appreciate any contribution from the community.
craigching
That's a nice repository, thanks for sharing! I'll be combing through that as I make the transition from R to Python ;)
rapid_snail
Machine learning is a very large field - you shouldn't expect to learn it in one or two months. Maybe you will be able to scratch the surface and learn to implement a few learning algorithms.

I would recommend starting with scikit-learn.

jmount
Which do you want to know? (as it affects the answer greatly). And how short is "SHORT TIME"? For certain small values of "SHORT TIME" the answer is come back when you have more time.

How to apply machine learning using Python? (then scikit learn related materials).

How to tinker with machine learning implementations? (then which one are you trying to tinker with and what problem that isn't solved in the standard libraries is your concern?)

The theory of machine learning? (then "The Elements of Statistical Learning" and "An Introduction to Statistical Learning", but that is in R not in Python)

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burningion
I just started going down this path. I began with using audio analysis to do some machine learning. (Detecting a specific audio pattern very easily recognizable to humans). Can't get too specific about it, as it's under NDA. But I had a little under two weeks to get a prototype built that either proved or disproved it would be possible.

The very first thing I did was take a step back and understand the domain of the data I was working with, and what the best way to present it for machine learning would be. In my case, I had to understand what the best format for presenting my audio would be (slightly modified MFCCs), and what the best library would be to get my data in that format.

Next, I needed to build a data set of proper training data. This mean I had to manually build a (largish) data set that matched exactly what I was looking for. So I went and downloaded a bunch of example audio, and then manually went through it, tagging it into the two bins I was looking to differentiate against.

Once I had this, (which actually took much more time than the learning itself), I was ready to do the actual machine learning itself. I used Theano, and figuring out how to translate my dataset into a format digestible by Theano took another chunk of time. Once I had my data in the proper format for Theano, it came down to basically playing with how I presented my initial data to Theano, and then tweaking my gradient.

Finally, I was able to train and get a net that was about 80% right with my hypothesis. There were a few edge cases I hadn't anticipated that wouldn't necessarily work well, but it gave us enough confidence to go through with more machine learning for our project.

So, takeaway suggestions: find a real project, something you want to learn, and then just do it. Gather knowledge of your data, build a dataset, and test a hypothesis. Most of this isn't machine learning, it's mostly just moving and shaping data, and knowing what in your data is significant. The machine learning algorithms are really just a tiny piece of the whole picture. Good luck.

pjungwir
Machine learning is a pretty big field. The Coursera course is very good. It uses Octave not Python, but what you learn will be easy to transfer. It is mostly focused on neural networks. If you don't already know linear algebra you should probably learn that first.

These are three very good O'Reilly books that all use Python:

- Programming Collective Intelligence: A broad and shallow survey of automated machine learning techniques.

- Data Analysis with Open Source Tools: Also a survey. More focused on manual data exploration.

- Python for Data Analysis: A pandas tutorial (and more). Very helpful to learn the ML tools in the python ecosystem.

Fitting all that into two months sounds challenging.

sozerberk
[1] -- First, you need to learn machine learning(ML) basics. Andrew Ng's course on Coursera is a good start: https://www.coursera.org/learn/machine-learning/home/info

It doesn't teach you ML with Python but it is extremely important to learn the ML concept without any programming language in mind. In addition to that course, any Google search will help you a lot. There are a lot of good explanations of ML concepts on various websites. If you don't understand how algorithms work, you will end up with copying and pasting example codes without knowing what you're doing. You need to imagine what you want to do in your head before you type any letter.

[2] -- Once you have the initial introduction, you can use Python to implement ML concepts. Fortunately, Python has a very easy to learn ML package: Scikit-learn (http://scikit-learn.org). It's free and is used by various companies such as Spotify and Evernote. Scikit-learn has a great documentation and many examples that will make the whole learning process exciting.

[3] -- After you feel comfortable with ML in Python, if you don't have datasets of your own, you can find a lot of datasets on UC Irvine's machine learning repository: http://archive.ics.uci.edu/ml/

The more you practice, the more comfortable you feel with playing with data. To cover a ML technique very well, play with every single parameter of the scikit-learn functions of that technique by using the same dataset. Also, always try to include visualization of the data (scikit-learn has examples with matplotlib to learn from how to do it) so you can actually see the changes of the implementation when parameters of the function change. This will make everything a lot easier.

Good luck!

bit2mask
Coursera Machine Learning is one of the best places to start, but there are countless resources. There's a huge, wonderful open list of links at Github[1]. I definitely recommend you take a look at it

There are also another great resources online, like those I list below:

1.) In-depth introduction to machine learning in 15 hours of expert videos[2]

2.) Deep Learning Tutorial (@ ufldl.Stanford.edu/tutorial/, can't post the link because I'm out of mana, I mean, not enough reputation yet)

[1]: https://github.com/josephmisiti/awesome-machine-learning

[2]: https://www.dataschool.io/15-hours-of-expert-machine-learnin...