let's say you have a big IRC chan log, and you want to find out what user is using multiple accounts. As input you have the time the user connects to the server, and some sort of text analysis ( word frequency, and so on), and as output you want the likelihood two user "matches".
Is it possible to do it using ANN? Are there better algorithms to accomplish that task?
PS : use IP addresses is not an accepted solution :)
The problem with using neural networks is that you need a robust set of training data--that is, you need to have lots of examples of people using multiple accounts where you already know that's what they're doing. Furthermore, if the people you're trying to identify have ever played a role-playing game, they'll probably be able to make themselves seem quite a bit different if they want to.
So, if people are acting just like themselves and you have a pretty good training data set, then you stand a chance. You should probably start with methods used by forensic linguistics.
But I suspect that what you'll probably end up doing is identifying people who are sort of similar to each other. Good for a matchmaking site, perhaps; not so cool for most other things. (For example, I would think this would be a perfectly dreadful way to try to find members of Anonymous in other guises.)
This problem is known as "authorship detection" (or sometimes, in a particular domain, "plagiarism detection"). It can be done using a variety of statistical algorithms, of which neural networks aren't the easiest.
Check out the Cavnar & Trenkle algorithm for text classification. That may be made into a useful baseline algorithm for this task. Implementations in various languages are available on the web. You may want to turn it into a clustering algorithm instead of a classifier.
Related
I'm writing up a Smart Home software for my bachelor's degree, that will only simulate the actual house, but I'm stuck at the NLP part of the project. The idea is to have the client listen to voice inputs (already done), transform it into text (done) and send it to the server, which does all the heavy lifting / decision making.
So all my inputs will be fairly short (like "please turn on the porch light"). Based on this, I want to take the decision on which object to act, and how to act. So I came up with a few things to do, in order to write up something somewhat efficient.
Get rid of unnecessary words (in the previous example "please" and "the" are words that don't change the meaning of what needs to be done; but if I say "turn off my lights", "my" does have a fairly important meaning).
Deal with synonyms ("turn on lights" should do the same as "enable lights" -- I know it's a stupid example). I'm guessing the only option is to have some kind of a dictionary (XML maybe), and just have a list of possible words for one particular object in the house.
Detecting the verb and subject. "turn on" is the verb, and "lights" is the subject. I need a good way to detect this.
General implementation. How are these things usually developed in terms of algorithms? I only managed to find one article about NLP in Smart Homes, which was very vague (and had bad English). Any links welcome.
I hope the question is unique enough (I've seen NLP questions on SO, none really helped), that it won't get closed.
If you don't have a lot of time to spend with the NLP problem, you may use the Wit API (http://wit.ai) which maps natural language sentences to JSON:
It's based on machine learning, so you need to provide examples of sentences + JSON output to configure it to your needs. It should be much more robust than grammar-based approaches, especially because the voice-to-speech engine might make mistakes that will break your grammar (but the machine learning module can still get the meaning of the sentence).
I am no way a pioneer in NLP(I love it though) but let me try my hand on this one. For your project I would suggest you to go through Stanford Parser
From your problem definition I guess you don't need anything other then verbs and nouns. SP generates POS(Part of speech tags) That you can use to prune the words that you don't require.
For this I can't think of any better option then what you have in mind right now.
For this again you can use grammatical dependency structure from SP and I am pretty much sure that it is good enough to tackle this problem.
This is where your research part lies. I guess you can find enough patterns using GD and POS tags to come up with an algorithm for your problem. I hardly doubt that any algorithm would be efficient enough to handle every set of input sentence(Structured+unstructured) but something that is more that 85% accurate should be good enough for you.
First, I would construct a list of all possible commands (not every possible way to say a command, just the actual function itself: "kitchen light on" and "turn on the light in the kitchen" are the same command) based on the actual functionality the smart house has available. I assume there is a discrete number of these in the order of no more than hundreds. Assign each some sort of identifier code.
Your job then becomes to map an input of:
a sentence of english text
location of speaker
time of day, day of week
any other input data
to an output of a confidence level (0.0 to 1.0) for each command.
The system will then execute the best match command if the confidence is over some tunable threshold (say over 0.70).
From here it becomes a machine learning application. There are a number of different approaches (and furthermore, approaches can be combined together by having them compete based on features of the input).
To start with I would work through the NLP book from Jurafsky/Manning from Stanford. It is a good survey of current NLP algorithms.
From there you will get some ideas about how the mapping can be machine learned. More importantly how natural language can be broken down into a mathematical structure for machine learning.
Once the text is semantically analyzed, the simplest ML algorithm to try first would be of the supervised ones. To generate training data have a normal GUI, speak your command, then press the corresponding command manually. This forms a single supervised training case. Make some large number of these. Set some aside for testing. It is also unskilled work so other people can help. You can then use these as your training set for your ML algorithm.
I want to cluster people into groups based on their interests. For eg. people who like machine learning and graphs may be placed in a group and people who have interest in mathematics and economics etc. may be placed in a different group.
The algorithm should be able to decide which people have most matching interests based on the interests of the people and create clusters.It should also be able to output about other persons in the group in which a particular person is placed.
This does not sound like a particularly difficult clustering problem, and any of the off-the-shelf clustering algorithm will probably work well. If you know how many clusters you want, then try k-means or k-medoid clustering. If you don't know how many clusters, then try agglomerative clustering.
The difficult part of the problem will be the features. You mentioned that 'interests' could be used as the features upon which to cluster, but feature engineering and selection will always involve some trial and error.
Without more context of your problem, I can't really give a definite answer. Most clustering algorithms will work though, the problem is how "good" are your results. I'm quoting the word "good" because you'll need some sort of metric to measure that (generally inter-cluster and intra-cluster distance).
Here's the advice given to me when I was taught on how to decide on an algorithm for data mining: Try the simplest algorithms first - quite often these are overlooked but perform quite well (Naive Bayes for supervised learning is a classic example).
To start you off, try something like K-means which is a simple and popular method, you can find more info here http://en.wikipedia.org/wiki/K-means_clustering (if you look at the Software section you can also find a list of implementations that you could try).
The second part of the criteria is to be able to output the other people in the group based on a target person. This is doable in all clustering algorithms since you'll have X subsets of people, you simply need to find the subset which the target person is in and then iterate that subset and print all the people within out.
I think the right approach will be Kmeans clustering. The most important part of your problem is feature selection.
Try with some features that you think are most important and simply apply kmeans in some statistical programing language like R, inspect the result and improve it by feature modification or selecting more appropriate features.
Hit and trial can give you insight if you are not sure about feature selection.
If you can provide some sample data, it will help to give some specific solutions to your problem.
Its coming a bit late, but there's actually an app in the windows store that is doing exactly that : finding profiles having similar characteristics
its called k-modo
Simple item-to-item recommendation systems are well-known and frequently implemented. An example is the Slope One algorithm. This is fine if the user hasn't rated many items yet, but once they have, I want to offer more finely-grained recommendations. Let's take a music recommendation system as an example, since they are quite popular. If a user is viewing a piece by Mozart, a suggestion for another Mozart piece or Beethoven might be given. But if the user has made many ratings on classical music, we might be able to make a correlation between the items and see that the user dislikes vocals or certain instruments. I'm assuming this would be a two-part process, first part is to find correlations between each users' ratings, the second would be to build the recommendation matrix from these extra data. So the question is, are they any open-source implementations or papers that can be used for each of these steps?
Taste may have something useful. It's moved to the Mahout project:
http://taste.sourceforge.net/
In general, the idea is that given a user's past preferences, you want to predict what they'll select next and recommend it. You build a machine-learning model in which the inputs are what a user has picked in the past and the attributes of each pick. The output is the item(s) they'll pick. You create training data by holding back some of their choices, and using their history to predict the data you held back.
Lots of different machine learning models you can use. Decision trees are common.
One answer is that any recommender system ought to have some of the properties you describe. Initially, recommendations aren't so good and are all over the place. As it learns tastes, the recommendations will come from the area the user likes.
But, the collaborative filtering process you describe is fundamentally not trying to solve the problem you are trying to solve. It is based on user ratings, and two songs aren't rated similarly because they are similar songs -- they're rated similarly just because similar people like them.
What you really need is to define your notion of song-song similarity. Is it based on how the song sounds? the composer? Because it sounds like the notion is not based on ratings, actually. That is 80% of the problem you are trying to solve.
I think the question you are really answering is, what items are most similar to a given item? Given your item similarity, that's an easier problem than recommendation.
Mahout can help with all of these things, except song-song similarity based on its audio -- or at least provide a start and framework for your solution.
There are two techniques that I can think of:
Train a feed-forward artificial neural net using Backpropagation or one of it's successors (e.g. Resilient Propagation).
Use version space learning. This starts with the most general and the most specific hypotheses about what the user likes and narrows them down when new examples are integrated. You can use a hierarchy of terms to describe concepts.
Common characteristics of these methods are:
You need a different function for
each user. This pretty much rules
out efficient database queries when
searching for recommendations.
The function can be updated on the fly
when the user votes for an item.
The dimensions along which you classify
the input data (e.g. has vocals, beats
per minute, musical scales,
whatever) are very critical to the
quality of the classification.
Please note that these suggestions come from university courses in knowledge based systems and artificial neural nets, not from practical experience.
Recently, I found several web site have something like : "Recommended for You", for example youtube, or facebook, the web site can study my using behavior, and recommend some content for me... ...I would like to know how they analysis this information? Is there any Algorithm to do so? Thank you.
Amazon and Netflix (among others) use a technique called Collaborative filtering to suggest things you might like based on the likes/dislikes of others who have made purchases and selections similar to yours.
Is there any Algorithm to do so?
Yes
Yes. One fairly common one is to look at things you've selected in the past, find other people who've made those selections, then find the other selections most common among those other people, and guess that you're likely to be interested in those as well.
Yup there are lots of algorithms. Things such as k-nearest neighbor: http://en.wikipedia.org/wiki/K-nearest_neighbor_algorithm.
Here is a pretty good book on the subject that covers making these sorts of systems along with others: http://www.amazon.com/gp/product/0596529325?ie=UTF8&tag=ianburriscom-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0596529325.
It's generally done by matching you with other users who have similar usage history / profile and then recommending other things that they've purhased/watched/whatever.
Searching for "recommendation algorithm" yields lots of papers. Most algorithms incorporate "machine learning" algorithms to determine groups of things (comedy movies, books on gardening, orchestral music, etc.). Your matching with those groups yields recommendations. Some companies use humans to classify things, too.
Such an algorithm is going to vary wildly from company to company. In many cases, it analyzes some combination of your search history, purchase history, physical location, and other factors. It probably will also compare purchases/searches amongst other people to find what those people have purchased/searched for, and recommend some of those products to you.
There are probably hundreds of these algorithms out there, but I doubt you can use any of them (that are actually good). Probably you are better off figuring it out yourself.
If you can categorize your contents (i.e. by tagging or content analysis), you can also categorize your users and their preferences.
For example: you have a video portal with 5 million videos .. 1 mio of them are tagged mostly red. If 80% of all videos watched by a user (who is defined by an IP, a persistent user account, ...) are tagged mostly red, you might want to recommend even more red videos to him. You might want to refine your recommendations by looking at his further actions: does he like your recommendations -- if so, why not give him even more, if not, try the second-best guess, maybe he's not looking for color, but for the background music ...
There's no absolute algorithm to do it, but all implementations will go into a similar direction. It's always basing on observing users, which scares me from time to time :-)
There's whole lot of algorithms tackling the issue: Wiki article. It's a Machine Learning domain problem. Computer's can be learned using two main techniques: classification and clustering. They require some datasets as input. If the dataset is informative (really holds some useful patterns) than those ML techniques can dig most of it.
Clustering could be best to use for this kind of problem. It's main usage is to find similarities among points in provided dataset. If the points are, e.g. your search history, they can be grouped together to form certain clusters. If Your search history closely relates to another, a hint can be given - picking links that are most similar to Your's.
The same comes with book recommendations - it's obvious what dataset they use: "Other people who bought this product also bought Product A, Product B,...". The key here is to match your profile to other's and use the most similar to recommend.
The computer retrieves information from the human brain with complex memory scan process, sorts it accordingly and outputs results based on what you have experienced in your life so far.
I want to implement a media recommendation engine. I saw a similar posts on this, but I think my requirements are bit different from those, so posting here.
Here is the deal.
I want to implement a recommendation engine for media players like VLC, which would be an engine that has to care for only single user. Like, it would be embedded in a media player on a PC which is typically used by single user. And it will start learning the likes and dislikes of the user and gradually learns what a user likes. Here it will not be able to find similar users for using their data for recommendation as its a single user system. So how to go about this?
Or you can consider it as a recommendation engine that has to be put in say iPods, which has to learn about a single user and recommend music/Movies from the collections it has.
I thought of start collecting the genre of music/movies (maybe even artist name) that user watches and recommend movies from the most watched Genre, but it look very crude, isn't it?
So is there any algorithms I can use or any resources I can refer up to?
Regards,
MicroKernel :)
What you're trying to do is quite challenging... particularly because it's still in the research stage and a lot of PHDs from reputable universities across the world are trying to get a good solution for that.
SO here are some things that you might need:
Data that you can analyze:
Lots, and lots, and lots of data!
It could be meta data about the media (name, duration, title, author, style, etc.)
Or you can try to do some crazy feature extraction from the media itself.
References to correlate the data to.
Since you can't get other users, you always need the user feedback.
If you don't want to annoy your user to death with feedback questions, then make your application connect to a central server so you can compare users.
An algorithm that can model your data sufficiently well.
If you have no experience at all, then try k-nearest neighbor (the simplest one).
Collaborative filtering
Pearson Correlation
Matrix Factorization/Decomposition
Singular value decomposition (SVD)
Ensemble learning <-- Allows you to combine multiple algorithms and take advantage of their strengths.
The winners of the NetFlix prize said this:
Predictive accuracy is substantially
improved when blending multiple
predictors. Our experience is that
most efforts should be concentrated in
deriving substantially different
approaches, rather than refining a
single technique. Consequently, our
solution is an ensemble of many
methods.
Conclusion:
There is no silver bullet for recommendation engines and it takes years of exploration to find a good combination of algorithms that produce sufficient results. :)